United States Department of Agriculture
Agriculture Information Bulletin 410
296
This is a reprint of Part 4 from the 1977 Yearbook of Agriculture, Gardening for Food and Fun.
The Yearbook may be purchased at government bookstores or ordered from the Superintendent
of Documents, U.S. Government Printing Office, Washington, D.C. 20402. Original page
numbers from the entire book are used in this reprint.
The telephone rings in a county
Extension office. A harried voice
says, “My garden is growing more
than my family can eat, what shall I
do with it? How can I keep it from
spoiling?”
How many times during the gardening
season is this scenario repeated
in an Extension office? Too often to
count! The answers to these questions
are readily available in the
many bulletins, folders, and leaflets
on food preservation available from
county, State, and Federal Extension
agencies. The publications tell how
to preserve food safely and wholesomely,
but do little else to explain
why directions must be followed precisely.
Let’s take a look at the whys.
To understand food preservation,
first consider the sources. Home garden
food comes from plants: sources
of raw food are living, biological entities,
continuing to metabolize after
they are harvested. Plants also provide
a source of food for micro-organisms
which can grow on or in
them, spoiling food before it can be
eaten. The primary objective of food
preservation is to prevent food spoilage
by preserving food until it can be
used by people.
Historically, food preservation and
processing assured a food supply and
prevented starvation. This is probably
the major reason why food is
processed today in many developing
countries. In the United States, however,
affluence and a plentiful food
supply now influence the reasons for
food preservation. Today, Americans
live many miles from rural areas
where food is produced. Consequently,
food must be preserved to assure
the nonfarm population an adequate
supply.
Our people want a food supply that
is safe, high in quality and appearance,
adequate nutritionally, and reasonably
priced. Many consumers try
to obtain these food attributes by
returning to the “old ways” of growing
and preserving food themselves.
To understand food preservation,
let’s look at five causes of food
spoilage or deterioration (four are
biological, the fifth physical or mechanical):
(1) The primary cause of food
spoilage in the United States is microbiological.
Micro-organisms are small
living organisms such as yeast, molds,
or bacteria. They are the chief causes
of microbial spoilage.
Related to microbiological spoilage
of food and also a concern in food
preservation is microbiological food-borne
disease. There are two types.
Salmonellosis is an example of a food
infection where food may not support
growth of the micro-organisms but
merely serves to transfer it from the
source to the human host. In the
second type, the micro-organism
grows in the food and produces a
poison or toxin which when eaten,
causes illness symptoms. Staphylococcal
food poisoning is the most common
of the second type in the US.
Severity of the major types of food-borne
disease in the United States
varies from the finality of botulism
to the mild discomforts of Clostridium
perfringens food poisoning. Food preservation
techniques, followed precisely,
prevent food-borne disease.
(2) The second cause of food spoilage
is vermin such as rodents, rats,
mice and insects that attack the food
and eat or contaminate it before humans
can use it. These vermin ruin
millions of pounds of food each year.
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WHAT ELSE CAN WE DO WITH TOMATOES?!!
(3) Have you noticed how an apple,
left at room temperature, eventually
gets soft, wrinkles, and dries out?
This spoilage is called senescence:
an aging process caused by continued
respiration of the apple, eventually
making it useless as food. Other
foods also spoil this way.
(4) Related to senescence is chemical
deterioration of food. The development
of rancid flavor in high
fat-containing foods is a chemical reaction
which brings about an undesirable
change. Loss of color or
bleaching and loss of vitamins, while
food is stored, are chemical deteriorations
that can be controlled with
proper preservation methods.
Both senescence and chemical deterioration
are conveyed by organic
compounds called enzymes. These
enzymes are produced by all living
organisms and their function is to
speed up or cause the metabolic reaction
necessary for the organism’s
continued existence. The enzymes
will continue to act after the plant is
harvested, and bring about deterioration
of the food unless controlled or
destroyed. Preservation methods
have been developed to control or destroy
these organic catalysts.
(5) The last cause of food spoilage
concerns food handling. Physical or
mechanical damage to the food causes
bruising, crushing, cutting, and wilting
or water loss. These mechanical
defects, besides detracting from the
food’s appearance, allow easier entry
of micro-organisms, insects, and other
vermin to cause spoilage and aging.
Food preservation processes have
been developed to slow down, prevent,
or stop completely these processes
of food spoilage.
An inherent part of food preservation
is the package containing the
food before or after processing.
Packaging provides a convenient
method of handling food, prevents
contamination during and after processing,
bars vermin infestation, supplies
a container for storage, and is a
necessary part of preservation. An
example would be a mason jar with
proper seal for pickling.
What are the major methods available
for home preservation of food?
How are they carried out? Why do
they prevent spoilage, food-borne disease,
and give desired attributes of
safety, quality, appearance, nutrition,
and economy? The economics of food
preservation will be developed in a
subsequent chapter. Let’s explore the
following available methods for home
preservation of food:
Control of temperature of the food, heat or cool
Control of the food’s acid content
Control of moisture content of the food
The major method used for home
preservation of food is temperature
control. This includes canning with
a pressure canner or a boiling water
bath, blanching food before freezing,
refrigerating food, and freezing it.
Micro-organisms which cause disease
and food spoilage are sensitive to environment
temperature variations. By
increasing the food’s temperature,
micro-organisms are destroyed. When
the temperature is decreased, their
growth is inhibited.
Let’s look at the temperature scale
300
illustration and see how temperature
affects micro-organisms. To prevent
growth of micro-organisms in food
and subsequent microbial spoilage,
food must be kept out of the temperature
range that allows growth.
This is most commonly achieved by
refrigerating or freezing. Refrigeration
slows down or stops microbial spoilage.
Freezing stops it completely.
EFFECT OF TEMPERATURE ON MICRO-ORGANISMS
Degrees Fahrenheit
225
spore-forming bacteria killed
220-250
proper canning temperatures (low acid foods)
212
water boils; pressure canner needed to obtain temperatures above boiling
170-210
non-spore-forming bacteria, yeasts, and molds killed
120-140
some bacteria can grow
98.6
body temperature
70-80
room temperatures may fall in this range
60-120
DANGER ZONE most bacteria, including food-poisoning types, grow rapidly over this temperature range
32
water freezes
30-60
cold-tolerant bacteria, yeasts and molds grow
0
no microbial growth
Enzymatic activity, while slowed
down by freezing, is not stopped in
many vegetables and these enzymes
must be destroyed by blanching the
vegetables before freezing to prevent
enzymatic deterioration. Successful
preservation by freezing must deactivate
any enzymes that might be in
the food as well as rapidly lower the
food temperature to below freezing
to stop microbial activity.
Freezer burn, a common problem
with frozen foods, comes from improper
packaging. Food moisture is
lost in freezer burn, which results in
undesirable flavor and texture
changes. Freezer burn can be controlled
by proper packaging, proper
storing temperature, and avoiding
long-term storage.
Refrigeration or storage above
freezing, but below room temperature,
preserves food for days and
sometimes weeks. Refrigerated storage
slows down activities of enzymes
in the food and reduces metabolism
of the contaminating micro-organisms.
Preservation of food by reduced
temperature, refrigeration, or freezing
is achieved because enzyme activity
and microbial deterioration are
slowed down or stopped.
Increasing the temperature of food
to achieve preservation also results
in destruction of the micro-organisms
that produce spoilage and disease.
Time and temperature regulate this
preservation. Theoretically, since
food will be stored at temperatures
which will allow most microbes to
grow, the ideal heat treatment needed
to preserve the food would be one
that completely sterilizes the food,
that is, kills all attendant micro-organisms.
To achieve complete sterilization,
for example, every particle
of food in a jar must reach the required
temperature and be held there
long enough to destroy all micro-organisms.
The time required for heat to penetrate
to the center of the food in a
container (the slowest heating point)
is extremely important. Heat is transferred
through food in containers by
two mechanisms: conduction and convection.
The mechanism involved depends
on the consistency and amount
of liquid in the food. The heat penetration
rate is also influenced by size
of the container, type of heating
medium (wet steam vs. dry air), ratio
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of solid to liquid, kind and size of
solid material in container, amount of
fat, and amount of salt and sugar.
For example, pumpkin or squash
can be home canned in two forms:
strained or cubed. University of Minnesota
research has shown that the
time required for the center of a pint
jar of strained squash (which heats
by conduction) to reach sterilization
temperature is three to four times
as long as for a pint jar of cubed
squash (which heats by convection).
The same is true of creamed corn
(heats by conduction) and whole kernel
corn (heats by convection).
Methods and recipes recommended
by Extension agencies take into account
all of these factors and must be
followed precisely to assure a safe
and wholesome product.
Why is it necessary to heat-process
pint jars of string beans at 240° F for
20 minutes in a pressure canner when
tomatoes can be successfully heat-processed
in a boiling water bath?
This brings up the second method of
preserving food at home, controlling
the food’s acid content. This method
is most commonly used in combination
with heat processing.
Most foods contain naturally occurring
organic acids. Some foods
contain more of these acids and are
called acid or high acid foods. These
organic acids have the ability to
limit, inhibit, or prevent the growth
of many of the micro-organisms producing
spoilage and disease. The degree
of inhibition is related to the
amount of acid present.
A method used for measuring acid
content is called pH. A measure of
pH is a determination of the hydrogen
ion concentration which reflects
the amount of acid or alkali present
in the system. A scale from 0 to 14
is used. A pH of 7 is considered neutral,
above 7 alkaline, below 7 acidic.
Very few foods have a pH above 7.
The classification of foods in the
acid range below 7 is extremely important.
Above pH 4.6 most of the
spoilage type micro-organisms can
grow, as well as the dreaded Clostridium
botulinum (see discussion following
on botulism). In foods with a
pH greater than 4.6, it is necessary to
heat-process the food at temperatures
above boiling to obtain the desired
level of sterility.
There are some types of bacteria
that produce entities called endospores
or spores which are extremely
resistant to environmental stresses.
They are a means of assuring survival
in bacteria, although not themselves
a reproductive mechanism.
One growing or vegetative cell will
produce one spore, which under
proper growth conditions will germinate
and produce one cell. This one
cell continues to grow and can produce
millions of bacterial cells. Destruction
of the resistant spore necessitates
the use of temperatures above
that of boiling water (212° F).
BOTULISM. One of the most notorious
of the spore-forming bacteria is
Clostridium botulinum. When growing
in food this bacteria can produce
a deadly poison which causes botulism,
a deadly illness. The mortality
rate is 56 percent. This bacteria and
its spore are present in soil throughout
the world and as a result contaminates
most of the food we eat. But
the spore only germinates and grows
where there is suitable food, no air,
and a pH above 4.6. These conditions
exist in canned low acid foods.
To assure botulism-free home-canned
foods, it is absolutely essential
that low-acid foods be canned in
a pressure canner at temperatures
above 212° F. The poison produced
by this bacteria is one of the most
potent poisons known to humans. It
has been estimated that 1 cup (8
ounces) is sufficient to kill all the
humans on earth. It is not something
to take chances about. All home canning
procedures recommended by
Federal and State Extension agencies
302
are adequate to destroy this dreaded
spore-forming bacteria.
pH VALUE OF VARIOUS FOODS
High Acid
2.9
plums
3.0
gooseberries
3.2
dill pickles, apricots
3.3
apples, blackberries
3.4
sour cherries, peaches
3.5
kraut, raspberries
3.7
blueberries
3.8
sweet cherries
3.9
pears
4.3
tomatoes
4.6
————
Low Acid
4.8
okra
5.0
pumpkins, carrots
5.1
turnips
5.2
beets, string beans
5.4
sweet potatoes
5.5
spinach, asparagus
5.6
baked beans
5.7
red kidney beans
5.9
lima beans
6.0
succotash
6.2
peas
6.3
corn
7.0
hominy, ripe olives
Commercial canneries, which are
regulated by the Food and Drug Administration,
use similar processes to
assure safe canned foods. In the past
50 years, 75 percent of the reported
cases of botulism in the United States
have been caused by home-canned
food while less than 10 percent have
been caused by commercially canned
food. If proper home-canning procedures
are followed, botulism from
this source could virtually be eliminated
as a cause of death in the US.
On the lower side of pH 4.6, acid
content of the food will prevent
growth of Clostridium botulinum and
most of the other spore-forming bacteria.
Thus, these foods can be
preserved by using a lower heat
treatment. The most common types
of spoilage micro-organisms associated
with acid foods are yeasts and
molds. These organisms are acid-tolerant
and can grow in an acid environment.
They are killed at a lower
temperature than spore-forming bacteria.
Acid foods only need a heat
treatment in a boiling water bath for
a specified time to destroy the microbes
present.
Preservation of food by controlling
the acid content can be achieved in
two ways. One is to naturally ferment
the food—turning cabbage into
sauerkraut. The other is to add an
organic acid to the food to reduce the
pH—adding vinegar to cucumbers
to make pickles. Some foods such as
berries and fruits naturally contain
enough organic acids so their pH is
below 4.6, and preservation of these
foods requires only a boiling water
bath heat treatment or freezing.
In a natural fermentation, lactic
acid bacteria convert fermentable carbohydrates
in the food to lactic acid.
In this way the pH is reduced and
most bacterial growth inhibited.
When cabbage is fermented to sauerkraut,
the cabbage’s pH is reduced
from pH 6.8 during the fermentation
to less than 3.5. Cucumbers can also
be fermented to pickles by a similar
process; however, most pickles are
made by direct acidification of the
cucumbers.
Direct acidification, that is, adding
vinegar which contains 4 to 5 percent
acetic acid, is the most common
method of making cucumber pickles
in the United States. It is easier,
quicker, and foolproof. Often the natural
fermentation will go astray.
Other undesirable microbes may
grow, bringing unwanted changes in
the food: spoiling rather than preserving.
Other foods made by fermentation
include wine.
Regardless of the method used to
control the pH of food, to successfully
preserve food by this method it
is absolutely essential to heat-process
or freeze to prevent spoilage by yeasts
and molds. An example of spoilage in
cucumber pickles not heat-treated
after acidification is the development
of cloudiness and bubbling. This
303
common spoilage is caused by microbes
that would be destroyed by
heat processing.
Control of the moisture content of
food is one of the oldest preservation
methods. Removal of water from the
food prevents growth of most microbes
and slows down enzymatic
deterioration.
Water removal from food can have
several forms. The oldest and most
primitive method for removing water
is sun drying, which requires long
hot days with low humidity to dry
food evenly and quickly. Over-drying
and uneven drying will result in nutrient
destruction, microbial growth,
and other undesirable changes. Drying
of food in the home can be done
and a later chapter tells how.
Water activity or availability of
water in foods can also be controlled
by adding compounds to the food
which tie up the water chemically,
making it unavailable for use in an
enzymatic reaction or for use by the
micro-organisms. The two most common
home ingredients used in this
way are sugar and salt. In making
fruit preserves, the high sugar content
ties up the water and helps prevent
growth of many micro-organisms.
Methods used for preserving food
in the home are combinations of the
basic techniques discussed here.
Make certain the recipe you follow is
from a reliable source. Follow it precisely
and be assured of a safe and
wholesome food supply.
304
How to Minimize Quality Losses — Handling Raw Foods — Canning — Headspace — Freezing — Drying — For Further Reading:
All methods of preserving food will
alter, if not lower, the quality of
fresh fruits and vegetables, but these
changes can be minimized. For practical
understanding of how to minimize
quality changes you need to
know something about: (1) natural
differences in raw food, (2) natural
causes of quality deterioration, and
(3) how various food handling, preparation,
packaging and storage techniques
and conditions affect quality
retention.
Because of insufficient research information
on home preserved foods,
some research findings of commercially
processed food have been used
to foster an increased awareness of
factors affecting the quality of home
preserved food.
Natural differences in quality and
nutrient content in raw food often
exceed losses caused by preserving
food. Extreme variations (tenfold or
more) in vitamin A and C content
have been found in some fruits and
vegetables. These natural differences
are known to be caused singly or
collectively by differences between
varieties, climate changes between
seasons in the same region, and between
regions in the same year. They
are also influenced by some cultural
practices, and maturity of crops at
harvest.
Because of color, texture and especially
flavor qualities, some varieties
are more suited for canning;
others are more suitable for freezing.
Few varieties possess the all-purpose
criteria needed to preserve
them as either high-quality canned or
frozen products.
There is no single, ideal maturity
for harvesting or preserving fruits
and vegetables. Obviously, the quality
of canned or frozen products
made from any maturity other than
ideal for that specific commodity
lacks the ultimate potential of satisfaction
for eating.
Three natural causes account for
most quality changes in freshly harvested
fruits and vegetables—respiration,
enzymes and oxygen. Their
effects generally increase with the
time between harvest and preservation,
and at higher temperatures.
Freshly harvested fruits and vegetables
are living organisms. They are
sustained by cellular reactions known
as “respiration,” in which native enzymes
use oxygen and components
in food and give off heat, water and
carbon dioxide. The energy needed
to sustain respiration is obtained
from a storehouse of natural components
in food. As a result, natural
flavors and vitamins are diminished,
sugars and sometimes acids decrease,
and texture may soften. The speed
of respiration and the onset of its
effects differs among various fruits
and vegetables, and is generally lowered
by refrigerator temperatures.
Besides enzymes relating to respiration,
fruits and vegetables sometimes
contain other cellular enzymes
associated with reducing food quality.
These enzymes act with oxygen
to cause rapid discoloration of
bruised, peeled and sliced tissue; oxidation
of flavors, and excessive
softening.
The roles of oxygen in respiration
and other enzyme reactions have been
noted. Oxygen may react still another
way to lower food quality: autoxidation,
where sensitive flavor, color and
vitamin components are altered by
oxygen. This causes fading of colors,
off-flavors and, reduced vitamin retention.
305
These reactions occur quickly
during canning and drying of
foods, and also account for slow
changes during storage of preserved
food.
Because of the effects of respiration,
other enzymes, autoxidation,
and desiccation (loss of water), the
raw product temperature and the
time between harvest and preservation
are of utmost importance to preserving
high-quality fruits and
vegetables.
Ideal handling conditions vary with
the product. Small berry and stone
fruits, asparagus, green beans, beets,
broccoli, corn and leafy greens, to
name a few, should be preserved the
same day of harvest, for highest quality.
Apples, peaches, pears, plums
and tomatoes, if harvested at firm
maturity, should be ripened a few
days before preserving them. Other
fruits and vegetables may be stored
from a week to months before preservation
without significantly lowering
their quality.
From a nutritional standpoint, if
after harvest the handling and preservation
of these crops are carefully
planned and implemented, quality of
the preserved products can be equal
to food prepared from fresh market
fruits and vegetables.
Fruits and vegetables are recognized
as significant sources of vitamins
A, the B family, C, minerals,
and fiber.
Vitamin A, pro-carotene, is
heat-stable and insoluble in water
but is subject to a minor loss caused
by autoxidation. Therefore, losses
in home preserved foods are
insignificant.
Of the water-soluble vitamins, ascorbic
acid (C) and thiamin (B₁) are
subject to serious loss upon heating
foods. Riboflavin (B₂) is subject to
loss when raw or preserved foods
are exposed to light.
Removing the skins from peaches before canning.
Significant losses of water-soluble
vitamins and minerals occur when
food contacts water, such as in washing,
blanching, cooking or canning
foods. As would be expected, losses
due to leaching of water-soluble vitamins
and minerals rise with increased
cut or exposed food surface
areas, repeated exposures to water,
and more time in water, especially
when heated.
The effects on fiber in preserved
food is much the same as in fresh
cooked foods.
Home canned foods should have a
bright color, characteristic texture,
pleasant flavor and contain nutrients
naturally present. When all steps of
scientifically based canning directions
are carefully followed, color,
texture and flavor will be optimum.
These observable signs of quality are
also an index to nutrient retention of
that canned food.
Proper pretreatment of the fruit or
vegetable being canned is essential
for top quality. This includes using
only good, wholesome food at peak
eating quality. Any trace of moldy or
otherwise spoiled food should be
completely removed. All food must
be washed thoroughly.
306
Removal of skins from thin-skinned
foods such as tomatoes and peaches
is important. A short blanching time
in boiling water loosens the skins,
and a short cooling time in cold or ice
water stops the cooking of the food.
Because water leaches out vitamins,
dilutes color and flavor, and results
in a mushy product, do not allow
foods to soak unnecessarily in either
hot or cold water.
Air is an enemy of light-colored
foods, and should be kept from the
peeled or cut food. This can be done
with a commercial antioxidant (ascorbic
acid), lemon juice, or a simple
solution of two tablespoons each of
vinegar and salt per gallon of water.
Peel or cut food directly into such a
solution for maximum protection
from air. When enough food for a
canner load is prepared, drain and
rinse the food for best flavor.
The packing method used is one of
the most important factors in quality
canned products. Foods that are
heated before being put in jars have
better quality than foods packed raw
in jars. Heating destroys enzymes and
removes much of the air from food
tissues.
Enzymes must be destroyed quickly
for top-quality food. Removal of air
not only shrinks the food, but leads
to better color, flavor and nutrient retention,
and too, fruits are less likely
to float. Hot packed jars also have
higher vacuums, thus less oxidation
can take place.
Tomatoes and tomato juice are less
likely to separate if tomatoes are cut
and heated at once. Cutting activates
enzymes in tomatoes which then
change the pectins in the tomatoes
and causes separation. Heating right
after cutting inactivates the enzymes
and minimizes separation.
Sugar, salt and vinegar play important
roles in quality canned foods.
While sugar is not needed to safely
can fruits, it contributes to better
color, flavor and texture. Likewise,
vegetables may be safely canned
without salt, but when salt is used,
better flavor results. Salt is essential
for slow process pickles; vinegar is
needed for quick process pickles.
Canning or pickling salt should always
be used. Iodized salt will inhibit
proper fermentation and react with
the starch in some foods, causing
them to turn pink or blue.
Sugar concentration in sirups is
important to appearance of the fruit.
With a light sirup, fruits are less
likely to float than with a heavier
sirup. And with a light sirup, fewer
calories are added. Then too, the
cost is less than with a medium or
heavy sirup.
Using the proper amount of headspace
pays off in quality products.
Adequate headspace is needed so
food has enough room for expansion
during heat sterilization.
Generally, more headspace is
needed for foods heat-sterilized in a
pressure canner than those in a boiling
water canner, because of increased
expansion of foods at the
higher temperature.
With too little headspace, liquid is
more likely to cook out of the jars
during heat sterilization. This increases
the danger of seal failure due
to food particles that may be trapped
at the interface of the sealing surface.
With too much headspace, air remaining
in the jar can cause darkening of
the food, oxidized flavor, and lower
vitamin retention, especially in food
at the top of the jar.
Pressure canning low-acid foods is
receiving increased emphasis today,
mainly based on the greater safety of
this technique. The method also
offers an additional advantage that
is little known to home canners—improved
quality and nutrient
retention.
Generally an 18° F (10° C) rise in
canner temperatures increases the
307
destruction of bacteria tenfold. At
the same time, chemical changes
that affect color, flavor, texture and
nutrients of the food are only
doubled.
This means that for every 18° F
(10° C) increase in canning temperature,
bacteria are destroyed five
times faster than are vitamins, flavor,
color and texture. Accordingly, in
contrast to boiling water canning,
heat sterilizing in a pressure canner
at 240° F (116° C) (10 p.s.i.) destroys
bacteria about 17 times faster than
chemical changes are effected, accounting
for better nutrient and quality
retention of pressure canned low-acid
foods.
Be cautious about interpreting this
as an advantage in pressure sterilizing
acid foods. This technique can increase
quality and nutrient losses because
of the total time the jars of
food will be near or above boiling
water temperature.
For example, with tomatoes it takes
about 5 minutes until steam begins to
escape, 10 minutes to exhaust the air,
about 5 minutes to build up pressure,
5 minutes for heat sterilizing at 240° F
(116° C) and 30 to 45 minutes cooling
before opening the canner. That
adds up to about 55 to 80 minutes at
temperatures near or above 212° F
(100° C), as compared to the recommended
35 minutes for heat sterilizing
in a boiling water canner. Assuming
the average product temperature
is elevated above 212° F (100° C)
about half of this total time, the loss
in quality could be at least doubled.
Properly managed heat sterilization
has a great deal to do with the
quality of canned food. If the temperature
is too high or the time of
sterilization too long, the result is a
product with poor color, soft texture,
and less flavor. Tomatoes canned in
the pressure canner are an example.
After heat sterilization, a quality
canned food will have liquid covering
the solid food in the jar. The lid
must allow air, but not liquid, to escape
during heat sterilization. A low
liquid level in the jar may indicate the
lid did not function properly, pressure
was allowed to fluctuate in the
pressure canner, or the canner wasn’t
cooled completely before opening, or
raw pack was used. Foods not covered
with liquid will have poorer
quality.
Jars must be air-cooled naturally
after heat sterilization to maintain
quality as well as for safety. Delayed
cooling in tightly enclosed areas, such
as cardboard cartons, will decrease
quality of the product.
Storage conditions are vital to quality
of canned foods. If stored in a
light, rather than a dark place, light-sensitive
colors will darken gradually.
Some colors, such as carotenoids
in tomatoes and carrots will
gradually fade with prolonged storage.
Storage temperatures between 40
to 50° F (4.5° to 10° C), if the spot
is dry, are best for quality retention.
Quality losses are increased when
canned foods are stored at higher
temperatures. For example, about a
third of the vitamin C is lost if foods
are stored a year at temperatures of
80° F (26° C) or higher.
Storage temperatures between 50°
to 70° F (10° to 21° C) are acceptable.
Properly canned and stored foods
should be safe to eat for more than
two years. However, for top quality,
it is best to can only the amount to
be used in one year.
Top quality home canned foods
have rich, jewel-like colors, characteristic
of the food canned. Colors are
those of well-prepared foods ready to
be served, rather than fresh uncooked
foods or over-cooked foods. Light-colored
foods should retain their
color with no signs of darkening at
tops of jars. Fruits should look neither
under-ripe and hard, nor over-ripe
and mushy. Vegetables ought to
look young and tender, rather than
308
old and starchy. Vegetables and fruits
should be free of stems, cores, seeds,
or pieces of skin, and be of uniform
size, shape and color.
Freezing, like canning, does not
improve food quality. Top quality
fresh fruits and vegetables are essential
for premium frozen products.
Quality factors include a suitable
variety for freezing, optimum maturity,
and freshness of the product.
Even with high quality, fresh produce,
it is imperative to freeze foods on the
day when they are at their peak of
maturity or ripeness for eating fresh.
Selection, sorting and trimming of
produce and the quality control steps
as related to color, flavor, and nutrient
retention described for canning
high quality fruits and vegetables
apply equally to preservation by
freezing. However, most vegetables
must be blanched before packaging
and freezing to prevent slow but accumulating
effects of enzyme activity
and autoxidation. These effects, if
not prevented, will cause discoloration,
oxidized flavors (sometimes described
as tasting grassy or hay-like),
and increased loss of vitamins, especially
A and C. Proper blanching recommendations
are contained in the
USDA Home and Garden Bulletin No.
10, Home Freezing of Fruits and
Vegetables.
The quality of packaging materials
used is reflected in overall quality of
the frozen product. Packaging materials
must be moisture-vapor-proof.
This means there is no transfer of
liquids or vapors from the inside to
the outside, or from the outside to the
inside of the frozen packages.
In addition, fruits and vegetables
must be packaged in containers with
as little air inside as possible. Air
left inside will oxidize the food, causing
deterioration of color, flavor and
nutrients.
Proper sealing is essential for packaging
quality frozen foods. If the seal
itself is not moisture-vapor-proof, it
becomes the weakest part of the package
and poorer quality results.
Adequate labeling helps assure that
each package of food is used while
at top quality. Packages kept too long
will be of poor quality. Even with the
finest produce and use of the best
preparation and packaging procedures,
retention of quality in frozen
food is affected by how quickly food
is frozen, the temperature of food
stored in the freezer, and how long
it is frozen before eating.
For top quality, avoid freezing per
day, more than two pounds of fresh
packaged food per cubic foot capacity
of your home freezer. Food packages
to be frozen should be spread one
package deep over the bottom or
other areas designated by your
freezer manufacturer. The freezer
should be regulated to a uniform
temperature between 0° F (-18° C)
and minus 5° F (-21° C). A freezer
temperature fluctuation of more than
5° F should be avoided if possible.
Freezing too slowly, temperatures
above 0° F, and temperature fluctuations
in freezers increase the ice
crystal size in frozen food, lower the
quality and shorten the shelf life of
food. Frozen foods should be used according
to the guidelines in the 1974
Yearbook of Agriculture, Shoppers
Guide.
Quality frozen fruits and vegetables
should have the natural color, texture
and flavor of the individual food.
There should be a minimum of ice
crystals inside the package and no
sign of freezer burn.
Frozen foods should be higher in
ascorbic acid and thiamin than
canned foods. Vitamin C, including
that leached into the juices, approaches
90 percent of the value of
raw fruits.
Quality fruits and vegetables can
309
be sun-dried or dried inside using an
oven or a food dehydrator. As with
other methods of preservation,
quality of the final product will depend
greatly on quality of the fresh
food being dried. Drying does not improve
the quality of any food.
A top quality dried product reflects
suitable pre-treatment before
drying, and adequate drying under
proper conditions. Also, appropriate
storage after drying is vital to keep
moisture from re-entering the dried
product.
Fruits may be dried more easily
than vegetables, because of their high
sugar content and since not as much
moisture must be removed to get a
quality product. When properly dried,
fruits should be leathery and pliable,
and have a color characteristic of the
fruit. Excessive darkening indicates
a less desirable, poorer quality
product.
Vegetables must be dried until they
are brittle. The color should be characteristic
of the vegetable and not
excessively dark.
To sum up, nutrient content of
foods depends on natural differences,
control of deterioration, and handling
techniques of food preparation as
well as preservation. Therefore, overall
nutrient content of a specific fruit
or vegetable, whether fresh or preserved,
may be about the same.
Top quality, garden fresh foods,
served in season, provide the greatest
satisfaction when served fresh as
table-ready food. Individual preferences
for market fresh, frozen canned,
or dried food will differ. Since nutrient
content is nearly the same, the
choice is up to the consumer. Even
more important is the choice of vegetables
and fruits for a good diet.
Food editors of Farm Journal, How to
Dry Fruits and Vegetables at Home,
Countryside Press and Doubleday &
Company (Dolphin Books), 1975. $2.95.
Hamilton, Louise W., Kuhn, Gerald D.,
Rugh, Karen A., with the food editors
of Farm Journal, Home Canning—The
Last Word, Countryside Press and
Doubleday & Company (Dolphin
Books), 1976. $2.95.
US. Department of Agriculture, Home
Canning of Fruits and Vegetables,
H&G Bul. No. 8, on sale by Superintendent
of Documents, U.S. Government
Printing Office, Washington,
D.C. 20402. 45¢.
U.S. Department of Agriculture, Home
Freezing of Fruits and Vegetables,
H&G Bul. No. 10, on sale by Superintendent
of Documents, U.S. Government
Printing Office, Washington,
D.C. 20402. 75¢.
310
Economics of Home Food Preservation, or Is Do-It-Yourself Back to Stay? — Time, Energy Costs — Cost of Home Food Preservation
Back-to-basics may turn out to be
the theme song of the 1970’s as some
of the simple activities of the past are
rediscovered and practiced. Do-it-yourself
is in. Nowhere is the trend
more apparent than in the area of
home production and preservation of
the family food supply. Ten years ago
no one would have dreamed the lowly
canning jar lid would be the subject
of Federal hearings. No one would
have believed that an estimated one
in four U.S. families would be raising
and preserving a portion of their
food supply.
What motivates people to return to
home food production and preservation?
Are their expectations realistic?
How extensive is their gardening?
Will they continue a second year? Do
they preserve any of their crop?
These were among the questions
posed by Stuhlmiller, How and Stone
of Cornell University in 1975 to a
group of gardeners in five upstate
New York counties.
When asked whether they gardened
to save money, to have better quality
food or just for a hobby or recreation,
three-fourths of the 2,800 who
replied hoped to save money, 54 percent
considered gardening a hobby,
while only 46 percent gardened for
fresher food. Most said they preserved
at least some of the food they
grew.
If this study is indicative of the
country as a whole, it is important to
realistically assess whether home
food production and preservation can
save substantial amounts of money
and whether the satisfaction gained
warrants the cost of time and energy
expended.
The actual costs of home food preservation,
for example, should be considered.
The cost of home grown food
should be compared to the cost of
similar food purchased for preservation
in quantities at local farms or
markets. The quality of the home preserved
items should be realistically
analyzed against readily available
commercially preserved food.
There is no such thing as free food.
Someone, somewhere, has to pay for
it in time, energy, know-how, and at
least some outlay of dollars. Home
production in amounts needed for
food preservation requires a longtime
commitment of family resources. Beginners
should realize that realistic
goals and reasonable skills in the field
and kitchen are essential to make
home preservation pay off.
There are no general statistics citing
the average dollar-cost needed to
grow a given amount of fresh produce
in a home garden. Conditions between
individual gardens, weather,
soil type, skill of operator, and geographic
areas vary too much for
valid comparisons.
Extension specialists at Michigan
State University, however, have computed
the actual cost of raising tomatoes
under home gardening conditions
in East Lansing, Mich. They
found it costs 12¢ to grow the amount
of tomatoes (2½ to 3 pounds) needed
for one quart, canned. A similar cost
analysis for green beans showed that
beans cost 30¢ for the amount needed
for a quart. Only the expendable cost—seed,
fertilizer, pesticides and water—was
considered.
Adding the expense for needed
tools, hoses and other capital items
raised the cost another 33¢ a quart
if the cost were absorbed in one season
or 2¢ if amortized over a 20-year
311
period. Unfortunately, the first-year
gardener will find that the outlay for
tools must be spent the first year so
that return for the investment requires
a commitment to gardening
over many years.
Additional expenses are necessary
if the bounty is to be preserved at
home. Equipment for preserving tomatoes
is minimal but equipment for
canning vegetables and for freezing
may be costly. Homemakers needing
to invest in canners, a pressure canner,
and home freezer will find that
the dollar cost per package of food
preserved during the first years of
preservation may be higher than the
cost of comparable food at the corner
supermarket.
The costs of canning peaches, tomatoes
and green beans in upstate
New York were calculated by the author
in 1975 and updated for price
changes in 1976 using a number of
different cost variables. She found
that those who canned tomatoes could
realize substantial savings, while the
cost of purchasing peaches and preserving
them at home approximated
the cost of the commercially canned
peach.
Determinations of the true cost of
frozen food must consider the initial
cost of the freezer plus the cost of
operation and repair. Containers,
plastic bags and boxes, or foil are
additional costs.
Evelyn Johnson in her Outlook Talk
of 1975 quoted staff at Virginia Polytechnic
Institute and Cornell University
as reporting a cost of 20¢ to 24¢
per pound of food frozen just for the
convenience of freezing and storing
food at home. Add to this the price
of the food being frozen for the
correct cost of home-preserved frozen
food.
Freezing is probably the most satisfactory
method of home food preservation,
the most versatile and the
easiest to do. But for all except the
very best managers who use the
freezer intensively, the home freezer
is more a convenience than a money
saver.
Needed equipment for home canning.
Left, water bath canner, and right, pressure
canner.
Raising a garden takes time over a
significant number of months. As a
hobby for table use, gardening can be
a real pleasure. Skillful persons with
the right tools and know-how can
handle a garden of the size needed
for home food preservation with a
few hours of work a week, once the
plants are well established. Novices
can expect to spend a significantly
greater amount of time per week during
the four or five month growing
season in northern areas and even
more in areas with longer growing
seasons.
The author, an experienced gardener,
kept records of the hours spent
cultivating and harvesting a 20 by 40-foot
garden, planted primarily for
fresh consumption. Only three foods—tomatoes,
green beans and cucumbers—were
raised in amounts sufficient
for a limited amount of home
preservation. Over 40 person-hours
were required. The actual grocery
store value of the garden food consumed
by the family of three was
$45. Food given as gifts and preserved
raised the dollar value to $75.
Gardening often helps stretch cash
income, but the dollar return is low
for hours of effort. And poor weather
may cause crop failures and small
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yields, regardless of effort. Food preservation
also is time-consuming.
Satisfactions. Why garden or preserve
food at home? Most gardeners
will cite a number of reasons:
—The best of good fresh food with no unknown additives or ingredients
[A]Some (such as quick dill pickles) are quick to make, take little effort, and use inexpensive ingredients. Others require prolonged brining over several days’ time plus expensive sugar and other ingredients.
There is no one right answer to
the question, “Does it pay to raise
and preserve my own food?” It depends
upon your personal goals. You
may not save a significant number of
dollars. You will work hard. And you
probably will experience one of the
most exciting activities possible—raising
at least some of the food your
family uses.
“We grew it” are heady words
which bring people back to home
food production and preservation
year after year.
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Beginner’s Guide to Home Canning — Low and High Acid Foods — Canning Jars — Work Fast — Packing Methods — Water Bath — Pressure Canner — After Processing — Label and Inventory
Canning is probably the most economical
and practical method of preserving
food at home. Among other
things it is a way to save food that
otherwise might be wasted.
Cost of home canning depends on
the kinds and sources of food canned
as well as the processing methods,
containers, and equipment used. Other
cost factors—labor, energy, water and
added ingredients—make exact cost
figures impossible to apply generally,
but studies are reporting averages
that show canning to be economical.
The wise homemaker will can only
the amount to be used within a year.
Food held longer will be safe to eat
if it has a good seal and no signs of
spoilage, but there may be nutrient
or quality loss, especially if stored
at temperatures above 70° F.
As a beginner canner you need to
know something about micro-organisms,
including yeasts, molds and
bacteria, on the food, in water, air and
soil, as causes of spoilage in foods.
Knowing about these minute forms
of life, which are so abundant everywhere,
will help make the work safer
as well as more interesting.
In addition to the action of these
minute organisms, the spoiling of
fruits and vegetables is hastened by
natural changes in color, flavor and
texture of the food. These changes result
from the action of enzymes or
micro-organisms found in nature
which break down and decompose
foodstuffs.
Bacteria are the most serious foes
to combat in canning because they
are more difficult to kill by heat than
either molds or yeasts.
Acid in canned food is expressed
as pH value. Foods having a pH of
4.5 or lower are called high-acid foods
and those with a value of 4.6 or higher
are termed low-acid foods.
Since few bacteria thrive in acids,
their destruction is less difficult in
fruits than in vegetables (with the
exception of tomatoes).
Botulism is a deadly poison caused
by a toxin from the growth of spores
(seeds) of the bacteria, Clostridium
botulinum. These spores will produce
a deadly toxin in low-acid foods in
the absence of air (oxygen) inside a
sealed jar. Therefore, the spores must
be destroyed by processing under
pressure at 240° F. The length of time
has been determined by scientists for
each individual food.
Clostridium botulinum will not grow
in foods with a pH of 4.5 or lower, so
high-acid foods may be processed
safely in boiling water at 212° F.
Low-acid vegetables
Asparagus
Beans—snap or shelled
Beets
Carrots
Corn
Potatoes
Pumpkin
Squash
Sweet potatoes
High-acid fruits and vegetables
Apples
Apricots
Berries
Cherries
Grapefruit
Peaches
Pineapple
Rhubarb
Tomatoes
Yeasts, mold and non-spore forming
bacteria are readily controlled by
processing at 212° F.
Most canning equipment and supplies
may be purchased at hardware
stores, housewares departments, and
from mail order companies. Jars and
lids are available in many retail
stores.
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Select standard canning jars made
of tempered glass that can withstand
high temperatures. The manufacturer’s
name or symbol in glass will
identify the product. With careful
handling, jars last an average of about
10 years. Avoid using antique jars
because there can be hair-line cracks
not visible to the eye, causing jars
to break.
Use canning jars in sizes suitable
for the product canned and your family’s
needs. Canning jars generally are
sold in half-pint, pint and quart sizes
with wide and narrow mouths. Large-mouth
jars are convenient for packing
such foods as whole tomatoes and
peach halves. Quart jars are convenient
for vegetables and fruits
where your family has four or more
members.
Examine the sealing edge of jars
for nicks, cracks, or sharp edges that
would prevent a seal. Discard any
with these imperfections.
One-trip jars from purchased
canned foods should not be used because
they generally are not tempered
to withstand the high heat required
for home canning, and may
break when subjected to the heat.
Tops of these jars may not fit standard
canning lids, thus preventing a
good seal.
Home canning equipment.
Closures—jar lids and rings come
with new canning jars. The sealing
compound of lids recommended for
one use only will not hold a seal
effectively after the first use.
Select lids appropriate for the jars
being used. You may find the two-piece
units (flat lid with sealing composition
and ring), one-piece lids, or
flats with separate gaskets made of
metal or plastic. Always follow the
instructions for pretreatment as indicated
on the box or container by
the manufacturer. If no name is indicated
on the lid, use a black wax
marking pencil or crayon and mark
the identity on each lid. If there are
problems, contact the manufacturer
whose name and address is on the
box or container.
Screw ring bands may be reused if
kept clean and dry in a protective
container with a tight-fitting lid.
Never use bands with rust, or pried
up or bent edges.
If you have extra lids, store them
protected in a dry, cool place.
One-piece zinc caps lined with
white porcelain, with rubber rings,
may be used. The caps may be reused
if they have not cracked, spread or
bent at the edges and are clean, like
new. The rubber rings are effective
only once because they tend to dry
and deteriorate with age, often become
porous, and sometimes crack.
If you have jars with bail wire
clamps, sometimes called “lightning”-type
jars, be sure they are not in the
“antique” class. Lids for these jars
are all glass, and rubber rings are
used between the jar and lid for sealing.
A wire clamp holds the lid in
place during processing; after processing,
the short spring wire of the
clamp is snapped down to complete
the seal.
A boiling water bath canner is
needed for processing high-acid foods,
such as fruits, tomatoes, tomato and
fruit juice, and pickles.
Water bath canners in several sizes
are available on the market. The container
must be deep enough for a rack
315
to hold the jars off the bottom of the
canner. The depth allows water to be
over the jars of food by at least 1 to
2 inches. Keep 1 to 2 inches of space
above the water to allow for boiling;
this prevents water from boiling over.
The canner must have a tight-fitting
lid. Or you can use a large
kettle with a tight-fitting lid, and a
wooden or wire rack to hold jars off
the bottom. There should be free circulation
of water to every part of
the surface of the jar and lid.
If you are going to buy a water bath
canner, check the height, and the lid
to be sure it is tight-fitting. The rack
preferably should have dividers so
jars will not touch each other or fall
against the sides of the canner or
each other during processing.
A steam pressure canner is absolutely
essential in canning low-acid
foods, such as vegetables, and insures
the destruction of spoilage micro-organisms.
Ten pounds pressure is used for
processing food in standard canning
jars at sea level. This pressure corresponds
to 240° F.
The steam pressure canner is made
of heavy metal that withstands high
pressure developed by steam. It consists
of a kettle with a tight-fitting
lid equipped with an accurate weight
or dial gage to register the pounds of
pressure in the canner. The lid must
lock or seal to prevent escape of
steam.
The canner must have a safety
valve, petcock or steam vent that can
be opened or closed to permit exhausting
(venting), and a pressure
gage. It must have a rack to hold
jars at least ½ inch from the bottom
of the canner.
A dial gage indicates pressure on
a numbered instrument.
A weighted gage has no dial, but
automatically limits pressure with
weights preset for 5, 10, and 15
pounds pressure.
Scalding tomatoes in a blancher.
The pressure is adjusted for high
altitude. For information on canning
at altitudes above sea level, see the
later chapter by Carole Davis.
To insure the canner’s proper working
condition, check the dial gage for
accuracy each year—or if a canner or
lid has been roughly handled or
dropped, the dial gage glass broken,
or any parts are rusty. The manufacturer
or your county Extension office
can give information on testing availability.
Study and follow the manufacturer’s
directions for using your
pressure canner.
Run through the process of operating
the pressure canner on your range
in a trial run before you get into the
canning season, to be sure everything
is working properly. Make a note of
the dial setting of the range if you
use an electric range for holding pressure
steady.
Trying to use a pressure canner
obtained from garage, rummage, or
auction sales or handed down to you
from someone’s attic may prove dangerous.
316
You may not have any idea
as to the care, handling, or storage of
the canner. A manufacturer manual
on care, use and replaceable parts
usually is not available. Old-old canners
did not have complete information—manufacturer’s
name, address
or model number—on the appliance.
General kitchen equipment is helpful
in any needed washing, peeling,
coring and slicing in the preparation
of fruits and vegetables. Examples
are, a vegetable brush for cleaning
vegetables, a blancher or wire basket
for scalding fruits and vegetables
such as tomatoes and peaches to
loosen skins for peeling, and a colander
for washing delicate fruits
such as berries.
A food mill is handy for making
purees and straining fruits for making
juices, and a strainer for straining
juice. A long handled fork or plastic
spatula aids in fitting and packing
food and removing air bubbles. A
wide-mouth funnel is very convenient
for filling jars, and a jar lifter helps
you avoid burns in handling hot jars.
Use an automatic timer to time processing
accurately.
The number of pints of preserved
food you will get from a given quantity
of fresh food depends on the
quality, variety, and maturity of the
fruit or vegetable; on the size of the
pieces, and on the packing method
used.
Selection of good sound fruits and
vegetables is of paramount importance.
The quality of canned fruits
and vegetables will be no better than
quality of the raw food used. For best
flavor retention, preserve only those
vegetables that are young, tender,
and freshly gathered.
All steps, from beginning to end, of
any lot of canning should be carried
through as rapidly as possible. A good
slogan is “two hours from harvest to
container”.
Work fast with small amounts of
food at a time, especially vegetables
with high starch content such as corn
and peas which lose quality rapidly.
Any delay will result in loss of flavor
and nutritive value.
Sorting and grading should be done
very carefully, according to size and
degree of maturity and ripeness.
Use only uniformly well-ripened
products. Discard all defective products
and use together those of the
same size.
Dirt in seeds, bits of food, or sirup
contains bacteria that is hardest to
kill, and encourages yeasts and molds
to grow on the outer surfaces. Wash
fruits and vegetables thoroughly before
canning.
Scalding, peeling and coring—some
fruits, such as peaches and tomatoes,
are scalded in order to peel them
smoothly.
Follow up-to-date recommendations,
available in U.S. Department of
Agriculture or Extension publications,
for detailed procedures in preparing
fruits and vegetables for canning.
You can pack food hot or raw in
jars. Hot-packed food is heated thoroughly
before it is packed into jars.
Raw-packed food is placed raw in
jars. Watery and soft foods such as
tomatoes are pressed gently to make
their own juice.
Air, a poor conductor of heat,
should be removed from the jar. Remove
air bubbles by gently moving
the blade of a plastic spatula or
plastic knife around the jar—being
careful that the food is not broken.
Add more boiling liquid if necessary
to get a proper fill.
When filling jars, you will find the
jar-filling funnel easy to manage. This
makes it possible to avoid spills of
seeds, bits of food, or sirup that
could prevent sealing. But even when
using a funnel you still need to wipe
the jar rim.
317
Heating beans thoroughly before placing
them in jars. Here, cut beans are
covered with water to be followed by
five minutes of boiling.
Prepare the lids and sealing of jar
according to the manufacturer’s directions.
When using a flat metal lid,
place the composition side on the
rim of the jar. Add the ring band and
screw it down until firm, but not hard
enough to cut through the sealing
compound. The lid will have enough
“give” to let air escape during processing.
This is called venting and
means heating to remove air from
jars.
When using porcelain-lined zinc
caps, fit the wet rubber ring on the
jar shoulder, but do not stretch it
more than necessary. Screw the cap
firmly and turn it back ¼ inch.
Use a jar lifter or tongs and place
the filled jars on the rack in the
canner. Fill and place jars in the
canner one at a time to keep jars as
hot as possible while filling the
canner.
Before you begin preparing the
food, fill the water bath canner half
full of hot water. This permits water
to heat while you prepare the food.
Put a large kettle or teakettle of
water on to boil. The water should
be boiling when hot-pack food is put
into the canner.
Place raw-pack jars in water that is
hot (180° to 190° F), just below boiling.
Then bring it to a boil after
adding jars.
As the rack of jars is lowered into
the water, the water level will rise. If
more water is needed to have the jars
completely covered by 2 inches of
water, add boiling water.
Prepare only enough jars of food at
one time to fill the canner. Work
rapidly, allowing as little time as possible
between filling and closing the
jars and getting them into the canner.
Start counting processing time as
soon as the water in the canner
reaches a gently rolling boil. Put the
lid on the canner. Set your timer or
clock and make a written note of
starting time and final time. Keep the
water boiling all during the processing
period. If water boils down, add boiling
water sufficient to keep it at the
required height. When pouring water,
avoid letting it hit tops of the jars.
Process for the recommended length
of time. Do not cut processing time.
Follow the manufacturer’s directions
for operation of your pressure
canner before, during and following
processing. Supplement these directions
with information in U.S. Department
of Agriculture or Extension
publications.
Count processing time as soon as
the pressure reaches 10 pounds or
the proper pressure adjusted for altitude.
Be sure to hold pressure steady.
At end of the processing time, remove
the canner from the heat. Allow
the canner to cool until the gage
registers zero to avoid breakage of
jars and loss of liquid from jars. After
a minute or two, open the petcock
318
gradually and remove the cover. If a
weighted gage is used, nudge the
weight slightly. If no steam escapes,
pressure is down. Tilt the far side of
the lid upward so steam escapes away
from your hands and face. Because
food in the jars may be boiling vigorously,
leave jars in the canner about
five minutes and then remove them.
When you remove hot jars from
the canner, use a jar lifter, or protect
your hands with cooking mits, pot
holders or canvas gloves. Set the jars
upright to cool on a rack, such as a
cake rack, or a bread or cutting
board, with double layers of dry cloth
or newspapers beneath the jars. If
jars are placed on a cold surface or
wet cloth, the difference in temperatures
may cause the glass to crack.
Avoid placing jars in a draft, but
leave two or three inches between
them so air can circulate freely. Avoid
further tightening of lids that have
sealing compound, since this usually
breaks the seal—unless the lid manufacturer
states it is safe to tighten.
If your processing temperature was
not held steady and liquid boiled out
in processing, do not open the jar to
add more. Leave the sealed jar just
as it is.
Do not cover jars because this
slows down cooling and food continues
to cook. If you have an air
conditioning vent that will direct cold
air on jars, cover the vent during this
canning session.
After 12 hours, check the seals. The
vacuum may cause a loud snap of the
two-piece vacuum seal while it cools,
which is an indicator of an airtight
seal. If the center of the lid holds
down when pressed and the lid does
not move, it is sealed.
Tap the center of the lid with a
spoon—a clear, ringing sound indicates
a good seal; a thudding sound
indicates the possibility of an imperfect
seal.
If there is a sealing failure, you will
need to reprocess the jars. Remove
the lid, heat the food and liquid, fill
a clean jar and use a new lid. Process
the full length of time. If only a few
jars did not seal, you may elect to
refrigerate and use the food within a
day or two or freeze it.
Once the jar is sealed, allow it to
set until cold. Then remove the
screw ring band, wash and store in a
dry place for reuse. For safety make
a routine check of canned foods each
month.
Write name of product and date
canned on a gummed label or the lid
of each jar with a felt tip pen. Keep
a record of food canned, date, number
of quarts or pints, and a place
for you to check them off as you use
them. This can be your guide for next
year’s preservation plan. Use food
preserved for the current year, readying
a storage place for next season’s
garden produce.
Canned foods stored in a dry, dark,
cool temperature (70° F or below)
will retain good eating quality for a
year. Home canned foods stored in a
warm place near direct sunlight, hot
pipes, above a range or refrigerator,
or in kitchen cabinets may lose some
eating quality within a few weeks.
Dampness may corrode lids and cause
leakage so that the food spoils.
The main cause of spoilage in
canned foods is improper processing.
Bulging jar lids, or a leak, may mean
gas is present and the food spoiled.
Before opening home canned foods,
wash jars and lids and carefully inspect
the jars. Bacteria, yeasts and
molds should have been destroyed if
the food was properly processed.
When you open the container, look
for such danger signs as spurting,
cloudy or frothy liquid, an “off” odor,
deterioration, or slimy texture. A
foamy or murky appearance and
patches of mold are visible signs of
319
spoilage. That ordinary looking mold
on home-canned food may indicate
the presence of a much more deadly
problem: botulism.
ALWAYSlabel home-canned foods.
Destroy food if any of these signs
are obvious; discard out of reach of
humans and animals.
The odor in good jars of food
should be pleasant and characteristic
of the product. Do not use food which
looks or smells bad, or if there is any
doubt as to its safety.
All low-acid, home-canned food
should be boiled 10 to 20 minutes to
insure destruction of botulism-causing
toxin for added safety. Heating denatures
the toxin so that it does not
react with the body. Never taste home
canned food before cooking it.
Successful results largely depend
upon the accuracy with which up-to-date
directions are followed.
Safety is best assured when you
exercise special care as you prepare
and pack food into canning jars,
fitting jars with properly pretreated
lids, and heating jars of food to a high
enough temperature for a sufficient
length of time to kill micro-organisms
that cause spoilage.
320
A Primer on Home Freezing for the Beginner — What Freezing Does
Every homemaker knows that meals
must be planned to get the most out
of the food dollar and to provide the
family with a well-balanced diet. The
freezer, more than any other household
appliance, can help secure these
results. The more you learn how to
use it in relation to your own family,
the greater the returns.
Freezing is a quick, convenient and
easy way to preserve foods in the
home. Plan ahead to manage your
time and energy for preserving food
directly from harvest. Freeze limited
amounts at one time so the work is
spread over several days of picking,
rather than squeezed into one long
tiring period of time. Be practical
about what you attempt.
Your own observation has taught
you that some foods “spoil” more
quickly than others, so the rate of
speed at which they must be frozen
varies with their individual temperaments.
A good rule for home freezing
is: two hours from garden or orchard
to container, and the faster the better!
Most food that is highly perishable
at normal temperatures can be quick
frozen. Even delicate fruits and vegetables
can be frozen, with only a few
exceptions such as tomatoes (stewed
tomatoes can be frozen) and those
vegetables that lose crispness such
as radishes, celery, cucumbers and
salad greens.
Decide what you will freeze on the
basis of availability of foods, family
needs and taste, freezer space, cost
of freezer storage, and availability of
alternate methods of storage.
It is essential to start with high
quality raw material. As garden foods
mature, process without delay. Quality
of the frozen food will be only
as good as the quality of the food
before freezing. Freeze foods at their
peak of eating quality to preserve
flavor, texture, and appearance as
near those of the fresh product as
possible.
Do not ignore details of the recommended
procedures for preparing
foods for freezing. Seemingly unimportant
steps can make the difference
between a low quality and a superior
frozen product.
Before you begin freezing foods at
home it’s important to know exactly
which process to use and what the
process is doing to the food.
Micro-organisms grow on food,
causing it to spoil. The common
growths are simple yeasts, molds, and
bacteria. Because these micro-organisms
are everywhere—in the air, water,
soil and on all surfaces they
contact—they naturally occur on all
foods. Storing and preserving foods
properly controls or inhibits the
growth of micro-organisms, thus
maintaining both quality and safety
of the food.
Cleanliness and sanitary methods
are as important in handling foods for
freezing as in preparing them for
immediate use.
All foods contain chemical substances
called enzymes. They are essential
to life, and continue their
chemical activity after the fruits and
vegetables mature or are harvested.
If allowed to work after a food
reaches its peak of maturity, enzymes
destroy the food’s physical properties,
thus changing its color, flavor
and texture.
When perishable food is not preserved
by one of the recommended
ways, enzymes within the cells of the
food continue to live and cause spoilage.
321
Freezing and storage even at very
low temperatures will not inactivate
any of the common enzymes. At 0° F,
the recommended temperature for
storing frozen foods, enzymes are
not inactivated but only slowed down.
In two to three months they will produce
off-odors and bad taste. This
temperature only checks the growth
and reproduction of destructive bacteria.
The faster a food is properly
prepared frozen, the sooner both
enzymes and bacteria are rendered
harmless.
Just about every kind of food you
or I will freeze contains moisture or
water, and the process of freezing
food involves the freezing point of
water. As temperature of the surrounding
air goes below the freezing
point of water, the water progressively
crystallizes out in the form of pure
ice. Size of the crystals which form
is determined by the span of time
during which freezing takes place.
When the temperature is lowered
slowly, the crystals expand considerably.
If the freezing is sharp and
sudden, the crystals retain approximately
the same size as the original
water molecules.
In case you have doubts about how
well a food will freeze, test it before
freezing large quantities. To test,
freeze three or four packages and
sample the food a couple of weeks
later. This will show the effect of
freezing but not the effect of storage.
Some varieties of the same kind of
food freeze well, others do not.
Much of the success you have with
your home freezer will depend on
how you prepare, package, wrap and
seal foods. Protecting frozen food is
as important as freezing food of high
quality.
You will need general kitchen utensils
plus a steel, aluminum or enamel
kettle large enough to hold at least
one gallon of boiling water, with a
tight fitting cover. Use a mesh basket,
a strainer, or large squares of cheesecloth
to hold one pound of vegetables
in the boiling water.
Steaming of cut, sliced or green
leafy vegetables is recommended and
will preserve more nutrients than
water does.
You will need a container to hold
ice water for quick chilling of vegetables
to stop cooking action. Drain
thoroughly in a colander and turn out
on absorbent towels.
It is false economy to skimp on
wrappings and containers. They
should protect the food from cold air,
which is dry, so as to retain the
moisture in foods and prevent freeze
burn and dehydration. Select them
according to the use they will be
put to.
Most freezer containers on the market
today are easy to seal, waterproof,
and give satisfactory results. Rigid
plastic containers, bags, and jars with
wide tops are favorites.
Moisture- and vapor-resistant
wraps, which are exceptionally effective
at excluding oxygen, include
heavyweight aluminum foil, coated
and laminated papers, polyethylene
films, saran, and polyester films. They
should be strong and pliable so the
wrap will adhere readily to irregularly
shaped objects, and eliminate as
much air as possible to avoid frost
accumulation inside. Careful wrapping
is of no avail if the package
breaks. It should be easily sealed,
either by heatsealing or freezer tape.
Freezer bags are available, and
freeze-and-cook bags that withstand
temperatures from below 0° F. to
above the boiling point. The freeze-and-cook
bags are suitable for freezing
and reheating food. Points to consider
include the size convenient for
your use and the cost.
Materials not moisture-proof and
vapor-proof, and thus not suitable for
packaging foods to be frozen, are
ordinary waxed papers, cartons from
ice cream or milk, and plastic cartons
322
from cottage cheese or gelatin products
because they crack easily.
Compare price, durability, shape
and reusability in selecting containers,
keeping in mind their convenience
and the economical use of freezer
space.
Retaining the vitamins and other
nutrients depends on how fruits and
vegetables are handled before freezing,
on storage temperature in the
freezer, and on how you cook them.
Always follow up-to-date recommendations
available from the U.S.
Department of Agriculture or county
Extension office.
Select foods of top quality. A freezer
is not magic—it does not improve
food. Its function is to preserve quality
and food values and to prevent
spoilage.
Choose vegetables and fruits suitable
for freezing, and the best varieties
for freezing. Because growing
conditions and varieties vary greatly
across the country, check with your
county Extension office to find out
which varieties are best for freezing.
Freeze fruits and vegetables when
they are at their best for table use.
If possible, freeze those that are ripened
on the tree, vine or bush. Fruits
should be ripe but firm.
Enzymatic changes continue after
harvest, lowering quality and nutritive
value. If stored at too warm temperatures,
fruits can lose vitamin C,
turn brown, lose flavor and color, and
toughen.
Don’t delay in harvesting vegetables
since asparagus, corn, peas,
snap beans, and lima beans all deteriorate
rapidly in the garden after
reaching their peak.
Observe cleanliness while you
work, to avoid contaminating foods.
Prepare vegetables for freezing by
blanching them in boiling water for
recommended times. County Extension
offices will have information on
specific times for various foods.
Blanching vegetables is absolutely
necessary to inactivate enzymes that
cause undesirable changes in flavor
and texture. This brief heat treatment
reduces the number of micro-organisms
on the food, enhances the green
color in vegetables such as peas,
broccoli and spinach, and displaces
air trapped in the tissues.
Pack food in containers as solidly
as possible to avoid air pockets, leaving
the necessary head space for expansion.
Press out as much air as
possible, with your hands or by using
a freezer pump. Then seal the plastic
bags by twisting the open end, folding
it over. Freezer rubber bands,
twist-seals, or freezer tape are satisfactory
for sealing bags.
Label packages clearly and carefully
with name of product, date
when frozen, number of servings or
poundage, and any information that
will help you. Special pens are made
for marking frozen food products. Or
you can use a wax pencil or crayon.
Speed is important in preparing
food and getting it into the freezer,
so as to maintain quality. Put only
the amount of unfrozen foods into the
freezer at one time that will sharp
freeze within 24 hours.
Allow at least one inch between
packages of unfrozen food in the
freezer for circulation of cold air.
Leave packages in freezing position
for 24 hours before stacking them
close together.
Uniform freezing temperature and
keeping frozen products at 0° F or
lower will maintain quality. Different
foods have varying storage periods,
so keep your frozen food inventory
changing.
Use a freezer thermometer in your
freezer. Check your freezer door and
wall plug daily to avoid any catastrophe.
A freezer can pay wonderful dividends
with considerable thought and
planning by the homemaker.
323
Pressure Canners, Vital for Low-Acid Foods — Fruit and Vegetable Acidity — How Food Is Heated — Pressure Canners — Effect of Altitude
Use of a pressure canner for preserving
low-acid foods is not new.
Pressure canners for home canning
were first marketed in the early
1900’s. In 1917, the U. S. Department
of Agriculture announced that use of
a pressure canner at 10 pounds pressure
(240° F) was the only safe
method for canning vegetables. Today’s
recommendations are essentially
the same.
A temperature of 240° F or 10
pounds pressure at sea level is needed
to kill spoilage organisms in a reasonable
time, especially the spores of
Clostridium botulinum. These spores,
if not killed, can produce the most
deadly toxin known to man.
The commercial canning industry
stringently follows safe canning practices.
Their safety record is excellent.
A Complete Course in Canning by
Lopez (1975) says that since 1925 four
deaths have been reported from the
consumption of more than 800 billion
cans of commercially processed
foods. The record for home canning
is much worse—450 deaths in a fraction
of the number of cans. Unsafe
practices were probably used in preserving
the deadly home-canned food.
Methods like open kettle, oven, and
boiling water bath canning for low-acid
foods are not sufficient to kill
Clostridium botulinum spores. Educators
talk to many people even today
who still use unsafe practices because
“that’s the way my mother always
did it”, or because they are unfamiliar
with pressure canners.
In this chapter, the need for safe
pressure canning procedures will be
discussed along with the rationale for
using care in preparing low-acid
foods for canning.
Acidity of a particular food is the
most important factor in determining
which canning method should be used—pressure
or boiling water bath.
Acidity is measured and stated
much the same way we express length
or weight. Acidity (pH) refers to acid
strength, not the amount of acid
present.
For example, citric acid, an acid
found in oranges, grapefruit, and
other citrus fruits, is a weak acid
compared to hydrochloric acid, a very
strong acid. The measure used to express
acid strength is pH. The pH
scale runs from 1 to 14 with 7 as
the neutral point. Substances with pH
below 7 are called acidic, while those
above 7 are called basic or alkaline
foods. The lower the pH, the more
acid the food.
Acidity or pH of a food affects the
length of time it must be processed
at a particular temperature to make it
safe. The more acid the food (the
lower the pH), the shorter the time
required for processing.
Almost all foods are acid in nature.
Hominy is an example of a food that
is neutral or slightly alkaline.
Foods are further categorized as
high acid or low acid because the C.
botulinum spore will not grow at pH
levels of 4.6 or below. High acid
foods (pH 4.6 or below) include tomatoes
and all fruits except figs. (See
chart).
Those with a pH above 4.6 are the
low-acid foods. All vegetables except
tomatoes and those that have been
pickled or fermented are low-acid.
Safe processing times have been
established at 240° F for low-acid
home canned products, since at this
temperature the processing times are
reasonably short and texture of the
324
resulting product remains good. The
heat-resistant C. botulinum spore has
been known to survive many hours
of boiling at 212°. Once food reaches
240°, the spore is killed when held
for the recommended number of
minutes.
High acid foods
Lemon Juice
Cranberry Sauce
Gooseberries
Rhubarb, Dill Pickles
Blackberries
Applesauce, Strawberries
Peaches
Raspberries, Sauerkraut
Blueberries
Sweet Cherries, Apricot
Tomatoes
Low acid foods
Figs, Pimentos
Pumpkins
Cucumbers
Turnips, Cabbage, Squash
Parsnips, Beets, Green Beans
Sweet Potatoes
Spinach
Asparagus, Cauliflower
Carrots
Potatoes
Peas
Corn
Holding of produce to be canned
for long periods in warm summer
temperatures gives bacteria ample
time to multiply into vast numbers,
thus increasing the chances of spoilage.
For example, one cell can multiply
into a billion cells in just 15 hours of
holding under favorable conditions.
Salt and spices added to low-acid
canned products in amounts recommended
do not appreciably alter
processing time. Salt may slightly
lower the heat resistance of some
micro-organisms but not enough to
present a problem if omitted for
dietary reasons.
Fats and oils, if added, may reduce
the rate of destruction of bacterial
spores. Spores of C. botulinum have
been known to survive beyond all
reasonable expectation when heated
in oil suspensions. Thus, adding oil
or fat to a product being canned
could be dangerous and is not recommended.
The type, consistency, and piece
size of food and how it is packed in
the jars are important factors which
affect processing time. In preparing
jars of food for the pressure canner,
follow directions carefully. Do not
use jars larger than the directions
specify.
Determining the safe processing
time for a food product involves two
important steps.
First, the rate of heat penetration
is measured by finding the spot in
the jar that takes the longest time to
heat. This is referred to as the “cold
spot”. Times will depend on the type
of food (squash vs tomato juice) as
well as how it is prepared (whole
kernel vs cream style corn).
The second step is done in a laboratory.
A known amount of some live
bacterial spores is put into the “cold
spot” of the jar of food. These jars
are then heated and the amount of
time needed to kill the spores is
determined.
Heat is a form of energy which
flows from hot to cold substances.
This flow occurs by convection, conduction,
and radiation. In a pressure
canner, convection and conduction
are the primary methods of heat
transfer.
Convection heating occurs in thin
liquids and in gases like air and
steam. As molecules are heated, they
become lighter and rise to the top of
the jar, displacing cooler ones
toward the bottom. This movement
is visible in water that is being heated
in a clear glass container. Convection
heating occurs best in liquids like
fruit and vegetable juices or broths.
These heat rapidly and thus have
shorter processing times.
Small quantities of starch either
added or leached from vegetables
slows down the convection and increases
processing time. For example,
jars of liquid containing pieces of
325
green beans or peas would heat more
slowly than apple juice because the
pieces would interfere with convection.
A tightly packed jar takes longer to
heat than a loosely packed one which
allows some convection heating. Thus
it is important not to over-pack jars
as this will decrease the rate of heat
penetration.
Some types of food heat by a combination
of conduction and convection.
One example is a peach half in
thin sirup. The sirup heats by convection
while the peach heats by conduction.
Another example is cream style
corn. Initially, the liquid is thin and
heats by convection. As the liquid
thickens, it heats by conduction.
Conduction occurs when heat is
transferred from one particle or substance
to another right next to it. This
is the slowest type of heat transfer.
Foods that mat together, like spinach,
or viscous material like mashed
pumpkin, heat by conduction. The
larger the pieces of food or the thicker
the puree, the slower the heat
penetration.
A pressure canner is a kettle made
from a material, usually aluminum,
that is strong enough to safely withstand
the pressures used in home canning.
The lid is built so it can be
locked to the base of the canner. On
one type, metal in the sealing edge
is ground smooth so little or no leakage
occurs between the lid and the
base. Care should be taken to avoid
damage to the sealing surfaces which
could ruin the canner.
Other canners have a gasket made
of a rubber-like substance that prevents
leakage of steam. The gasket
should be washed in hot suds, rinsed,
and dried thoroughly after use.
All pressure canners include a safety
plug or fuse. One type has a metal
fuse that melts when the temperature
is too high. If the canner is used properly
the fuse should never need replacing.
Another type of canner has a
rubber-like safety plug. Care should
be taken to replace the plug when the
rubber gets hard. As the rubber hardens,
it takes a greater pressure for
it to blow out. Some older type canners
have a petcock that serves as a
vent and safety valve.
In canners that have a pressure
gage, vents serve to exhaust air from
the canner. The air is exhausted by
venting for 10 minutes after steam
starts escaping. All the air must be
exhausted before the canner is sealed
because the steam has much more
heat energy. For example, air in a
212° F oven feels just warm while
212° steam from a teakettle will burn
you.
Be sure to read and follow the instructions
with your canner.
All canners should have some type
of rack in the bottom. A rack keeps
the jars from touching the bottom of
the canner and breaking. It also aids
in transferring the heat more evenly
within the canner by permitting water
and steam circulation.
There must be enough water in the
canner to provide steam throughout
processing. Two quarts of water is
usually recommended, although this
may vary depending on size of the
canner and the quantity of jars.
Pressure canners have either a dial
gage, a pressure control or a combination
of these. The dial pressure
gage indicates the pressure and corresponding
sea level temperature. The
control type canner has a precision
weight that sits on the vent pipe and
jiggles to regulate pressure. A third
type is a combination gage and control.
The dial pressure gage measures
steam pressure. The tube in the pressure
canner gage operates like a New
Year’s Eve noisemaker, which is a
flat paper tube rolled up. Blowing
into the tube causes it to become
more round and unroll.
326
The pressure gage works the same
way except not as dramatically. The
gage is made of a partially flattened
metal tube. When pressure is applied,
the tube becomes more round and
straightens slightly. The needle [pointer]
moves as the tube straightens.
The gage is calibrated to indicate
pressure. Pressure is controlled by
adjusting burner heat to maintain the
desired pressure. This type of gage
should be checked yearly or after
suspected damage, such as dropping,
to be sure it functions properly.
A pressure control consists of a
precision weight that rests on a
specially designed vent pipe. It automatically
maintains an even pressure
and temperature inside the canner.
Pressure builds inside the canner
until the upward force (steam pressure
times seat area) is greater than
the downward force of the weight on
the seat area. At this point, the control
weight is lifted, releasing steam
and reducing pressure, until the upward
force equals the weight. The
pressure inside again increases slightly,
lifts the weight, and releases the
pressure.
The repeated lifting and reseating or
jiggling of the control weight indicates
that the pressure is being controlled.
The burner is adjusted so the control
jiggles at least several times a
minute. Excessive jiggling will deplete
the supply of water in the canner.
There are two types of pressure
controls. One type is a single weight
with 3 holes which fit on the vent
pipe. The diameter at the base of the
hole (seat area) is different for each
of the 3 pressures—largest for 5
pounds pressure, and smallest for 15
pounds pressure.
The second type has 1 seat area
and a 3-piece weight. For 5 pounds
pressure, the small center weight is
used. One additional ring or weight
is added for 10 pounds pressure, and
a second ring or weight is added for
15 pounds pressure.
With care, the pressure control remains
accurate throughout the canner’s
lifetime. Be sure that seat areas
where the weight and the vent pipe
make contact are not damaged or excessively
worn; this could affect the
canner’s performance.
The combination gage is not as
common as the other two types. It
has a sliding piston which pushes up
on a spring. As pressure inside the
canner increases, the piston is pushed
up. Rings on the piston indicate pressure.
If the heat is not regulated correctly,
pressure builds up to beyond
15 pounds, at which point the weight
is lifted to release the excess pressure.
It will jiggle audibly, indicating
to the user that the pressure is too
high. This system serves as a gage
as well as a safety device.
The combination gage should be
kept clean and dry when not in use,
to prevent corrosion. It also must be
checked yearly to be sure the piston
slides easily and indicates the correct
pressure.
Atmospheric pressure is like the
thickness of frosting on a cake. Where
it is thickest it weighs more per
square inch than where it is thin. At
sea level, where the atmosphere is
the thickest, it is heavier than atop
a mountain.
As altitude increases, atmospheric
pressure or its weight per square inch
decreases. Altitude affects the boiling
point of water. Where altitude is least,
at sea level, water boils at 212° F. As
altitude increases the boiling point of
water decreases.
The same is true in a pressure canner.
Under 10 pounds pressure at
sea level, water boils at 240° F. As
altitude increases, the temperature
in a pressure canner at 10 pounds of
pressure is less than 240°. This difference
is enough to affect the safety
of canned products at altitudes above
2,000 feet.
327
Fred Farout Processing times and pressures should
be adjusted for altitude change.
Processing time for a particular
vegetable is the time it takes to heat
the coldest part of the jar to a temperature
of 240° F, and maintain it
long enough to kill any C. botulinum
spores present. At an altitude of 2,000
feet, it takes 11 pounds of gage pressure
for water to boil at 240°. For
each additional 2,000 feet increase in
altitude, 1 pound of pressure should
be added.
For pressure canners that have the
pressure control, the 15 pounds pressure
weight should be used at altitudes
above 2,000 feet for canning
low-acid food.
At the end of processing, pressure
inside the jars as well as inside the
canner is 10 pounds. The pressure inside
the canner should be allowed to
drop slowly. If pressure inside the
canner is released too rapidly, pressure
inside the jars will be great
enough to force the contents, especially
liquid, out of the jars. This may
prevent a jar from sealing if a piece
of food lodges on the top of the sealing
rim. It may even break the jar.
Remove the lid from the canner as
soon as the pressure drops. Jars
should then be taken out and allowed
to cool to room temperature quickly.
A type of non-toxic spoilage called
flat sour can occur if the jars are allowed
to stand in the canner for long
periods.
When using the steam-pressure
canner, the pressure given is for altitudes
less than 2,000 feet above sea
level. If you live in an area with a
higher altitude, it is necessary to
make an adjustment in pressure. See
the next chapter for details.
328
Home Canning of Fruits and Vegetables — Altitude Corrections for Boiling Water Bath — Equipment — Selecting and Preparing — Processing Fruits — Processing Vegetables — Day-After Check — Look for Spoilage — How to Can Cut Green Beans [8] — How to Can Peaches [9]
Canning in the home is increasing
in popularity as a method of food
preservation. Economic considerations
are causing consumers to look
for ways to stretch their food dollars.
By having their own gardens and
canning the harvested produce, they
often can save money. Eating quality
of home-canned products encourages
some individuals to can. The activity
of growing or obtaining produce and
preserving it in the home sometimes
gives people a sense of personal
achievement and satisfaction.
In canning, food is preserved by
applying heat to prepared food in
containers so that micro-organisms
that cause spoilage or food poisoning
are destroyed and enzymes that
cause undesirable quality changes in
the flavor, color, and texture of food
are inactivated. Preservation of food
by canning also depends on sealing
the food in sterile, airtight containers
to prevent it from coming in contact
with micro-organisms in the environment.
Canning is not a difficult technique,
but it must be done properly to avoid
spoilage and food poisoning, such as
the often fatal botulism. It is extremely
important that only tested
reliable instructions are used, such
as those found in U.S. Department of
Agriculture publications. Based on
scientific research, specific instructions
have been developed for preparing,
packing, and processing each
food. Instructions should be followed
exactly from beginning to end—without
taking any shortcuts or altering
any recipes.
Acidity of the food is the chief
factor in influencing the time and
temperatures necessary for processing.
The more acid the products, the
easier spoilage organisms are destroyed
by heat. Acid foods—such as
tomatoes, fruits, and pickled vegetables—can
be safely processed at
the temperature of boiling water in a
boiling-water-bath canner. If spoilage
organisms are not killed by adequate
processing, they will continue to grow
and could reduce the acid in the
canned product, thus encouraging the
growth of more dangerous organisms,
such as Clostridium botulinum.
Low-acid foods—all vegetables, except
for tomatoes—require a more
severe heat treatment than acid foods
to kill the organisms. The only safe
way to can these foods is with a
steam-pressure canner, one with a
weighted or dial gage, to obtain temperatures
above boiling. Clostridium
botulinum is extremely dangerous in
these low-acid foods because if it is
present, and the heat treatment has
been insufficient, it can grow and
produce a deadly toxin in the sealed
containers.
Processing times are based on sea
level conditions where water boils at
212° F or, when under 10 pounds of
pressure, at 240°. As the altitude increases,
the temperature at which
water boils decreases. Therefore, at
altitudes above sea level you need
to make adjustments in canning instructions
to insure that foods are
adequately processed.
When using a boiling-water-bath
canner you must add more time in
processing, as given in the table.
At altitudes above sea level it takes
more than 10 pounds of pressure for
the temperature of boiling water to
reach 240° F.
When using the steam-pressure
canner, the pressure must be increased
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although the time remains
the same as that recommended for
sea level. At altitudes above 2,000
feet, process as follows:
Altitude
Pounds of pressure
2,000 feet
11
4,000 feet
12
6,000 feet
13
8,000 feet
14
10,000 feet
15
Increase processing time if the time recommended is:
Altitude (feet)
20 minutes or less
More than 20 minutes
1,000
1 minute
2 minutes
2,000
2 minutes
4 minutes
3,000
3 minutes
6 minutes
4,000
4 minutes
8 minutes
5,000
5 minutes
10 minutes
6,000
6 minutes
12 minutes
7,000
7 minutes
14 minutes
8,000
8 minutes
16 minutes
9,000
9 minutes
18 minutes
10,000
10 minutes
20 minutes
Use jars made especially for home
canning so the jars will be the right
size for the processing time and temperature
used, properly heat tempered,
and resistant to mechanical
shock. Always check jars before
using to be sure they do not have
nicks or cracks. Wash jars in hot,
soapy water and rinse well.
It is important to use standard jar
closures. They are designed to fit
home canning jars correctly, and are
made from suitable materials to provide
a proper seal. One of the most
popular types is the two-piece lid
with a metal ring or band and a flat
metal disk with a sealing compound.
Flat metal disks can be used only
once since they may not seal properly
if reused. Metal bands may be used
repeatedly if they are not rusted or
dented.
Screw ring band and disk.
Wash and rinse lids and bands.
Metal lids with sealing compound
may need boiling or holding in boiling
water for a few minutes; follow
the manufacturer’s directions. Porcelain-lined
zinc caps with rubber
shoulder rings can also be used to
seal jars. Rubber rings should be used
only once.
Water-bath canners are readily
available on the market. However,
any large metal container may be
used for a water-bath canner if it is
deep enough so the water is well
over the tops of the jars and has
space to boil freely. Allow 2 to 4
inches above jar tops for brisk boiling.
The container or canner must
have a tight fitting cover and a rack
to allow water to circulate under the
jars.
The steam-pressure canner is made
of heavy metal and has a cover which
fastens to make the pan steam-tight.
The cover is fitted with a safety
330
valve, a petcock or vent, and a gage—either
weighted or dial. All parts
of the canner must be clean and in
good working order. Check the gage
before the canning season, and also
during the season if canner is used
often. The weighted ones need only
be checked to determine if they are
thoroughly clean. A dial gage can be
tested for accuracy by a county Extension
agent or an equipment manufacturer.
A pressure saucepan may be used
for canning pint jars of food. However,
20 minutes must be added to
the processing time recommended for
a particular food canned with the
pressure canner. This is because pressure
saucepans heat and cool more
rapidly than pressure canners do.
Thus additional time is needed to
compensate for the otherwise reduced
exposure of the food to heat.
Home-canned foods will be no better
than the raw products with which
you begin. Fruits and vegetables
should be of good quality with no
bruises or soft spots. Be sure to
choose fresh, firm, ripe fruits and
young tender vegetables. Use them
before they lose their freshness. Do
not use overripe produce because
some foods lose acidity as they mature,
and the recommended processing
time may not be adequate.
Wash all fruits and vegetables
thoroughly, but gently, to remove dirt
which contains bacteria. Wash small
quantities at a time under running
water or through several changes of
water. Lift fruits and vegetables out
of the water so the dirt will not resettle
on the food. Do not let fruits
or vegetables soak, as they may lose
flavor and food value. Peel and cut
or slice produce as indicated in instructions
for each specific fruit or
vegetable.
Fruits and vegetables may be
packed raw into jars, or preheated
and packed hot. Raw or cold pack
means that raw, unheated food is
placed in jars and covered with boiling
hot sirup, juice, or water. When
foods are hot packed they are heated
in sirup, water or steam, or juice for
a specified length of time and then
packed hot into jars.
Most raw fruits and vegetables can
be packed fairly tightly into containers
because they cook down during
processing. However, raw corn,
lima beans, and peas should be
packed loosely because they expand
during processing.
Hot food should be packed fairly
loosely. It should be at or near the
boiling temperature when packed.
There should be enough sirup, water,
or juice to fill in around the solid
food in the container and to cover
the food. Food at the top of the container
may darken if not covered with
liquid.
Do not overpack containers as this
may result in underprocessing. It is
necessary to leave headspace between
the lid and the top of the food
or liquid in the jar because there will
be some expansion of food during
processing. The amount of headspace
varies with the product, style of pack,
and method of heat sterilization, so
follow directions for each fruit or
vegetable.
When using the flat metal lid with
sealing compound, put the lid on a
clean jar rim, with sealing compound
next to the glass. Then screw the
metal band down firmly. The lid will
still have enough “give” to let steam
escape during processing. Do not
tighten the band further after removing
the jar from the canner.
When using the porcelain-lined
zinc cap, fit the wet rubber ring down
on the jar shoulder. Fill the jar and
wipe clean the rubber ring and jar
rim. Screw the cap down firmly and
turn back ¼ inch. When the jar is
removed from the canner, tighten the
cap to complete the seal.
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Sugar or sugar-water sirup is often
added to fruits to help them hold
their shape, color, and flavor. Sugar
can be added in the dry form to very
juicy fruits.
To make sugar sirup—mix sugar
with water or juice extracted from
the fruit. Proportions for 3 types of
sirup are as follows:
Type of Sirup
Sugar (cups)
Liquid (cups)
Thin
2
4
Medium
3
4
Heavy
4¾
4
Heat sugar and water or juice together
until sugar is dissolved.
Fruit may be canned without sweetening—in
its own juice or in water—for
special diets. Processing time is
the same for unsweetened fruit as
for sweetened because sugar is not
needed to prevent spoilage.
Process fruits by the boiling-water-bath
method. Work only with the
quantity of food needed for one canner
load at one time.
As each jar is filled, adjust the lid,
and place the jar on the rack in the
water-bath canner about one-half full
of hot or boiling water for raw or hot
pack, respectively. Be sure the water
is 1 to 2 inches over the tops of the
jars, and there is an additional 1- to
2-inch space to allow the water to
boil freely.
Cover the canner and when the
water comes to a rolling boil, start
to count the processing time. Boil
gently and steadily for the recommended
time for the fruit you are
canning. A definite length of time is
recommended for processing each
kind of fruit.
When the processing time is completed,
immediately remove the jars
from the canner with a pair of jar
tongs. Adjust the jar lids if necessary.
Cool the jars on a rack or folded
towel away from drafts.
Hot packing peaches.
Covering
peaches with a boiling sirup solution.
A steam-pressure canner must be
used for processing all vegetables except
tomatoes and pickled vegetables.
Work only with the quantity of vegetable
needed for one canner load at a
time. As each jar is filled, adjust the
lid, and place the jar in the pressure
canner containing 2 to 3 inches of hot
or boiling water for raw or hot pack,
respectively, to keep food hot.
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The manufacturer’s directions for
general operation of the canner you
are using should be followed. A few
pointers on the use of any canner
follow:
—Use 2 to 3 inches of boiling water
in the bottom of the canner.
—Set filled containers on rack in
canner.
—Fasten canner cover securely.
—Allow steam to escape from
open petcock or weighted gage opening
for at least 10 minutes to drive
all air from canner. Then close petcock
or put on weighted gage.
—When pressure reaches 10
pounds (240° F), start counting processing
time. Keep pressure constant
by regulating heat under the canner.
—When processing time is completed,
remove the canner from heat
immediately. Cool undisturbed at
room temperature until the pressure
registers zero. After a minute or two,
slowly open the petcock or remove
the weighted gage. Unfasten the cover
and tilt the far side up so steam
escapes away from you.
—Remove containers from canner
with jar tongs.
—Adjust lids if necessary.
—Cool jars on a rack or folded
towel away from drafts.
Cooling snap beans on a rack. Leave
space between jars so air can circulate.
Jars should be examined after they
have cooled, but within 24 hours
after processing, to be sure a seal has
been obtained. To test a jar that has
a flat metal lid, press the center of
the lid; if the lid is down and will
not move, it is sealed. Turn jars with
porcelain-lined zinc caps partly over
in your hands; if they do not leak,
they are sealed.
When jars are thoroughly cooled,
metal screw bands should be carefully
removed. Wipe outside of jars
clean, and label jars to show date and
contents. Store in cool dry place. If
you find a jar that did not seal, use
food right away or re-can the food
immediately; empty the jar, pack and
process the food as if it were fresh.
Check dates on jar labels to be sure
you first use food that has the earliest
processing date. Before opening any
jar for use, look at it carefully for
spoilage signs. If it leaks, has a bulging
lid, spurts liquid when opened,
or has an off-odor or mold, then do
not use it. Do not even taste it. Destroy
it out of the reach of children
and pets.
Canned vegetables may contain the
toxin that causes botulism without
showing any visible signs of spoilage.
Therefore, boil all home-canned vegetables
covered for at least 10 minutes
before tasting or serving. Heating
generally makes any odor of spoilage
more evident.
If the food appears to be spoiled,
foams, or has an off-odor during
heating, destroy it.
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1. Select green beans:
Choose young, tender beans
Allow 1½ to 2½ pounds of fresh beans for each quart to be canned
2. Prepare green beans:
Wash beans
Trim ends
Cut into 1-inch pieces
3. Pack into jars:
To pack raw—
Pack raw beans tightly into jar
Leave ½-inch space at top of jar
Add ½ teaspoon salt to pints; 1 teaspoon to quarts
Cover with boiling water to ½ inch from top of jar
Wipe jar rim clean
Adjust jar lid
Process in pressure canner at 10 pounds pressure (240° F)
Pints—20 minutes
Quarts—25 minutes
(At altitudes above sea level, increase pressure according to instructions in early part of chapter)
To pack hot—
Cover cut beans with boiling water; boil 5 minutes
Pack hot beans loosely into jar to ½ inch of top
Leave ½-inch space at top of jar
Add ½ teaspoon salt to pints; 1 teaspoon to quarts
Cover with boiling water to ½ inch from top of jar
Wipe jar rim clean
Adjust jar lid
Process in pressure canner at 10 pounds pressure (240° F)
Pints—20 minutes
Quarts—25 minutes
(At altitudes above sea level, increase pressure according to instructions given earlier)
4. Allow pressure to return to 0
5. Remove jars from canner
6. Complete seals, if necessary
1. Select peaches:
Choose fresh, firm, ripe fruit, with no soft spots or bruises
Allow 2 to 3 pounds of fresh peaches for each quart to be canned
2. Prepare peaches:
Wash peaches
Dip in boiling water; then in cold water
Slip off skins
Cut in halves and remove pits. Slice if desired
3. Prevent darkening:
Drop peeled peaches into solution of 2 tablespoons each of salt and vinegar per gallon of water
(At altitudes above sea level, increase processing time according to table near start of chapter)
To pack hot—
Heat peaches through in hot sirup (See sirup table). If fruit is very juicy, heat it with sugar, adding no liquid
Pack hot fruit in jar to ½ inch of top
Cover with boiling sirup
Leave ½-inch space at top of jar
Wipe jar rim clean
Adjust jar lid
Process in boiling-water bath—
Pints—20 minutes
Quarts—25 minutes
(At altitudes above sea level, increase processing time according to table near start of chapter)
5. Remove jars from canner
6. Complete seals, if necessary
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Freezing Your Garden’s Harvest — Packaging Material — Selecting and Preparing — Freezing and Storing — Thawing — How to Freeze Strawberries [11] — How to Freeze Green Peas [12] — For Further Reading:
The growing season brings an abundance
of fruits and vegetables freshly
harvested from your garden. The unmatchable
sweetness of peas cooked
fresh from the pods, the tender-crisp
texture of fresh broccoli, the delectable
flavor of sweet juicy strawberries
are irresistible. It is always a
disappointment when the growing
season is over. You may have more
produce than you were able to use
within a short time, so why not savor
its just-picked freshness during the
autumn and winter months—freeze it!
Of all the methods of home food
preservation, freezing is one of the
simplest and least time-consuming.
The natural colors, fresh flavors, and
nutritive value of most fruits and
vegetables are maintained well by
freezing. However, to freeze foods
successfully—that is, to preserve
their quality—produce must be carefully
selected, prepared and packaged,
and properly frozen. Be sure
to use reliable home-freezing directions
such as those found in U.S.
Department of Agriculture publications.
Unless recommended practices
and procedures are observed, the
food’s eating quality will be a disappointment.
The first consideration before deciding
whether to freeze the garden’s
harvest is whether your freezer can
maintain temperatures low enough to
preserve quality of the food during
freezer storage. Storage temperatures
must be 0° F (-18° C) or below to
help prevent unfavorable changes in
the food, including growth of bacteria.
The temperature control of your
freezer should be adjusted so the
warmest spot in the freezer will always
be at 0° F or lower. Freezers
and most two-door refrigerator-freezer
combinations are best suited
for long storage of home-frozen
fruits and vegetables since they can
be set to maintain this temperature.
Proper preparation of produce is
also important to insure high eating
quality of frozen vegetables and
fruits. Vegetables, except green peppers
and mature onions, maintain
better quality during freezer storage
if blanched, or heated briefly, before
freezing.
Blanching is necessary to prevent
development of off-flavors, discoloration,
and toughness in frozen vegetables.
Besides stopping or slowing
down the action of enzymes responsible
for these undesirable changes,
blanching also softens the vegetable,
making it easier to pack into containers
for freezing.
Fruit does not need to be blanched
before freezing. However, most fruits
require packing in sugar or sirup to
prevent undesirable flavor and texture
changes in the frozen product.
Sugar, either alone or as part of the
sirup, plus the acidity of fruit retards
enzyme activity in fruit stored
at 0° F or below.
Material selected for packaging
fruits and vegetables for freezing
must be moisture-vapor-proof or
moisture-vapor-resistant to keep the
food from drying out and from absorbing
odors from other foods in the
freezer. Loss of moisture from the
food causes small white areas called
“freezer burn” to develop. These
areas are not harmful, but if extensive
they can cause the food to become
tough and lose flavor.
Suitable packaging materials include
rigid plastic food containers,
335
plastic freezer bags, heavy aluminum
foil, freezer paper or plastic film,
glass freezer jars, and waxed freezer
cartons. Collapsible, cardboard
freezer boxes are frequently used as
an outer covering for plastic bags to
protect them against tearing.
Select packaging materials suiting
the shape, size, and consistency of
the food. Rigid containers are suited
for freezing all foods, but are especially
good for fruit packed in liquid.
Non-rigid containers are best for
fruits and vegetables packed without
liquid. Paper, plastic, or foil wraps
are ideal for freezing bulky vegetables
such as broccoli, corn on the
cob, and asparagus.
Rigid containers with straight sides
and flat bottoms and tops stack well
in the freezer. They take up less
freezer space than rounded containers,
containers with flared sides, and
bulky, wrapped packages or plastic
bags without protective outer cartons.
Containers with straight sides
or those that are flared, having wider
tops than bottoms, are preferred for
easy removal of the food before
thawing. If the opening is narrower
than the body of the container, the
food will have to be partially thawed
so you can get it out of the container.
Freezer containers and bags are
available in a variety of sizes. Do
not use those with more than ½-gallon
capacity for freezing fruits and
vegetables since the food will freeze
too slowly, causing poor quality food.
Choose a container that will hold
enough food for one meal for your
family. You may wish to put up a few
smaller packages for use when some
family members are not home or to
go with your family-size packages
when guests are present for meals.
Pack foods tightly into containers.
Since most foods expand during freezing,
leave headspace between the
packed food and closure.
For fruits that are in liquid, pureed,
or crushed and packed in containers
with wide openings, leave ½-inch
headspace for pints, 1-inch headspace
for quarts. If containers with
narrow openings are used, leave ¾-inch
headspace for pints, 1½-inch
headspace for quarts.
For fruits and vegetables packed
without liquid, leave ½-inch headspace
for all types of containers.
Vegetables that pack loosely, such as
asparagus and broccoli, require no
headspace.
Any container for freezer use must
be capable of a tight seal. Rigid containers
should have an airtight-fitting
lid.
Press out all air from the unfilled
parts of plastic bags. Immediately
twist the top of each bag and securely
tie it with a paper- or plastic-covered
wire twist strip, rubber band,
or string to prevent return of air to
the bag.
Some bags may be heat-sealed with
special equipment available on the
market. Follow the manufacturer’s
directions.
Edges and ends of paper, foil, or
plastic wraps should be folded over
several times so the wrap lies directly
on top of the food and all air has
been pressed out of the package.
Seal the ends with freezer tape to
hold them securely in place.
Grow varieties of fruits and vegetables
that freeze well. Your county
Extension office can provide information
on suitable varieties that grow
well in your locality.
Produce selected for freezing should
be of optimum eating quality. Freezing
only preserves the quality of produce
as it is at the time of freezing.
It never improves quality.
Fruits to be frozen should be firm
and ripe. Underripe fruit may have a
bitter or off-flavor after freezing.
Pick berries when ripe and freeze
them as soon after picking as you
336
can. Some fruits—apples, peaches,
pears—may need to ripen further
after harvesting. But take care they
don’t get too ripe. Frozen fruit prepared
from overripe fruit will lack
flavor and have a mushy texture.
Choose young, tender vegetables
for freezing. Since vegetables lose
quality quickly after harvest, freeze
them as soon as possible for maximum
quality. The sugar in corn, peas, and
lima beans is rapidly lost when held
too long before freezing. If you must
hold vegetables and ripe fruits for a
short while, refrigeration will help
retain the just-picked freshness better
than leaving produce at room temperature.
Wash small quantities of fruit
gently in cold water. Do not permit
fruit to stand in water for any length
of time since it will become water-soaked
and lose flavor and food
value. Drain fruit thoroughly.
Peel fruit and remove pits or seeds.
Halve, slice, chop, crush, or puree
fruit as indicated in the instructions
for each specific fruit. Some fruit,
especially berries, may be left whole,
but remove stems or hulls. Work
with small quantities of fruit at a
time, particularly if it is fruit that
darkens rapidly. Two to three quarts
is an adequate amount to handle at
one time.
Pack fruit by sirup pack, sugar
pack, or unsweetened pack. Most fruit
has better texture and flavor with a
sweetened pack. Apples, avocados,
berries, grapes, peaches, persimmons,
and plums can all be frozen satisfactorily
without sweetening, but the
quality is not quite as good as freezing
in sirup or sugar. An unsweetened
pack will give as good a quality product
for gooseberries, currants, cranberries,
rhubarb, and figs as a sweetened
pack.
Sirup pack. Make a sugar sirup by
dissolving sugar in water. A 40%
sirup (3 cups of sugar to 4 cups of
water) is recommended for freezing
most fruits. Sirups containing less
sugar are sometimes used for mild-flavored
fruits; those with more sugar
for very sour fruits. The type of
sirup to use is specified in the directions
for freezing each fruit. Allow
½ to ⅔ cup of sirup for each pint
of fruit. Cut fruit directly into the
freezer container, leaving the recommended
headspace. Add sirup to
cover fruit.
Slicing strawberries before freezing in
a sugar pack.
Sugar pack. Cut fruit into a large
bowl. Sprinkle with sugar. The
amount of sugar to use is specified
in freezing directions for each fruit.
Mix gently until juice is drawn from
the fruit and all the sugar is dissolved.
Pack fruit and juice into
freezer containers.
Unsweetened pack. Some fruit may
be packed dry, without added liquid
or sugar. Other fruit, particularly if
it darkens rapidly, can be covered
with water to which ascorbic acid has
been added. Crushed fruit or sliced
fruit that is very juicy can be packed
in its own juice without added liquid.
For all packs except the dry, unsweetened
pack, liquid—either sirup,
juice, or water—should completely
cover the fruit. This prevents the top
pieces from changing color or losing
flavor due to exposure to air in the
headspace.
A small crumpled piece of waxed
or parchment paper placed on top of
the fruit helps keep it pressed down
337
in the liquid once the container has
been sealed. The paper should loosely
fill the headspace area. Do not use
aluminum foil since acid in the fruit
can cause the foil to pit (form holes),
and tiny pieces of foil may drop into
the food.
Anti-darkening. Many fruits darken
during freezing, particularly if not
kept under liquid. Darkening occurs
when the fruit is exposed to air.
Since a small amount of air is in the
liquid as well as the tissues of fruit,
some darkening can occur even when
the fruit is submerged in liquid. To
help retard darkening during freezer
storage, add ascorbic acid (vitamin C)
to the fruit during preparation.
Ascorbic acid is available in several
forms from drug stores, some freezer
locker plants, and some grocery
stores that sell freezing supplies.
Crystalline ascorbic acid is easier to
dissolve in liquid than powder or
tablet forms. The amount of ascorbic
acid to use is given in the directions
for those fruits where use of ascorbic
acid is beneficial. Ascorbic acid mixtures
containing sugar, and sometimes
citric acid, also are available. Follow
the manufacturer’s directions for use
of these products.
In preparing vegetables, wash a
small quantity of the vegetable gently
in several changes of cold water. Lift
the vegetable out of the water each
time so all dirt will settle to the bottom
of the sink or pan.
Shell, husk, or peel and trim. Some
vegetables such as lima beans, corn
on the cob, and asparagus require
sorting for size, since blanching times
depend on size of the pieces.
Blanch the vegetable (this is not
necessary for green peppers and mature
onions). Most vegetables are
blanched by heating them in boiling
water. A blancher consisting of a tall
kettle, basket, and cover is convenient
to use and can be purchased
at most department or farm supply
stores. However, any large pan which
can be fitted with a wire or perforated
metal basket and covered is
suitable.
To insure adequate blanching, immerse
a basket containing a small
amount of the vegetable (1 pound)
into a large amount of boiling water
(at least 1 gallon). Start timing once
the vegetable has been immersed and
the kettle is covered. Blanching time
will vary with the vegetable and the
size of the pieces, so follow the recommended
blanching times for each
vegetable.
Cool the vegetable by immersion
in a large quantity of cold or iced
water. Rapid cooling is necessary to
stop the food from cooking. Cool the
vegetable for about the same length
of time as it was heated. Once cooled,
do not leave the vegetable standing
in water, as loss of flavor and food
value can occur. Drain the cooled
vegetable thoroughly before packaging.
Other methods of blanching and
cooling are recommended for some
vegetables. For example, mushrooms
are heated by sauteing, tomatoes by
simmering in their own juice. These
foods are cooled by setting the pan
of food in cold or iced water to speed
cooling.
After packing and sealing containers,
label them with the name of the
food, type of pack (for fruits), and
date of freezing. Freeze food soon
after packing, placing a few packages
at a time in the freezer as you have
them ready.
Freeze food at 0°F or below. Do
not load the freezer with more food
than can be frozen in 24 hours. Usually
2 to 3 pounds of food per cubic foot
of freezer capacity can be frozen at
a time. Place packages on freezing
coils or plates or in fast-freeze section
of freezer, leaving a space between
each package. Loading the
freezer in this manner enables the
338
food to be frozen quickly. Freezing
foods too slowly can result in loss of
quality.
Once food has frozen, stack containers.
Keep freezer surfaces relatively
free from frost to insure maximum
operating efficiency of your
freezer.
Fruits and vegetables stored at 0°
F or below will maintain high quality
for 8 to 12 months. Unsweetened
fruit loses quality more rapidly than
sweetened fruit.
Keeping food longer than the
recommended time will not make it
unsafe to eat, but some quality loss
can occur.
Home-frozen fruits and vegetables
are convenient and easy to use since
most of their preparation is done before
freezing. Thaw frozen fruit in
the refrigerator, or at room temperature
in a pan of cool water. Leave
fruit in the unopened freezer container.
A pint package of fruit frozen in
sirup will take about 6 to 8 hours to
thaw in the refrigerator, or ½ to 1
hour in a pan of cool water. Fruit in
sugar packs takes less time. Unsweetened
packs need more time than
sirup packs. For best eating quality,
serve fruit with a few ice crystals
remaining.
Cook most frozen vegetables without
thawing first. (Corn on the cob
and leafy vegetables require partial
thawing to insure even cooking.) Add
the vegetable to boiling salted water.
Use 1 cup of water and 1 teaspoon
of salt for each quart of vegetable
with these exceptions: Use 2 cups of
water for lima beans; water-to-cover
for corn on the cob. Cover the saucepan
during cooking. Cook the vegetable
only until tender. Avoid overcooking.
Consult timetable in freezing directions
for recommended times for
cooking home-frozen vegetables.
1. Select strawberries:
Choose firm, ripe red berries with a slightly tart flavor
Allow about 1½ quarts fresh strawberries for each quart to be frozen
2. Prepare strawberries:
Wash berries in cold water; drain well
Remove hulls
3. Pack into rigid freezer containers:
To pack in sirup—
Prepare ahead of time a 50 percent sirup by dissolving 4¾ cups sugar in 4 cups of water; this will make 6½ cups sirup
Add about ½ cup sirup to each container
Put berries into prepared containers
To pack in sugar—
Add ¾ cup sugar to each quart berries
Mix gently until sugar is dissolved and juice is drawn from berries
Pack strawberries with juice in containers
To pack unsweetened—
Put berries into containers
For better color, cover with cold water containing 1 teaspoon ascorbic acid per quart of water
For all packs—
Press fruit gently down in each container; add liquid (sirup, juice, or water) to cover fruit, unless fruit is packed dry, unsweetened
Put a small piece of crumpled waxed paper on top of berries to keep them down in liquid
Wipe all liquid from top and sides of containers
Seal tightly with lid
Label with name of fruit, type of pack, and date of freezing
4. Freeze strawberries:
Immediately after packaging, place berries in freezer set at 0° F or below; leave space around each container for faster freezing
Do not freeze more than 1 quart of berries per cubic foot of freezer capacity at a time
Stack containers of berries once frozen; store at 0° or below
339
1. Select green peas:
Choose bright-green, plump, firm pods with sweet, tender peas (do not use immature or tough peas)
Allow 4 to 5 pounds fresh peas for each quart to be frozen
2. Prepare green peas:
Shell peas
Wash shelled peas in cold water; drain
3. Blanch green peas:
Bring 1 gallon water to a boil in a large kettle
Put peas (1 pound) in blanching basket
Lower basket into boiling water
Cover kettle and heat peas 1½ minutes
Chill peas promptly in cold or iced water 1½ minutes
Drain cooled peas
4. Pack green peas:
Pack drained, blanched peas in freezer containers (See reference on containers in early part of chapter)
Leave ½-inch headspace between peas and closure
Seal containers tightly
Label each package with name of vegetable and date
5. Freeze green peas:
Immediately after packaging, place peas in freezer set at 0° F or below; leave space around each container for faster freezing
Do not freeze more than 2 to 3 quarts of peas per cubic foot of freezer capacity at a time
Stack packages of peas once frozen; store at 0° F or below
Home Freezing of Fruits and Vegetables,
U.S. Department of Agriculture H&G
Bul. No. 10, on sale by Superintendent
of Documents, U.S. Government Printing
Office, Washington, D.C. 20402.
75¢.
340
Jellies, Jams, Marmalades, Preserves — Jam and Jelly Equipment — Extraction — When It’s Done — If It Doesn’t Gel — How to Prevent Problems With Jellied Products — For Further Reading:
Changing fruit into a variety of
products such as jellies, jams, marmalades,
and preserves can be most
rewarding. These products serve as
a good way to use fruit that is not
completely suitable for canning or
freezing, while adding variety and
economy to the home food preservation
plan.
Jams, jellies, and preserves are similar
in that they are preserved using
sugar, and all are jellied or partially
jellied. Each differs from the other
due to the fruit used, ratio of ingredients,
and methods of preparation.
Jelly is made using fruit juice. It
is clear and firm enough to hold its
shape when removed from the jar.
Jam is made from crushed or
macerated fruit. Less firm than jelly,
it spreads more easily.
Conserves are jams made from a
mixture of fruits including citrus.
Sometimes nuts and raisins are added.
Preserves are whole fruits or large
pieces of fruit in a sirup that varies
in thickness.
Marmalades are usually made from
pulpy fruits, with skin and pulp suspended
in a clear, jellied liquid. For
citrus marmalades, the peel is sliced
very thin.
Butters are made by cooking fruit
pulp with sugar to a thick consistency
which spreads easily.
Jellied fruit products need a balanced
ratio of fruit, acid, pectin, and
sugar for best results.
Fruit provides the characteristic
color and flavor, and furnishes at
least part of the pectin and acid that
combines with added sugar to give
the desired gel. Full flavored fruits
are needed to offset the dilution of
flavor by the large proportion of sugar
used.
Pectin is the actual jellifying substance
and is found in many fruits in
adequate quantity. If pectin is lacking,
apple juice extract or commercial pectin
may be used. All fruits have more
pectin when underripe.
Commercial pectin is available in
both liquid and powder forms. It is
essential to follow the manufacturer’s
instructions or tested recipes as in
U.S. Department of Agriculture publications.
These preparations generally
bring higher yields plus the advantages
of being able to use fully
ripe fruit, with a shorter cook time
and more uniform results.
Acid content varies among fruits
and is higher in underripe fruits. Acid
is needed both for gel formation and
for flavor. When fruits are low in
acid, lemon juice or citric acid may be
used. Commercial pectins also have
added acid.
Either beet or cane sugar in fruit
products acts as a preserving agent,
helps in forming the gel, and enhances
the finished product’s flavor. In preserves,
sugar aids in firming the fruit
or fruit pieces.
Sweeteners such as brown sugar,
sorghum and molasses are not recommended
since their flavor overpowers
the fruit flavor and their sweetness
varies.
Other than artificial sweeteners,
suitable sugar replacements are light
corn sirup and light, mild honey. Neither
can substitute fully for sugar on
a one-to-one basis. For best results
use a tested recipe, but if one is not
available replace about ¼ to ½ of
the sugar with corn sirup or honey.
Longer boiling (for recipes without
341
pectin) may be required since additional
moisture is being added.
Fruits for jellied products without
added pectin must be hard ripe and
full flavored, or in a proportion of ¾
fully ripe and ¼ underripe, in order to
provide the needed pectin. If liquid or
powdered pectin is used, fully ripe
fruit is best.
After sorting to remove overripe or
undesirable fruit, wash in cold running
water or several changes of cold
water. Prepare fruit according to the
specific recipe, discarding any spoiled
or bruised portions. Only the amount
needed should be prepared to prevent
quality loss.
Water bath canner
Jelly thermometer
Timer
Widemouth funnel
Large, flat-bottomed kettle (8-10 qt.)
Measures
Measuring cup and spoons
Food chopper or masher
Long-handled spoon
Colander
Ladle
Jar lifter
Jelly bag and cheesecloth
Jelmeter
Canning jars and fittings
In jelly making, juice is extracted
either by crushing, by limited heating
using small amounts of water, or
by longer cooking with measured
amounts of water. Heating aids in pectin
extraction for those recipes not
using added pectin.
The prepared fruit is put in a damp
jelly bag or several thicknesses of
damp cheesecloth, tied, and hung to
drip. The clearest juice will be free
run, but yields increase if the bag is
pressed or twisted. Re-straining this
juice is recommended. Do not squeeze
or press.
Jams, jellies, and preserves can be
made with added pectin or without
it, depending on the fruit. Fruits such
as raspberries, strawberries, and
peaches generally need added pectin.
Apples, crabapples, currants, plums,
grapes, and quinces—if not overripe—contain
enough pectin and acid for
good gel strength.
Pectin content can be checked visually
by mixing 1 tablespoon of cool
cooked fruit juice and 1 tablespoon of
denatured alcohol and mixing. Fruit
high in pectin will form a jellylike
mass while fruit low in pectin will
show little clumping. Caution: Do not
taste; the mixture is poisonous.
Pectin may also be tested using a
jelmeter. This graduated glass tube
measures the rate of fruit juice flow
through the tube, giving a rough estimate
of the amount of pectin present.
Jellied fruit products made without
added pectin require less sugar per
fruit unit and need longer boiling to
reach the end point. The yield of finished
product is less than that with
added pectin.
Pectin added to fruit, either in powder
or liquid form, must be used in
recipes designating the type. Powdered
pectin is mixed with the unheated
fruit juice or unheated crushed
fruit.
Liquid pectin is added to the boiling
fruit juice or fruit and sugar mixture.
The boiling time of 1 minute for both
types is used and must be accurately
timed. Regardless of type, or whether
pectin is used, you must follow directions
closely, taking accurate
measurements.
One of the largest concerns when
making jelly without added pectin is
to know when it is done, or judging
the end point. Two of the most frequently
used methods for testing
doneness of jelly without added pectin
are the temperature test and the
spoon or sheet test.
342
The temperature test is the most
scientific method and probably the
most dependable. Before cooking
jelly, take the temperature of boiling
water with a jelly or candy thermometer.
Cook the jelly mixture to a
temperature 8° F higher than the boiling
point of water. If cooked to this
point, the jelly mixture should form
a satisfactory gel. Cook other jellied
mixtures to a temperature 9° higher
than the boiling point of water.
To get an accurate reading, place
the thermometer in a vertical position
with the bulb completely covered
by the jelly mixture but not touching
the bottom of the kettle. Stir jam,
preserve, conserve, and marmalade
mixtures before taking the temperature.
Read the thermometer at eye
level.
To test the jellying point by the
spoon or sheet test, dip a cool metal
spoon into the boiling jelly mixture
and lift the spoon so the sirup runs
off the side. When the sirup no longer
runs off the spoon in a steady stream,
but two drops form together and
sheet off the spoon, the jelly should
be done.
Pouring hot jelly mixture into canning
jars.
Once the jellying point is reached,
quickly pour jelly into sterilized containers.
When sealing jelly with lids,
use only standard canning jars and
new lids. Pour the boiling hot jelly
mixture into sterilized hot jars, leaving
⅛ inch head space. Wipe the jar
rims clean, place hot metal lids on
jars with the sealing compound next
to the glass, screw the metal bands
down firmly, and stand the jars upright
to cool.
The paraffin seal is recommended
only for jelly. Pour the boiling hot
jelly mixture into sterilized hot containers,
leaving ½ inch head space.
Cover hot jelly with hot paraffin to
make a single thin layer ⅛ inch thick.
Paraffin should touch all sides of the
container. Prick air bubbles in the
paraffin.
Heat processing of jams, preserves,
conserves, and marmalades is recommended,
especially in warm or humid
climates. Place filled jars on a rack
in a water bath canner or other large
container filled with hot water. The
water should be an inch or two over
the tops of the jars. Cover canner.
Bring the water to a rolling boil and
boil gently for five minutes.
Remove the products from the canner
immediately when the processing
time is up. Place the containers on a
rack or folded cloth away from drafts
to cool.
Let jellied products stand overnight
to avoid breaking the gel. Remove
screw bands, and label the containers
with the name of the product and the
date. Store in a cool, dry place. Jellied
products have a much better flavor
and color if stored only for a short
time.
What if the jelly doesn’t gel? Try
using it as a topping for pancakes or
ice cream, or try recooking the mixture.
To remake jelly without added
pectin, heat the jelly to boiling and
boil for a few minutes until the jellying
point is reached. Remove the jelly
from the heat, skim, pour into hot,
sterilized containers and seal.
343
Problem
Cause
Prevention
Formation of crystals
Excess sugar
Test fruit juice with jelmeter for proper proportions of sugar
Undissolved sugar sticking to sides of kettle
Wipe side of pan free of crystals with damp cloth before filling jars
Tartrate crystals in grape juice
Make grape jelly stock, and let tartrate crystals settle out before making jelly. Then strain through two thicknesses of cheesecloth to remove crystals
Mixture cooked too slowly or too long
Cook at a rapid boil. Remove from heat immediately when jellying point is reached
Syneresis or “weeping”
Excess acid in juice makes pectin unstable
Maintain proper acidity of juice
Storage place too warm or storage temperature fluctuated
Store in a cool, dark and dry place
Paraffin seal too thick
Seal jelly with a single thin layer of paraffin ⅛ inch thick. Prick air bubbles in paraffin
Too soft
Overcooking fruit to extract juice
Avoid overcooking as this lowers the jellying capacity of pectin
Incorrect proportions of sugar and juice
Follow recommended instructions
Undercooking causing insufficient concentration
Cook rapidly to jellying point
Insufficient acid
Avoid using fruit that is overripe. Lemon juice is sometimes added if fruit is acid deficient
Making too large a batch at one time
Use only 4 to 6 cups of juice in each batch of jelly
Too stiff or tough
Overcooking
Cook jelly mixture to a temperature 8° F higher than the boiling point of water or until it “sheets” from a spoon
Too much pectin in fruit
Use ripe fruit
Cloudy
Green fruit (starch)
Use firm, ripe fruits or slightly underripe
Imperfect straining
Do not squeeze juice but let it drip through jelly bag
Jelly allowed to stand before it was poured into jars or poured too slowly
Pour into jars immediately upon reaching jellying point. Work quickly
Bubbles
Kettle was not held close to top of jar as jelly was poured, or jelly was poured slowly and air became trapped in hot jelly
Hold kettle close to top of jar and pour jelly quickly into jar
May denote spoilage.
Follow recommended methods to get airtight seal
If bubbles are moving, do not use
Mold (denotes spoilage; do not use)
Imperfect seal
Use recommended methods to get airtight seal
Lack of proper sanitation
Sterilize jelly glasses and all equipment used
344
To remake with powdered pectin,
measure ¼ cup sugar, ¼ cup water,
and 4 teaspoons powdered pectin for
each quart of jelly. Mix the pectin
and water and bring to a boil, stirring
constantly. Add the jelly and the
sugar, stir thoroughly, and bring to a
full rolling boil over high heat, stirring
constantly. Boil the mixture hard
for 30 seconds, remove from the heat,
pour into hot containers and seal.
To remake with liquid pectin, measure
¾ cup sugar, 2 tablespoons
lemon juice, and 2 tablespoons liquid
pectin for each quart of jelly. Bring
the jelly to a boil over high heat. Add
the sugar, lemon juice and liquid pectin
and bring to a rolling boil, stirring
constantly. Boil the mixture hard for
1 minute. Remove the jelly from the
heat, skim, pour into hot, sterilized
containers and seal.
High quality jellied products depend
on many factors so there may
be several possible solutions to problems
in making these products. Some
common problems and their prevention
are given in the table.
How To Make Jellies, Jams and Preserve
at Home, H&G Bul No. 56, on sale by
Superintendent of Documents, U.S.
Government Printing Office, Washington,
D.C. 20402. 55¢.
345
Pickles, Relishes Add Zip and Zest — Ingredients — Equipment — Heat Treatment — Pickle Problems — For Further Reading:
Pickles or relishes can add zip and
zest to your meals, snacks and party
refreshments. They contain small
amounts of nutrients, depending on
ingredients used in making them.
But they have little or no fat and are
low in calories, except for the sweet
varieties.
Sun-drying, salting, smoking and
pickling were methods used in ancient
times for preserving food. Pickling
is still popular today.
Pickling is preserving foods in
vinegar or brine or a combination of
the two. Other ingredients are sometimes
added to make pickles crisp and
spicy.
Relishes and some pickles can be
made in a few hours. Other pickles
may take three to six weeks.
There are four basic classifications
of pickle products, depending on ingredients
used and method of preparation.
Brined pickles are sometimes called
fermented pickles and take three
weeks or longer to cure. Dilled cucumbers,
sauerkraut and some vegetables
are often prepared this way.
Cucumbers change from a bright
green to an olive or yellow green
while the interior becomes uniformly
translucent. Sauerkraut is tart and
tangy in flavor, creamy-white in
color, and crisp and firm.
Fresh pack pickles are also called
the quick process. This method is
very popular for the family with
limited time. Ingredients are combined
and put directly in the jar to be heat
processed, or combined and heated
a short time before being placed in
the jar for heat processing.
Fruit pickles are usually made of
whole fruits simmered in a spicy,
sweet-sour sirup. Some of the favorites
are peach, pear and watermelon
rind.
Relishes are made from chopped
fruits or vegetables (or a combination),
with seasonings added and
cooked to a desired consistency. They
can be hot, spicy, sweet or sour, depending
on the recipe used. Corn
relish, chili sauce, catsup, chow-chow
and chutney are popular examples.
Always use a tested recipe; one
that is current and reliable. Too little
of one ingredient and too much of
another could cause the pickles to be
unsafe to eat. Read the complete recipe
before starting the preparation,
and be sure you understand exactly
what you are to do. Check to see you
have all the ingredients. Accurate
measurements and weights are most
important in making pickles and
relishes if a quality and safe product
is to be the result.
Use only good quality fruits and
vegetables. Select tender vegetables
and firm ripe fruit. Pears and peaches
may be slightly underripe for pickling.
The pickling type cucumber is the
variety you will want to use. The
salad (slicing) variety does not make
a crisp pickle. Contact your county
Extension office for the variety grown
in your area.
Wax-coated cucumbers bought from
the vegetable counter are not suitable
for pickling because brine cannot
penetrate the wax. Besides, cucumbers
for pickling should be used
within 24 hours after gathering. If
they are kept—even refrigerated—longer
than 24 hours before the pickling
process begins, you may have a
poor quality product.
Always remove the blossom. This
may contain fungi or yeasts which
could cause enzymatic softening of
the cucumber. If whole cucumbers are
346
to be brined, you may want to leave
a ¼-inch stem.
Do not use vegetables or fruits
that have even a slight evidence of
mold or decay.
In preparing fruits and vegetables
to be pickled, wash them thoroughly
in cold water whether they are to be
peeled or not. Lift out of the water
each time, so soil that has been
washed off will not drain back over
them. Rinse the pan thoroughly between
each washing. This is a good
time to check again to see if you have
fruits or vegetables that should not
be used. Too, you can sort as to size,
shape and color. This makes for a
uniform pack and attractive product.
SALT—Pure granulated salt with
no noncaking material or iodine added
is best. This is sold as pickling salt,
“barrel” salt, and “kosher” salt. Pickling
salt is sold at the grocery store
and “barrel” salt from many farm
supply stores.
Table salt contains noncaking materials
that may interfere with fermentation
during brining. It also may
make the brine cloudy. Iodized salt
may darken pickles. Never use ice
cream salt or rock salt—they are not
food-pure.
VINEGAR—Use a 4 to 6 percent
acidity (40 to 60 grain) cider or white
vinegar. Read the label, for if it does
not have the amount of acidity listed,
it should not be used for making
pickles or relishes. Some vinegar has
19 percent acidity—this must be diluted.
Directions are on the label.
Don’t use homemade vinegar since
the acidity is not known.
Cider vinegar, used in most recipes,
has a good flavor and aroma but may
discolor pears, cauliflower, onions;
therefore white distilled vinegar is
used for these. If a less sour product
is preferred, choose a recipe that has
more sugar. Do not use less vinegar
than the recipe specifies.
SUGAR—Granulated, white sugar
is used in most pickles. However,
some recipes have brown sugar as an
ingredient and say so.
SPICES AND HERBS—Always use
fresh spices and herbs for best flavor.
They deteriorate and lose their pungency
in heat and humidity. If they
are not to be used immediately, store
them in an airtight container in a dark,
dry, cool place.
Whole spices, if left in the jar with
the pickles, will darken them; therefore
they can be tied in a thin cloth
bag and removed just before pickles
are packed into the jar. Ground spices
tend to darken pickles and relishes.
WATER—It is best not to use hard
water in brining. If you have hard
water, boil it in a stainless steel or
uncracked enamel container for 15
minutes. Remove from heat, cover,
and let sit for 24 hours. Remove any
scum which might have formed.
Slowly pour water from the container
so that sediment will not be disturbed.
The water is now ready to use.
Having the right kind, size and
amount of equipment and tools can
save you time and energy. Check
these the day before you plan to
make your pickles. Otherwise you
may not have what you need.
For fermenting or brining use a
crock or stone jar that has never had
fat or milk in it. An unchipped enamel-lined
pan, glass or stainless steel
are also O.K. Do not use plastic.
To cover vegetables while they are
in a brine, you will need a heavy
plate or large glass lid that fits inside
the container. Use a filled jar of water
to hold the cover down, so that vegetables
are kept below the surface of
the brine. Be sure the jar has a tight
fitting lid.
For heating pickling liquids, use
utensils of unchipped enamelware,
stainless steel, aluminum or glass. Do
not use copper, brass, galvanized or
347
iron utensils; these metals may react
with acids or salts and cause undesirable
color changes in pickles or
form undesirable compounds.
Among small utensils that will help
you do the job are measuring spoons,
stainless steel spoons, measuring cups,
household scales, sharp knives, vegetable
peelers, large trays, canning
tongs, ladle with a lip for pouring,
slotted metal spoons, footed colander
or wire basket, canning funnel, food
chopper or grinder, and non-porous
cutting board.
All pickles and relishes should be
processed in a boiling-water bath canner.
Any large metal or enamel container
may be used if it:
Is deep enough to allow 2 inches or more of water above the tops of the jars, plus extra space for boiling
Has a close-fitting cover
Is equipped with a wire or wooden rack
A steam-pressure canner can be
used if it is deep enough. For this
purpose, set the cover in place without
fastening it. Be sure the petcock
is wide open so that steam escapes
and pressure is not built up.
Standard home canning jars are
used for pickles and relishes. Do not
use jars and lids from commercially
canned foods. They are designed for
use on special packing machines and
are not suitable for home canning.
Select jars free from nicks, chips
or any defects. As you wash the jars
in warm soapy water and rinse them,
run your finger around the jar opening
to see if there is a defect. If there
is, the jar will not seal.
Look at each new metal lid to be
sure the sealing compound is even
and smooth. Check the metal screw
band to see that it is not bent or
rusty. Bands can be used over and
over again. As for pretreatment of
lids and bands, follow the manufacturer’s
directions. Read these even if
you have used that brand before; the
directions may have changed.
When using rubber rings get clean,
new ones that are the right size for
the jars. Do not test these by stretching.
Follow the manufacturer’s directions
as to pretreatment needed.
It is always best to follow current,
reliable procedures as in U.S. Department
of Agriculture or Extension publications.
This insures a quality product
and one that is safe to eat. Time,
energy and money may be wasted if
you use outdated or careless canning
procedures.
Fill the jars firmly and uniformly
with the pickle product. Avoid over-packing
so tightly that the brine or
sirup is prevented from filling around
and over the product. Slide a plastic
spatula down each side of the jar to
remove any air spaces. Add enough
liquid to cover the pickles. Be sure
to allow head space at the top of the
jar as recommended in the recipe.
This means there is no food or liquid
in that space.
Wipe the rim, inside and top, and
threads of the jar with a clean, damp
cloth to remove any particles of food,
spices, seeds or liquid. A small particle
may prevent an airtight seal.
The two-piece metal cap (flat metal
lid with sealing compound and metal
screw band) is the most commonly
used closure. Read the manufacturer’s
directions on treatment needed to
close the lid. These vary from one
manufacturer to another.
When using a porcelain-lined zinc
cap with shoulder rubber ring, screw
the cap down firmly against the wet
rubber ring, then turn it back one-fourth
inch. Immediately after processing
and removal of the jar from
the canner, screw the cap down tight
to complete the seal.
If liquid has boiled out of a jar
during processing, do not open it to
add more liquid, because spoilage
organisms may enter. This applies to
2-piece lids also. Seal the jar as it is.
348
All pickle products require heat
treatment to destroy organisms that
cause spoilage and to inactivate
enzymes that may affect flavor, color
and texture. Adequate heating is best
achieved by processing the filled jars
in a boiling-water bath.
Spoilage organisms are in the air
and there is danger of them contaminating
the food as it is transferred
from boiler to jar. This can
happen when even the utmost care
is taken. Therefore, boiling-water
bath processing is needed.
After adjusting the lid, put the jar
on the rack into the actively boiling
water.
Now that the jar is in the water
bath canner, fill the next jar. Continue
until all jars are in the canner. Be
sure to leave a small space around
each jar. This allows the water to
circulate. Water should come 2 or
more inches above jar tops; add boiling
water if necessary.
Cover the canner with a close-fitting
lid and bring the water back
to boiling as quickly as possible.
Start to count the processing time
when the water returns to boiling,
and continue to boil gently and
steadily for the recommended time
according to the recipe.
When time is up, slide the canner
from the hot range unit. Close windows
and doors so that a draft will
not be blowing on jars as they are
removed. As you remove the lid, be
sure to do this away from you so
that you will not be burned by steam.
Remove one jar at a time, using your
canning tongs. Complete the seals if
the manufacturer so directs. Set jars
upright, away from a draft, and several
inches apart, on a dry cloth or
wire rack to cool. Do not cover with
a cloth.
For fermented (brined) cucumbers
and fresh-pack dills, start to count
the processing time as soon as all the
filled jars are in the actively boiling
water. This prevents development of
a cooked flavor and loss of crispness.
Most pickle and relish recipe processing
times are given for altitudes
less than 1,000 feet above sea level.
If you are 1,000 feet or above, you
need to increase the recommended
processing time. See table in canning
chapter by Carole Davis.
After 12 to 24 hours, check to make
sure the jars have an airtight seal.
Read the manufacturer’s directions
but if these are not given, here are
some general ways to tell if the seal
is airtight. For the metal lid with a
sealing compound and the metal
screw band, if the center of the lid
has a slight dip or stays down when
pressed, the jar is sealed. Another
test is to tap the center of the lid
with a spoon. A clear, ringing sound
means a good seal. A dull note, however,
does not always mean a poor
seal. Another way to check for an
airtight seal is by turning the jar
partly over. If there is no leakage,
the jar may be stored.
If the porcelain-lined zinc cap with
rubber ring has been used, check for
airtight seal by turning the jar partly
over. If there is no leakage, the seal
is tight.
If the jar is not sealed, use the
product right away or recan it. To
recan, empty the jar, repack in another
clean jar, use a new lid, and
reprocess the product as before.
If metal bands are used, these can
be removed from jars after 24 hours
if you want to.
Wipe jars with a clean, damp cloth.
Make a label for the jar. Put the name
of the product and date on the label.
Store canned pickles and relishes
in a dark, dry, cool place where there
is no danger of freezing. Freezing
may crack the jars or break the seals,
and let in bacteria.
Before using, always examine each
jar for signs of spoilage. A bulging lid
or leakage may mean that the contents
are spoiled.
349
When a jar is opened look for other
signs of spoilage such as:
Spurting liquid
Mold
Disagreeable odor
Change in color
Unusual softness, mushiness or slipperiness
If there is ever the slightest indication
of spoilage, do not eat or even
taste the contents. Dispose of the contents
so they cannot be eaten by humans
or animals. Also dispose of the
lid.
After emptying the jar of spoiled
food, wash the jar in hot, soapy water
and rinse. Boil in clean water for 15
minutes.
Why are pickles soft or slippery?
This generally results from microbial
action which causes spoilage.
Once a pickle becomes soft it cannot
be made firm again. Microbial activity
may be caused by
—Too little salt or acid
—Cucumbers not covered with brine during fermentation
—Scum not removed from brine during fermentation
—Insufficient heat treatment
—Seal is not airtight
—Moldy garlic or spices
Blossoms, if not removed from the
cucumbers before fermentation, may
contain fungi or yeasts responsible
for enzymatic softening.
Why are pickles shriveled?
—Using too strong a vinegar, sugar or salt solution at the start of the pickling process. In making the very sweet or very sour pickles, it is best to start with a dilute solution and increase gradually to the desired strength
—Overcooking
—Overprocessing
Why are pickles dark?
—Use of ground spices
—Too much spice
—Whole spices left in jar
—Iodized salt
—Minerals in water, especially iron
—Overcooking
What causes garlic to turn purple or blue?
—Garlic contains anthocyanins, a water soluble pigment also found in beets. This changes color very easily and with the acid condition in pickles, turns blue or purple in color
How can you tell if sauerkraut is spoiled?
—Undesirable color
—Off odors
—Soft texture
Why does kraut get soft?
—Insufficient salt
—Too high temperatures during fermentation
—Uneven distribution of salt
—Air pockets caused by improper packing
Why does kraut get pink?
This is caused by growth of certain
types of yeast on the surface of the
kraut due to:
—Too much salt
—Uneven distribution of salt
—Kraut improperly covered or weighted during fermentation
Why does kraut turn dark?
—Unwashed and improperly trimmed cabbage
—Insufficient juice to cover fermenting cabbage
—Uneven distribution of salt
—Exposure to air
—Long storage period
—High temperature during fermentation, processing and storage
Making Pickles and Relishes at Home,
H&G Leaflet #92, on sale by Superintendent
of Documents, U.S. Government
Printing Office, Washington,
D.C. 20402. 45¢.
350
Wine Making (with a note on vinegar) — Making Red Wine — Sugar Correction Table — Clarifying — Making White Wine — Making Sweet Wine — Vinegar
Grapes are the world’s leading fruit
crop and the eighth most important
food crop in the world, exceeded only
by the principal cereals and starchy
tubers. Though substantial quantities
are used for fresh fruit, raisins, juice
and preserves, most of the world’s
annual production of about 60 million
metric tons is used for dry (non-sweet)
wine.
Wine is of great antiquity, as every
Bible reader knows, and a traditional
and important element in the daily
fare of millions. Used in moderation,
it is wholesome and nourishing, and
gives zest to the simplest diet. It is a
source of a broad range of essential
minerals, some vitamins, and easily
assimilated calories provided by its
moderate alcoholic content.
In its beginnings, winemaking was
as much a domestic art as breadmaking
and cheesemaking. It still is,
wherever grapes are grown in substantial
quantity. Though much wine
is now produced industrially, many
of the world’s most famous wines are
still made on what amounts to a
family scale, the grapegrower being
the winemaker as well.
Production of good dry table wine
for family use is not difficult, provided
certain essential rules are observed.
The right grapes. Quality of a wine
depends first of all on the grapes it is
made from. As is true of other fruits,
there are hundreds of grape varieties.
They fall in three main groups.
First, there are the classic vinifera
wine grapes of Europe. These also
dominate the vineyards of California,
with its essentially Mediterranean
climate. But several centuries of trial
have shown that they are not at home
in most other parts of the United
States.
Second, there are the traditional
American sorts such as Concord,
Catawba, Delaware, and Niagara,
which are descendants of our wild
grapes and much grown where the
vinifera fail. They have pronounced
aromas and flavors, often called foxy,
which, though relished in the fresh
state by many, reduce their value for
wine.
Third, there are the French or
French-American hybrids, introduced
in recent years and now superseding
the traditional American sorts for
winemaking. The object in breeding
these was to combine fruit resembling
the European wine grapes with vines
having the winter hardiness and disease
resistance of the American parent.
They may be grown for winemaking
where the pure European
wine grapes will not succeed.
What wine is. Simply described,
wine is the product of the fermentation
of sound, ripe grapes. If a quantity
of grapes is crushed into an open
half-barrel or other suitable vessel,
and covered, the phenomenon of fermentation
will be noticeable within a
day or two, depending on the ambient
temperature. It is initiated
by the yeasts naturally present on the
grapes, which begin to multiply prodigiously
once the grapes are crushed.
Fermentation continues for three to
ten days, throwing off gas and a
vinous odor. In the process, the sugar
of the grapes is reduced to approximately
half alcohol and half carbon
dioxide gas, which escapes. Fermentation
subsides when all the sugar
has been used up. The murky liquid
351
is then drained and pressed from the
solid matter and allowed to settle and
clear in a closed container.
The resulting liquid is wine—not
very good wine if the constituents of
the grapes were not in balance, and
readily spoiled, but wine nevertheless.
Beneath the apparent simplicity,
the evolution of grapes into wine is
a series of complex biochemical reactions.
Thus winemaking can be as
simple or as complex as you wish to
make it. The more you understand
and control the process, the better
the wine. The following instructions
cover only the essentials of sound
home winemaking.
Under Federal law the head of a
household may make up to 200 gallons
of wine a year for family use,
but is first required to notify the
Treasury Department’s Bureau of Alcohol,
Tobacco and Firearms on Form
1541.
The grape constituents which matter
most to the winemaker are (a)
sugar content of the juice, and (b)
tartness or “total acidity” of the juice.
Sugar content is important because
the amount of sugar determines alcoholic
content of the finished wine.
A sound table wine contains between
10% and 12½% alcohol. The working
rule is that 2% sugar yields 1% of
alcohol. Example: a sugar content of
22% yields a wine of approximately
11% alcohol.
California grapes normally contain
sufficient sugar. Grapes grown elsewhere
are often somewhat deficient,
and the difference must be made up
by adding the appropriate amount of
ordinary granulated sugar which
promptly converts to grape sugar on
contact with the juice.
What the saccharometer shows
For wine of 10% by volume, add
For wine of 12% by volume, add
Ounces of sugar per gallon
10
11.8
16.2
11
10.1
14.8
12
8.9
13.3
13
7.4
11.9
14
5.9
10.4
15
4.6
8.9
16
3.0
7.5
17
1.5
6.0
18
4.3
19
2.9
20
1.4
Note: The result is not precise, yield of alcohol
varying under the conditions of fermentation.—
Adapted from Grapes Into Wine by Philip M. Wagner.
In using non-California grapes, you
need to test the sugar content in advance.
That is done by a simple little
instrument called a saccharometer,
obtainable at any winemakers’ shop.
This is floated in a sample of the
juice, and a direct reading of sugar
content is taken from the scale. The
correct amount of sugar to add, in
ounces per gallon of juice, is then
determined by reference to the sugar
table.
Saccharometer and hydrometer jar. Instrument
floats at zero in plain water.
It floats higher according to sugar content
of grape juice.
If total acidity, or tartness, is too
high and not corrected, the resulting
352
wine will be too tart to be agreeable.
Again, California grapes are usually
within a satisfactory range of total
acidity. Grapes grown elsewhere are
often too tart, and acidity of the juice
should be reduced.
In commercial winemaking this is
done with precision.
The home winemaker rarely makes
the chemical test for total acidity but
uses a rule of thumb. He corrects the
assumed excess of acidity with a
sugar solution consisting of 2 pounds
of sugar to 1 gallon of water—adding
1 gallon of the sugar solution for
every estimated 4 gallons of juice.
This sugar solution is in addition to
the sugar required to adjust sugar
content of the juice itself.
In estimating the quantity of juice,
another practical rule is that 1 full
bushel of grapes will yield approximately
4 gallons. The winemaker
therefore corrects with 1 gallon of
sugar solution for each full bushel of
crushed grapes.
The pigment of grapes is lodged
almost entirely in the skins. It is
during fermentation “on the skins”
that the pigment is extracted and
gives red wine its color.
How to proceed. Crush the grapes
directly into your fermenter (a clean
open barrel, plastic tub or large crock,
never metal). Small hand crushers
are available, but the grapes may be
crushed as effectively by foot—wearing
a clean rubber boot. Then remove
a portion of the stems, which may
otherwise give too much astringency
to the wine.
Low-acid California grapes are
quite vulnerable to bacterial spoilage
during fermentation. To prevent spoilage
and assure clean fermentation,
dissolve a bit of potassium metabisulfite
(known as “meta” and available
at all winemakers’ shops) and
mix it into the crushed mass. Use ¼
ounce (⅓ of a teaspoonful) per 100
pounds of grapes.
Kevin Hayes A hand-crank grape crusher.
Also use a yeast “starter”. This
comes as a 5 gram envelope of dehydrated
wine yeast, also obtainable at
winemakers’ shops. To prepare the
starter, empty the granules of yeast
into a shallow cup and add a few
ounces of warm water. When all the
water is taken up, bring it to the
consistency of cream by adding a bit
more water. Let stand for an hour,
then mix it into the crushed grapes.
After the meta and yeast are added,
cover the fermenter with cloth or
plastic sheeting to keep out dust and
fruit flies, and wait for fermentation.
If non-California grapes are used,
test and make the proper correction
for sugar content. Then correct the
total acidity by adding sugar solution
as described earlier. In using non-California
grapes, it is desirable, but
not necessary at this point, to add a
dose of meta. A yeast starter is
advisable.
As fermentation begins, the solid
matter of the grapes will rise to form
353
a “cap”. Push this down and mix
with the juice twice a day during fermentation,
always replacing the cover.
When fermentation begins to subside
and the juice has lost most of its
sweetness, it is time to separate the
turbid, yeasty and rough-tasting new
wine from the solid matter. For this
purpose a press is necessary, preferably
a small basket press though
substitutes can be devised.
Be ready with clean storage containers
for the new wine, several
plastic buckets, and a plastic funnel.
The best storage containers for home
winemaking are 5-gallon glass bottles
or small fiberglass tanks.
Beware of small casks and barrels
for several reasons. They are usually
leaky. They are sources of infection
and off-odors that spoil more homemade
wine than any other one thing.
And there is frequently not enough
new wine to fill and keep them full.
Wine containers must be kept full;
otherwise the wine quickly spoils.
Using glass containers, you can see
what you are doing.
With the equipment assembled,
simply bail the mixture of juice and
solid matter into the press basket.
The press basket serves as a drain,
most of the new wine gushing into
the waiting buckets and being poured
from them into the containers. When
the mass has yielded all its “free
run”, press the remainder for what
it still contains.
Fill the containers full, right into
the neck. Since fermentation will continue
for awhile longer, use a stopper
with a fermentation “bubbler” which
lets the gas out but does not let air
in. When the bubbler stops bubbling
and there are no further signs of fermentation,
replace it with a rubber
stopper or a cork wrapped in waxed
paper.
Fermentation bubbler fitted to jar. Left,
water is poured in to level shown. Right,
position of water immediately before a
gas bubble passes through.
Store the wine for several weeks
at a temperature of around 60° F.
Suspended matter in the wine will
begin to settle, and at this temperature
certain desirable reactions continue
to take place in the wine itself.
At the end of this period, siphon the
wine from its sediment, with a plastic
or rubber tube, into clean containers.
At the same time dissolve and add a
bit of the meta already referred to at
the rate of ¼ level teaspoon per
5 gallons of wine. This will protect
against off odors and spoilage but
does not otherwise affect the wine.
Next, transfer the containers to a
place where the wine will be thoroughly
chilled, even down to freezing.
This precipitates more suspended
matter and unwanted ingredients, and
encourages clarification.
Assuming that the wine was made
in early fall, hold it in cool storage
until after the first of the year. By
then it should have “fallen bright”
and be stable. To test its clarity, hold
a lighted match behind the bottle.
The wine is then siphoned once
again from its sediment, and another
354
dose of meta added at the same rate
of ¼ teaspoon per 5 gallons.
If the wine is brilliantly clear, one
container of it may then be siphoned
into wine bottles, corked or capped,
and is ready for immediate use. Despite
the common impression, most
wine does not gain greatly by aging
once it is stable. It continues to
evolve, but not necessarily for the
better.
The rest of the wine is held until
after the return of warm weather to
make sure there will be no resumption
of fermentation, which would blow
corks if the wine was bottled. By
mid-May that hazard will have passed,
and the wine is ready for its final
siphoning, its final dose of the same
quantity of meta, and bottling.
Fining. If in January the wine is not
brilliantly clear, it should be “fined”.
This consists of dissolving in a small
amount of hot water and mixing in,
at the time of siphoning, ordinary
household gelatin at the rate of ¼
ounce (2 teaspoonsful) per 5 gallons.
This will turn the wine milky when
mixed in and will slowly settle, dragging
all impurities and suspended
matter with it. In two weeks to a
month the process of “fining” will be
complete. The wine is then ready to
be siphoned from the fining sediment
and treated as above.
As we have seen, red wine is fermented
“on the skins” in order to
extract the coloring matter and other
ingredients lodged in the skins. In
making white wine, the grapes are
crushed and the fresh juice immediately
separated by pressing so that
it may ferment apart from the skins.
This fresh juice is checked for its
sugar content and acidity, as in preparing
to ferment red wine, and the
proper corrections are made immediately
after pressing. Likewise, a yeast
“starter” is added.
The fermentation takes place in
the same 5-gallon glass containers
that are later used for storage. But as
fermenters they are filled only two-thirds
full as a precaution against
any overflow or unmanageable formation
of bubbles.
When the primary fermentation has
run its course, the several partly-filled
bottles are simply consolidated—filled
full and equipped with bubblers.
Subsequent siphoning from
sediment, chilling, and dosing with
meta are carried out as with red wine.
If fining is necessary, it differs in
one respect: before mixing in the
gelatin, mix in an equal amount of
dissolved tannic acid to remove the
impurities. Tannic acid is obtainable
at drug stores or winemakers’ shops
as a powder. This provides better
settling out of suspended matter.
Dry table wine is a food beverage,
to be used with meals. Sweet wines
are more like cordials.
The making of sweet wines takes
advantage of a characteristic of the
yeast organism, namely, that its activity
dies down and it usually ceases
to ferment sugar into alcohol after a
fermenting liquid reaches an alcoholic
content of around 13%. The secret,
then, is to add an excess of sugar
when correcting the juice of crushed
grapes before fermentation. When
fermentation ceases, there is still
some residual sugar in the juice.
From then on the still-sweet new
wine is treated much as other wine.
The three important differences
are: (1) the wine is siphoned from its
sediment immediately after fermentation,
without the waiting period at
60° F; (2) the chilling begins as soon
as possible; and (3) the dose of meta
added then and at each subsequent
siphoning is doubled (½ teaspoon per
5 gallons instead of ¼ teaspoon)
to guard against spoilage and against
any accidental resumption of fermentation.
Dry table wines made from other
fruits are rarely successful, but agreeable
sweet wines may be made from
355
them. The point to remember is that
most fruits are lower in sugar than
grapes and higher in acid. Corrections
for both are almost always necessary,
plus sufficient excess sugar to leave
residual sweetness after fermentation.
These fruits, with the exception of
apple juice, are fermented in a
crushed mass in order to obtain a
maximum extraction of characteristic
odors and flavors. Once fermentation
is concluded, they are treated like
sweet grape wine. The table will
serve as a rough guide to their relative
sugar content and total acidity.
[C]To maintain proper sugar level when the acidity is reduced by adding water, it is easier to make
up a sugar solution by dissolving 3 pounds of sugar in enough water to fill a 1-gallon jug.
[B]Addition of some acid (citric or tartaric) may help. This can be done “to taste” after the active
fermentation is over.
If a cork happens to pop out unnoticed
and air reaches the wine for
several weeks, there is a good chance
that bacterial action will begin to
convert the alcohol in the wine into
acetic acid. Once the presence of
acetic acid can be detected (a vinegar-like
odor) the wine will lose its appeal
as wine. A usable vinegar can be
retrieved by encouraging the process
to go to completion.
Vinegar produced from an undiluted
wine will be overly strong, so
an equal volume of water should be
added. The container should be less
than three-quarters full and closed
with a loose cotton plug or covered
with a piece of light cloth to keep out
fruit flies.
If wine vinegar is your desired goal
and no wine has started to sour, use
a vinegar starter. A selected strain of
vinegar starter can be purchased from
some winemakers’ shops, or a wild
starter may be used. Frequently the
water in an air-bubbler will have a
vinegar-like smell. This can be used
to start a batch of vinegar. The wine
is diluted with an equal volume of
water and the container partly filled
and covered as above.
A warm, but not hot, location will
speed the process. In a month or two
the vinegar should be ready. The
clear portion of the vinegar can be
poured or siphoned off for use. If
another batch is wanted, more of the
wine-water mixture can be added to
the old culture.
356
Home Drying of Fruits and Vegetables — Procedure — Steps in Drying Fruits and Vegetables — Pretreating — Drying — Conditioning and Storing
Tasty ready-to-eat snacks and confections
are some of the versatile
products you can create by drying
fruits and vegetables at home. After
soaking in water, the rehydrated food
can be used in favorite recipes for
casseroles, soups, stews and salads.
Rehydrated fruits and berries can
also make excellent compotes or
sauces.
Drying is appealing because the
procedure is relatively simple and
requires little equipment. Only minimal
storage space is needed. Food
can be dried in the sun, in the oven,
or in a dehydrator.
Drying requires a method of heating
the food to evaporate the moisture
present, and some means of removing
the water vapor formed.
Sun drying utilizes both radiant
heat energy and heat transferred to
the product from warm air. Natural
air currents are usually adequate to
carry away the water vapor.
Trays of wood slats, plastic mesh,
or aluminum screen may be placed
in the sun on support blocks or
strips to allow air movement around
and through the trays. Galvanized
wire is not recommended as a tray
material because high-acid foods will
react with the zinc coating on the
steel wire.
If insects or birds are a problem,
a wooden frame can be constructed
over the trays to support a plastic
mesh or cheesecloth cover. Further
protection can be provided by using
a totally enclosed frame and a transparent
panel to form a solar drying
oven.
To dry in the kitchen oven, the
thermostat should be set to its lowest
temperature (generally about 150°
F). Since oven vents provided for
removing moisture from roasting and
baking are adequate for drying only
small quantities of food at one time,
the oven door should be left partially
opened. For larger loads, the air circulation
rate can be increased by
placing a household fan outside the
oven, directed at one edge of the
partially opened oven door.
Dehydrator cabinets may be purchased
in many sizes and types. Or
they may be built using plans available
from State universities or U.S.
Department of Agriculture plan services
(ask your county Extension
office about plans). All cabinets are
provided with a heat source and
vents for carrying off moist air.
Simpler units may rely on natural
convection to carry moist air away,
and the heating unit may be limited
in output so that the cabinet never
exceeds safe drying temperatures
near the end of the drying period.
This type will be slow in achieving
drying temperature if sizable amounts
of food are processed at one time.
Trays must be rotated during the
processing period to insure even drying.
Trays nearest the bottom, exposed
to the hottest, driest air, will
dry most rapidly.
If the natural convection type cabinet
is equipped with a thermostat, it
may be fitted with a larger heater.
This will provide higher drying temperatures
during the early stages but
will not give even drying across all
trays.
By using a fan to force air across
the trays more rapidly, even drying
can be obtained across each tray as
well as between trays. The forced air
system may be used with or without
a thermostat.
357
Most food products release moisture
rapidly during early stages of
drying. This means they can absorb
large amounts of heat and give off
large quantities of water vapor while
remaining at a temperature well below
that of the drying air. Maximum
drying rates can be achieved by providing
a larger, thermostatically-controlled
heat source and a fan for
circulating air.
Enclosed frame solar drying oven
with provision for air movement.
air in (screened)
trays
glass or transparent plastic
air out (screened)
Dehydrator with built-in heater
relies on air movement to carry off
moist air.
air in
heating element
heat shield
trays
air out
This forced draft
dryer can recirculate much of the drying
air to conserve energy.
air in
fan
heaters
heat shield
thermostat
trays
air out
To conserve energy and still obtain
rapid, even drying across all trays,
much of the drying air may be reheated
and recirculated. This is particularly
effective during the last 70%
to 90% of the drying period, when
relatively small amounts of water are
absorbed by the air as it passes over
the partially dried food.
The recirculating system requires
either a thermostat or separate switch
controls on part of the heating unit
to adjust heat output to match the
drying load. The amount of air recirculated
is determined by the size of
the permanent inlet and outlet openings
in the box. It can be further
controlled by adjusting the door to
a partially opened position.
Detailed plans for constructing the
recirculation-type drier can be obtained
by sending 25¢ to the Western
Regional Agricultural Engineering
Service (WRAES), Oregon State University,
Corvallis, Oreg. 97331 and requesting
WRAES Fact Sheet No. 18.
Drying is a relatively simple process,
but there are a number of recommended
techniques. You may need
to use a “trial and error” approach
to find the drying procedure which
works best in a particular situation.
Fruits and vegetables can be dried
in pieces or pureed and dried in a
thin sheet as a “leather.”
The following information summarizes
major steps in drying. Detailed
instructions are available at
county Extension offices. Also, various
books on the market give instructions
for drying and recipes for
using dried food.
Fruits and vegetables selected for
drying should be the highest quality
358
obtainable—fresh and fully ripened.
Wilted or inferior produce will not
make a satisfactory dried product.
Immature produce lacks flavor and
color. Overmature produce may be
tough and fibrous or soft and mushy.
PREPARE
wash, sort
peel, pit/core, slice
PRETREAT
fruits:
dip or blanch
vegetables:
blanch
DRY
oven, sun, dehydrator
CONDITION AND STORE
equalize, pasteurize
package and store
Prepare produce immediately after
gathering, and begin drying at once.
Wash or clean all fresh food thoroughly
to remove any dirt or spray.
Sort and discard defective food; decay,
bruises, or mold on any piece
may affect an entire batch.
For greater convenience when you
finally use the food, and to speed
drying, it is advisable to peel, pit, or
core some fruits and vegetables.
Smaller pieces dry more quickly and
uniformly.
Enzymes in fruits and vegetables
are responsible for color and flavor
changes during ripening. These
changes will continue during drying
and storage unless the produce is pretreated
to slow down enzyme activity.
Blanching is the recommended pretreatment
for vegetables. It helps save
some of the vitamin content, sets
color, and hastens drying by relaxing
tissues. Blanching may also prevent
undesirable changes in flavor during
storage, and improve reconstitution
during cooking.
Steam blanching is preferred because
it retains more water-soluble
nutrients than water blanching.
Blanching times differ, depending on
the type of vegetable being dried.
Overblanching leads to excessive
leaching of vitamins and minerals.
Inadequate blanching will not destroy
enzymes that cause vitamin loss during
drying and storage.
Many light-colored fruits (especially
apples, apricots, peaches, nectarines,
and pears) tend to darken
during drying and storage. To prevent
this darkening, the fruit may be
pretreated by blanching or by a suitable
dip, but effectiveness of pretreatment
methods varies.
Fruit may be dipped in one of the
following:
—A solution of table salt
—A solution of ascorbic acid. Commercial antioxidant mixtures containing ascorbic acid may also be used, but often are not as effective as pure ascorbic acid.
Fruits may be steam-blanched.
However, blanched fruits may turn
soft and become difficult to handle.
Sirup blanching may help retain
the color of apples, apricots, figs, nectarines,
peaches, pears and plums.
A sweetened candied product will
result.
Fruits with tough skins (grapes,
prunes and small dark plums, cherries,
figs, and some berries) may be
water-blanched to crack the skins.
This will allow moisture inside to
surface more readily during drying.
Before drying pretreated food, remove
any excess moisture by placing
the food on paper towels or clean
cloths. Drying trays should be loaded
with a thin layer of food as directed.
If needed, clean cheesecloth can be
spread on the trays to prevent food
pieces from sticking or falling
through.
The amount of food being dried at
359
one time should not exceed that recommended
by instructions.
A temperature of 135° to 140° F
is desirable for dehydrator and oven
drying. Moisture must be removed
from the food as fast as possible at
a temperature that does not seriously
affect the food’s flavor, texture, color,
and nutritive value.
If the initial temperature is too low
or air circulation insufficient, the
food may undergo undesirable microbiological
changes before it dries
adequately.
If the temperature is too high and
the humidity too low, as when drying
small loads in the oven, the food
surface may harden. This makes it
difficult for moisture to escape during
drying.
Oven or dehydrator drying should
continue without interruption to prevent
microbial growth.
To promote even drying, rotate
trays occasionally and stir food if
necessary.
Drying time varies according to
fruit or vegetable type, size of pieces,
and tray load. Dehydrator drying
generally takes less time than oven
drying. Sun drying takes considerably
more time.
Before testing foods for desired
dryness, remove a handful and cool
for a few moments. Foods that are
warm or hot seem softer, more moist,
and more pliable than they will when
cooled.
Foods should be dry enough to prevent
microbial growth and subsequent
spoilage. Dried vegetables
should be hard and brittle. Dried
fruits should be leathery and pliable.
For long term storage, home dried
fruits will need to be drier than commercially
dried fruits sold in grocery
stores.
Fruits cut into a wide range of
sizes should be allowed to “sweat” or
condition for a week after drying to
equalize the moisture among the
pieces before placing in long term
storage. To condition, place fruit in
a non-aluminum, non-plastic container
and put in a dry, well-ventilated
and protected area. Stir the
food gently each day.
Dehydrated foods are free of insect
infestation when removed from
the dehydrator or oven. However,
sun-dried foods can be contaminated
and should be treated before storage.
Insects or their eggs can be killed by
heating dried food at 150° F for 30
minutes in the oven. An alternative
is to package the food and place it in
the home freezer for 48 hours.
Dried foods should be thoroughly
cooled before packaging. Package in
small amounts so that food can be
used soon after containers have been
opened.
Pack food as tightly as possible
without crushing into clean, dry, insect-proof
containers. Glass jars or
moisture-vapor proof freezer cartons
or bags (heavy gage plastic type)
make good containers. Metal cans
with fitted lids can be used if the
dried food is first placed in a plastic
bag.
Label packaged foods with the
packaging date and the type of food.
Store containers of dried foods in
a cool, dry, dark place. Check food
occasionally to insure that it has not
reabsorbed moisture. If there is any
sign of spoilage (off-color or mold
growth), discard the food. Food affected
by moisture, but not moldly,
should be used immediately or re-heated
and repackaged.
All dried foods deteriorate to some
extent during storage, losing vitamins,
flavor, color, and aroma. However,
low storage temperatures prolong
storage life, and dried foods may be
frozen for long term storage.
Dried foods can be reconstituted
by soaking, cooking, or a combination
360
of both, and will resemble their
fresh counterparts after reconstitution.
However, dried foods are unique
and should not be expected to resemble
a fresh product in every
respect.
Drying does not render the food
free of bacteria, yeasts, and molds.
Thus, spoilage could occur if soaking
is prolonged at room temperature.
Refrigerate if soaking for longer than
1 to 2 hours.
To conserve nutritive value, use the
liquid remaining after soaking and
cooking as part of the water needed
in recipes.
One cup of dried vegetables reconstitutes
to about 2 cups. To replace
the moisture removed from most
vegetables, barely cover them with
cold water and soak 20 minutes to 2
hours. Cover greens with boiling
water. To cook, bring vegetables to a
boil and simmer until done.
One cup of dried fruit reconstitutes
to about 1½ cups. Add water just to
cover the fruit; more can be added
later if needed. One to eight hours
are required to reconstitute most
fruits, depending on fruit type, size
of pieces, and water temperature.
(Hot water takes less time). Over-soaking
will produce a loss of flavor.
To cook reconstituted fruit, cover and
simmer in the soak water.
Dried or reconstituted fruits and
vegetables can be used in a variety
of ways.
Use dried fruit for snacks at home,
on the trail, or on the ski slopes. Use
pieces in cookies or confections.
Serve reconstituted fruit as compotes
or as sauces. It can also be
incorporated into favorite recipes for
breads, gelatin salads, omelets, pies,
stuffing, milkshakes, homemade ice
cream and cooked cereals.
Add dried vegetables to soups and
stews or vegetable dishes. Use as dry
snacks or dip chips.
Include reconstituted vegetables in
favorite recipes for meat pies and
other main dishes, as well as gelatin
and vegetable salads.
Powdered vegetables in the dried
form make a tasty addition to broths,
raw soups, and dressings.
Some vitamin breakdown occurs
during drying and storage of dried
fruits and vegetables. Ascorbic acid
(Vitamin C) is the vitamin most likely
to be lost.
Nutritive losses can be kept to a
minimum by:
—Blanching the correct length of time
—Packaging dried foods properly and storing containers in a cool, dry, dark place
—Checking dried foods periodically during storage to insure that moisture has not been reabsorbed
—Eating dried foods as soon as possible
—Using liquid remaining after reconstitution in recipes
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Storage of Home-Preserved Foods — Home Frozen Foods — Don’t Open
Proper storage of home-preserved
foods, especially of home-canned
products, and close scrutiny before
serving are essential. If proper storage
requirements are not met, home-preserved
foods may lose their quality
or spoil.
Homemakers should observe some
simple techniques for checking home-canned
foods before serving them.
This will help prevent consumption
of food that could cause the rare but
extremely dangerous food poisoning
called botulism.
Most canned foods are highly perishable
yet do not require refrigeration
until opened. Unlike frozen
foods, they are unaffected by power
interruptions or mechanical failures.
However, the hazard of botulism
must always be kept in mind. Although
botulism is rare, it results in a
high death rate of about 65 percent
among its victims. Yet it is an easy
problem to avoid. Botulism results
when home-canned foods are improperly
processed. Under these conditions,
the spore (a seed-like structure
which is highly heat-resistant) of
a soil bacterium called Clostridium
botulinum may survive.
If the food product is low in acidity,
as with peas, corn, or beans, the
spore can germinate (sprout) and
grow during storage at room temperatures.
As Clostridium botulinum
grows, it produces a powerful poison
that when ingested can cause severe
illness or death. Most cases of botulism
in the United States stem from
home-canned foods.
The home canner can avoid botulism
primarily by following prescribed,
reliable processing instructions
such as those given in USDA
Home and Garden Bulletin No. 8,
Home Canning of Fruits and Vegetables.
If you don’t have reliable processing
instructions, don’t attempt
home canning. If you have these instructions,
read them before and during
home canning and do not take
short cuts or modify the instructions.
Do not use processing instructions
of neighbors or relatives; although frequently
given with the best of intentions,
they may contain modifications
that are inadequate and dangerous.
Remember that past safe history of a
relative’s processing procedure is no
guarantee of future safety. Botulism
doesn’t always occur even in inadequately
processed home-canned
foods.
After home-canned foods have
cooled they are ready to be stored
until needed. At this point, the home
canner should make his first quality
control and safety check, just as commercial
canners do.
Jar lids should be examined. If the
center of the lid is not depressed or is
loose, refrigerate the product immediately
and serve at the next meal.
Before serving, boil low acid products
for 10 minutes. Check all jars for
cracks; if they are found, treat jars
the same way as those with loose
lids.
Observe cans for any evidence of
leakage around seams; again if leakage
is observed, refrigerate the cans
immediately, serve at the next meal,
and boil for 10 minutes before
serving.
During this first integrity check on
home-canned foods, it is unlikely that
swelling of the cans or foaming in the
jars will be noticeable, because of the
short lapse of time since processing.
But the first check can easily detect
362
loose lids, cracked jars and leaking
seams on cans.
The next step is to store home-canned
products. Proper storage will
protect the products from loss of
quality and in some cases from spoilage.
Store canned foods in a clean,
cool, dry area away from bright light—particularly
sunlight—and in an
area where the foods will not freeze
or be exposed to high temperatures.
Under these conditions, the products
will remain at high quality for at least
a year.
Excessive dampness will rust cans
or metal lids. If this condition becomes
severe, leakage will occur and
the product will spoil. Freezing
causes expansion of the product and
the jar lid may loosen, the jar may
crack, or can seams may be stressed.
This can lead to leakage and food
spoilage.
When foods are preserved by heating,
as in home canning or commercial
canning, the heating process is
designed to destroy all normal spoilage
bacteria that can grow under
usual storage conditions, and all bacteria
capable of causing human harm.
The products are called “commercially
sterile” but are not always
truly sterile.
A group of bacteria produce extremely
heat-resistant spores that can
only germinate and grow at high storage
temperatures such as those above
103° F. These bacteria often survive
both the home and commercial canning
process. Even though present,
they normally are of little concern
from the viewpoint of spoilage and
no concern at all from the standpoint
of human health. However, if canned
foods are stored in attics or near hot
water pipes or in any other area
where the temperature will exceed
102° F at any time, these heat-loving
bacteria (called thermophilic) can
grow and spoil the product.
Fred Farout Boil home-canned low-acid foods 10
minutes before tasting or serving.
As a rule of thumb, home-canned
foods will remain high in quality for
one year if properly stored. After a
year, loss of quality may occur.
Containers for home-preserved
foods are designed to resist any chemical
reactions between the product
and the containers. However, some
products—particularly high acid ones
like tomatoes—will slowly react with
the metal in the can or the jar lid.
Corrosion and container failure may
follow during subsequent storage.
This action occurs from the inside out
and can take place even under good
storage conditions.
Jars should be dated when stored,
and used within a year from the
processing date. Always rotate stock
on the shelves so as to use the oldest
container first, and can no more units
of any single product than you can
use in a year.
The last and perhaps most important
quality control steps are the final
inspection and serving procedures.
After removing the product from
storage, carefully inspect the container,
and in the case of jars the
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visible contents. This should be done
before opening.
If a can or jar lid shows any sign of
swelling (bulging) or leakage of product,
do not open the container. If a
jar lid is loose or the contents of a
jar are foamy or otherwise visibly abnormal,
do not open. When any of
these defects are noted, place the
whole container in a heavy plastic
bag and tie the top securely. Place
this in doubled paper bags with heavy
packing of newspapers. Tape or tie
the top securely, place in a lidded
garbage can, then wash your hands
thoroughly.
Not all spoiled or leaking home-canned
foods contain the deadly botulism
toxin but some do, so extreme
caution in disposal is necessary.
If a defective product is found, all
of that product prepared at the same
time should be removed from storage
and similarly inspected.
Never taste the contents of a suspect
product. Under certain circumstances,
a spoonful of “off” unheated,
suspect product has been known to
kill.
Finally, bring all home-canned vegetables
to a rolling boil after opening
and before tasting. Heating makes any
odor of spoilage more noticeable.
Again, if an odor of spoilage is noted,
destroy the product with caution. If
the product is normal, cover the pan
and continue to boil at least 10 minutes
before serving. Only after these
precautions are taken are home-canned
vegetables safe to taste and
serve.
A plus for home freezing is that
slight variations in following directions
do not result in a botulism hazard.
The bacterium that causes botulism
cannot grow in the freezer.
Proper freezing prevents the growth
of microorganisms that cause spoilage
and those that can cause illness.
Besides the initial cost of the
freezer itself, energy costs are significant.
Utilize the freezer fully to keep
the energy costs per unit as low as
possible. Fill the freezer when foods
are least expensive, use the products
as needed, and be careful to use the
oldest products first.
Take care not to overload the
freezer. If you pack it too tightly with
containers of warm food, the freezer
will be unable to remove the heat fast
enough and spoilage from bacterial
growth can result.
To avoid this, freeze foods soon
after they have been packed; put no
more unfrozen food into a home
freezer than will freeze within 24
hours. Usually, this will be about 2
or 3 pounds of food to each cubic
foot of capacity.
For quickest freezing, place packages
against freezing plates or coils
and leave a little space between packages
so air can circulate.
Small excesses of product destined
for freezing can be held in the refrigerator
until the first load is frozen.
If a large excess of product exists,
chill and carry it in an insulated box
or bag as soon as possible to a locker
plant.
After freezing, packages may be
stored close together. Store them at
0° F or below in order to retain the
highest quality for the longest time.
Prolonged storage of frozen foods
results in slow loss of quality. The
rate of this loss differs with various
foods. To maintain high quality, obtain
information on recommended
storage periods for the foods you
freeze. This may be obtained from
your county Extension office or from
USDA Home and Garden Bulletin
No. 10, Home Freezing of Fruits and
Vegetables.
Storage periods are recommended
to guarantee food quality only. If
these periods are exceeded, taste may
be affected but as long as the product
has been kept at 0° F or below there
is no question of safety.
364
The homemaker’s greatest concern
with a home freezer is mechanical or
power failure, which can result in
food losses. Some but not all of these
can be avoided. Freezers are very dependable
mechanical devices yet they
do fail. Most failures develop after 5
or more years of use.
The homeowner should clean dust
from coils of the freezer once or
twice each year in strict accordance
with the instruction manual for the
unit. At this time watch for any
changes that have occurred. Have a
dealer or repairman check unusual
noises or excessive running.
Air circulation around the coils
should not be covered or blocked in
any way. Check the plug itself for
a firm fit. If the plug is loose in the
receptacle, it may fall or be easily
bumped out without notice. Replace
loose plugs. Better yet, some hardware
stores sell clips that clamp the
plug in by means of the screw that
holds the receptacle plate onto the
outlet.
Freezer owners should know where
the closest commercial freezer is, in
case of an extensive failure. Check
your home freezer after thunderstorms
or power failures, since freezers
have been known to be damaged
occasionally when power falls or
surges.
A well packed freezer will hold the
product for many hours even if the
unit is not operating. Normally, power
failures are short in duration and no
food thawing results. If the power is
off, do not open the freezer as this
will hasten thawing. Telephone or
otherwise determine when the power
will be turned on again.
Sometimes freezer failure is discovered
only when a homemaker goes
to the freezer to get something. If this
occurs, condition of the food should
be determined immediately. Discard
all foods that are thawed and warm,
since extensive bacterial growth may
have taken place.
Foods may be saved if they remain
frozen; or if they are thawed but
very cold, about 40° F, and have been
held no longer than 1 or 2 days at refrigerator
temperatures after thawing.
Bacteria grow only slowly in thawed
but cold foods. Prompt refreezing of
thawed cold foods will lower the
quality but not result in spoilage or
danger. If you have doubt as to
whether the foods are cold or warm,
throw them out as the safest course.
Once condition of the foods is determined,
plan fast for the next step.
If the freezer cannot be repaired
quickly, make arrangements to move
the food to a commercial locker plant
or another freezer. To do so, package
the products closely together in paper
bags. Place these in cardboard cartons
lined and covered with newspapers
for insulation, and transfer
them immediately.
Another way to save the freezer
load is to use dry ice in the freezer
itself. Dry ice must be handled with
gloves to prevent burns. Also keep
in mind that carbon dioxide gas
evolves as dry ice evaporates, and
can cause unconsciousness if allowed
to concentrate.
When transporting dry ice, leave a
car window open at least several
inches. If you use dry ice in the
freezing compartment, make sure a
nearby window is cracked open.
When packing dry ice into a freezer,
figure on 25 to 50 pounds to do the
job. Don’t break up the ice any more
than necessary.
To summarize, frozen foods are
seldom involved in food spoilage or
food poisoning. Even so, mechanical
devices occasionally fail, and freezer
owners should have prearranged
plans for such an emergency. Preventive
maintenance will help reduce
the likelihood of failure. If a failure
results in food becoming thawed and
warm, discard it for safety.
365
Storing Fresh Fruit and Vegetables — Root Crops — Tomatoes — Onions — Apples, Pears — Home Storage Chart — Other Fruit — For Further Reading:
Many fruits and vegetables can
be stored fresh. But the home gardener
must gather them at proper
maturity and observe correct temperature,
humidity, ventilation, and
cleanliness rules.
Basements or outdoor cellars can
serve as temporary storage for some
produce. A cellar mostly below
ground is best for root vegetables.
It can be run into a bank and covered
with 2½ feet or more of soil. Sometimes
outdoor root cellars are made
with a door at each end. Combining
the outdoor storage cellar with a
storm shelter in the event of tornadoes
or other needs may be a satisfactory
solution.
Modern basements are generally
too dry and warm for cool moist
storage. However, a suitable storage
room may be built by insulating walls
and ceiling and ventilating through a
basement window. You may ventilate
by extending a ventilating flue from
half of the window down almost to
the floor. Cover the other half of the
window with wood and the outside
openings of the ventilator with a wire
screen for protection against animals
and insects.
Keep the room cool by opening the
ventilators on cool nights and closing
them on warm days. If properly
cooled, the room temperature can be
controlled between 32° and 40° F
during winter. To maintain the humidity,
sprinkle water on the floor
when produce begins to wilt. A slatted
floor and slatted shelves will provide
floor drainage and ventilation.
A reliable thermometer is needed for
operation of any home storage room.
A cool corner in the basement, a
back room of a small house with no
basement, or a trailer may be suitable.
One lady we know uses part of a
closet built into the outside corner of
a bedroom. It is also possible to adapt
storage sheds in carports by insulating
and proceeding as outlined
earlier.
Pits and trenches or mounds may
be used for storage if a root cellar is
not available or basement storage is
impractical. Also, you may bury a
barrel, drainage tile, or galvanized
garbage can upright, with four inches
of the top protruding above ground
level. This will keep potatoes, beets,
carrots, turnips, and apples through
winter. For convenience, place the
produce in sacks or perforated polyethylene
bags of a size to hold enough
for a few days. Then you can easily
take out fruits and vegetables as
needed.
Place the barrel on a well drained
site, and make a ditch so surface
water will be diverted and not run
into the container. A garbage can
has a good lid, but for a drainage tile
or barrel a wooden lid may have to
be built. The lid should be covered
with straw, and a waterproof cover
of canvas or plastic placed over the
straw.
Requirements of fruits and vegetables
differ. Controlled cold storage
or refrigerated storage are best.
Good references are Storing Vegetables
and Fruits in Basements, Cellars,
Outbuildings, and Pits, USDA
Home and Garden Bulletin No. 119,
and bulletins on this subject prepared
by your State Extension service. Your
county Extension office may have the
bulletins. This office may also be
able to tell you how to obtain plans
for a fruit and vegetable storage
room, or a storm and storage cellar.
366
Brief notes on specific storage
problems follow:
With proper care, hard-rind varieties
of winter pumpkins and squash
will keep for several months. Harvest
before frost, and leave on a piece of
stem when you cut them from the
plants.
Store only well-matured fruits that
are free of insect damage and mechanical
injuries.
Pumpkins and squash for long-term
storage keep better when cured for
10 days at 80° to 85° F. If these temperatures
are impractical, put the
pumpkins and squash near your furnace
to cure them. Curing hardens the
rinds and heals surface cuts. Bruised
areas and pickleworm injuries, however,
cannot be healed.
After curing pumpkins and squash,
store them in a dry place at 55° to
60° F. If stored at 50° or below,
pumpkins and squash are subject to
damage by chilling. At temperatures
above 60°, they gradually lose moisture
and become stringy.
Acorn squash keep well in a dry
place at 45° to 50° F for 35 to 40
days. Do not cure acorn squash before
storing them. They turn orange,
lose moisture, and become stringy if
cured for 10 days at 80° to 85° or if
stored at 55° or above for more than
6 to 8 weeks.
A dark green rind at harvest indicates
succulence and good quality.
Do not store pumpkins and squash
in outdoor cellars or pits.
Parsnips, Salsify, Horseradish can
be left undug (stored) in the ground.
These vegetables withstand freezing,
but alternate freezing and thawing
damages them. If you store them
in the ground, mulch lightly at the
end of the growing season. Keep
them covered until outdoor temperatures
are consistently low. Then remove
the mulch to permit thorough
freezing. After they have frozen,
mulch deep enough to keep them
frozen.
Some fruits and vegetables can be
stored outdoors in a partially buried
galvanized garbage can or wooden barrel.
waterproof cover
straw
drainage ditch
garbage can or wooden barrel
Root crops such as beets, carrots,
celeriac, kohlrabi, rutabagas, turnips,
and winter radishes should not be
put in storage until late fall. Root
crops keep best between 32° and 40°
F. They require high humidity to prevent
shriveling. Continued storage at
45° causes them to sprout new tops
and become woody.
Large and overmature root crops
may become tough and stringy in
storage. Small and immature root
crops probably will shrivel.
Dig root crops when the soil is dry
and the temperature consistently low.
Prepare them immediately for storage.
Cut the plant tops about a half inch
above the crown. Beets will bleed
unless 2 to 3 inches of the top is left.
You may wash the roots if you let
them dry again before storing. Do not
expose them to drying winds, and
be sure they are cool when put in
storage.
Prevent bitterness in carrots by
storing them away from fruits such as
apples, which give off volatile gases
while ripening.
Turnips and rutabagas give off
odors, so don’t store them in your
basement. Find a separate spot, or
store them with other root crops and
vegetables in an outdoor cellar or pit.
367
Turnips may be left in the garden
longer than most other crops. They
withstand hard frosts, but are damaged
by alternate freezing and thawing.
All other root crops can be
stored together in your basement storage
room.
VEGETABLE-FRUIT STORAGE GUIDE
Low Humidity
80-85
cure pumpkins, squash
55-60
pumpkins, squash
45-50
acorn squash
32
onions
High Humidity
80-85
cure sweet potatoes
70
mature green tomatoes—to ripen
55-60
tomatoes at mature green stage—to store sweet potatoes
Root crops keep their crispness
longer when bedded in layers of moist
sand, peat, or sphagnum moss. However,
perforated polyethylene bags
and box liners are easier to use than
bedding. Root crops can be stored in
crates or boxes in moist air, but they
gradually lose moisture and quality
unless polyethylene liners are used.
Carrots and beets may be stored in
10-gallon crocks or any container that
will prevent excessive shriveling.
Quick dipping of dried and trimmed
turnips, rutabagas, or parsnips in wax
will prevent shriveling. Float a layer
of jelly-type paraffin on top of a kettleful
of heated water which is deep
enough to cover the vegetable. Dip
room temperature vegetables quickly
through the layer of wax.
For a thinner, harder wax film add
a little salt and 10 to 20 percent clean
beeswax.
Potatoes are the principal root
crops you will probably store. Potatoes
are eaten from the time they are
of sufficient size for early use until
storage time, and during storage when
the vines have fully ripened.
If potatoes are harvested before
maturity the skin may flake off easily.
They are all right for immediate
use, but not for storage. Immature potatoes
shrink badly, bruise easily, and
will not keep well very long.
For storage, potatoes should be
allowed to mature and develop a
thick skin. When the tops lie down
the tubers should be mature enough
for storage.
Dig potatoes carefully to avoid
bruises, for better storage life.
Handle newly dug potatoes with
care until the surface has dried or
cured a few hours or more. You can
keep them in baskets or slatted crates
in single layers at first.
Store sound mature tubers in darkness
at a minimum relative humidity
of 95 percent and 45° to 48° F for
highest quality. For very long storage
keep at a temperature of 38° to 40°
to prevent sprouting. The starch
changes to sugar if potatoes are held
below 45°. Potatoes may not show
any external effect from exposure to
these lower temperatures, but sometimes
darkened tissue will be seen if
the potato is cut and exposed to air.
Light causes considerable “greening”
in potatoes. The green portion
contains an undesirable substance
that gives a bitter flavor.
Sweet potatoes that are well matured,
carefully handled, properly
cured, and stored at 55° to 60° F can
be kept until April or May.
368
Sweet potatoes are easily bruised
and cut. Handle them carefully and
as little as possible. Put them directly
in storage containers at harvest.
Cure freshly dug sweet potatoes by
holding them about 10 days under
moist conditions at 80° to 85° F. In
the absence of better facilities, sweet
potatoes can be cured near your furnace.
To maintain high humidity during
curing, stack storage crates and
cover them with paper or heavy cloth.
If the temperature near your furnace
is between 65° and 75°, the curing
period should last 2 to 3 weeks. After
curing, move the crates to a cooler
part of your basement or house where
a temperature of about 55° to 60°
can be maintained.
In houses without central heating,
sweet potatoes can be kept behind a
cookstove or around a warm chimney.
If you keep sweet potatoes this way,
wrap them in fireproof paper (to slow
down temperature changes) and store
them in boxes or barrels.
Sweet potatoes are subject to damage
by chilling. Do not store them at
50° F or below.
Outdoor pits are not recommended
for storing sweet potatoes, because
dampness of the pits encourages
decay.
Even though the home canner has
canned plenty of tomatoes, it may be
desirable to keep some of the fresh
fruit. Keep tomatoes in the garden as
long as possible. You can protect
against early fall frosts by covering
the plants with burlap or old carpets
in the evening when frost is predicted.
Polyethylene may also be used
but injury will occur wherever it
touches the plant.
In the summer, tomatoes should be
harvested when fully vine-ripened for
best quality. Pick when the color is a
dark red in red varieties. During fall
when frost is likely, mature green
fruit can be picked and it will develop
a red color when kept in a fairly
warm place. The fruit is in the “mature-green”
state if the tissues are
gelatinous or sticky when the tomato
is cut and the tomato interior is yellowish.
Immature green tomatoes
don’t ripen satisfactorily.
To check your judgment, cut a tomato
in half that you feel is mature
green. If the pulp that fills the compartments
is jelly-like, it is mature
green. The seeds are dragged aside
easily by the knife and not cut
through. In immature green tomatoes,
seeds are easily cut through and the
jelly-like pulp has not yet developed.
Usually you can recognize the mature
green ones by their glossiness, less
hairiness, and more whitish green
color.
You can pick mature-green fruits
and bury them in deep straw or place
in a room where the temperature is
60° to 70° F. The tomatoes will ripen
over a period of 3 or 4 weeks. Sunlight
is not needed to ripen green-ripe
tomatoes, so don’t bother to put them
on window sills. They ripen satisfactorily
in the dark. Generally, tomatoes
store best at 55° to 60° and ripen at
70° or room temperature.
You can wash the mature green
fruits in a weak solution of household
bleach and then wrap in paper to
store and ripen.
Some people pull up the vines just
before frost and hang them in the
basement or garage to ripen their
fruit.
Harvest onions for storage when
the neck of the plant dries down, the
tops have fallen over, and the roots
are dry and have stopped growing
from the stem plate. At that time the
outer scales of the bulb are drying out
and do not cling tightly (outer scales
of yellow-skinned varieties change to
a darker color).
Pull the onions by hand and lay in
a windrow to cure with the tops
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placed over the bulbs to prevent sun-scald.
Onions may also be cured in
an open shed. Remove onions with
thick neck (seeders) before storage
and discard all diseased bulbs.
After curing, place onions in open-slatted
crates or burlap bags for further
field curing or drying. Then place
in storage. You may use either common
storage or refrigerated storage.
Low temperatures in storage reduce
shrinkage due to moisture loss
and stop disease development. Keep
the humidity as low as possible. Good
management of ventilation is important.
Ventilate storage early in the
morning.
Onions held in cold storage should
be placed there immediately after
curing. A temperature of 32° F is ideal
and will keep onions dormant and
relatively free of rot. If sprouts grow
it indicates too high a temperature,
poor curing, or immature bulbs. If you
have root growth the humidity is too
high. The humidity should be 65 to 70
percent.
Do not store onions with produce
that is likely to absorb the odor.
Onions stand slight freezing, but do
not handle or move them until they
thaw. You can store onions in a dry,
well ventilated attic or unheated
room. Maintain as near 32° F as you
can and keep as dry as possible. You
can hang open-mesh bags, about half
full, from overhead hooks or nails.
Slatted half full crates of onions may
be stacked on cross bars.
Chemical changes take place in the
ripening process of apples and pears.
This activity is called respiration.
Starch changes to sugar, acids and insoluble
pectins decrease, and volatile
gases are given off. This continues
until the fruit becomes overripe
and mealy. During this ripening
process oxygen is consumed from the
air, and water and carbon dioxide are
produced and heat is generated.
You may slow respiration by cooling
fruit as rapidly as possible after
picking. The sooner this is done the
longer the fruit will keep.
Research indicates that when
apples are stored at 30° F, about 25
percent more time is required for
them to ripen than at 32°. Stored at
40°, the rate of ripening is about
double that at 32°. At 60° the rate
is close to three times that at 40°,
and at 85° the softening and respiration
rates have been found to be
about double those at 60°. This emphasizes
the importance of cooling
quickly and keeping cold. The average
freezing point of apples is about
28° or 29°.
Most apple varieties keep best at
a temperature of 30° to 32° F and a
relative humidity of 85 to 88 percent.
However, McIntosh, Yellow Newton,
and Rhode Island Greening apples do
best at 35° to 38°. This prevents internal
browning and brown core.
Pears can be stored ideally at 30°
to 31° F. The highest freezing point
for pears is about 29°. Since pears
are likely to shrivel, keep the humidity
at 90 percent. Most pears won’t
ripen satisfactorily for eating at the
above temperatures. They should be
taken out of storage and ripened between
65° and 70°. This is ideal for
Bartletts.
Bartlett pears ripen faster than
apples. If you store pears too long
they will not ripen properly. Don’t
store Bartletts after 3 months or Anjou
longer than 6 months.
Maintaining desired temperatures
for home storage of apples and pears
may be difficult. If you must settle
for 40° F or even higher, you won’t
get the good results you would if
you refrigerate at the optimum temperatures.
Sometimes cold storage
facilities are available where you
may store your fruit for a set price
per container.
Don’t mix windfalls (fruits that
have dropped to the ground) with
370
fruit you pick from the tree. Windfalls
are overripe and give off ethylene
gas which speeds ripening of
picked fruit.
Desirable temperatures may be possible
in refrigerator hydrator drawers
for small quantities.
An extra refrigerator can be used
to store fruit, but do not take the
shelves out. When it is empty, for
safety reasons take off the doors.
Storage conditions
Where to store
Temperature (F)
Humidity
Storage period
Vegetables:
Beans and peas, dried
Any cool, dry place
32-40
Dry
Many Years
Beets
Storage cellar or pit
32-40
Moist
Fall-winter
Cabbage
Storage cellar or pit
32-35
Moist
Fall-winter
Carrots
Storage cellar or pit
32-40
Moist
Fall-winter
Celery
Roots in soil in storage cellar
32-40
Moist
Fall-winter
Onions
Any cool, dry place
As near 32 as possible
Dry
Fall-winter
Parsnips
Leave in ground or put in storage cellar
32-40
Moist
Fall-winter
Potatoes
Storage cellar or pit
45-48
Moist
Fall-winter
Pumpkin, winter squash
Unheated room or basement
55-60
Dry
Fall-winter
Rutabagas
Storage cellar or pit
32-40
Moist
Fall-winter
Sweet Potatoes
Unheated room or basement
55-60
Dry
Fall-winter
Tomatoes (green or white)
Unheated room or basement
55-60
Dry
1-6 weeks
Turnips
Storage cellar or pit
32-40
Moist
Fall-winter
Fruits:
Most apples
Fruit storage cellar
30-32
Moist
Fall-winter
McIntosh, Yellow Newton & Rhode Island Greening
Fruit storage cellar
35-38
Moist
Fall-winter
Grapes
Fruit storage cellar
31-32
Moist
4-6 weeks
Pears
Fruit storage cellar
30-31
Moist
Fall-winter
Peaches
Fruit storage cellar
32
Moist
2 weeks
Apricots
Fruit storage cellar
32
Moist
2 weeks
Storing fresh cherries, peaches, and
apricots very long is difficult. Refrigerate
as close to 32° F as possible.
Peaches ripen well at 65° to 85° and
refrigerate well in hydrators for as
long as 4 weeks. Peaches may be
stored in walk-in refrigerators in
larger quantities.
Grapes are generally not adapted
to long storage. Concord grapes may
be stored 4 to 6 weeks at 31° to 32° F.
Catawba and Delaware varieties can
be held 8 weeks. Vinifera table grapes
such as Emperor and Ribier will keep
3 to 6 months at 30° to 31°.
Since apples, pears, grapes, and
other fruit absorb odors from potatoes,
371
onions, and other vegetables,
store them separately.
Some kitchen garden herbs, such
as chives and parsley, may be potted
and cared for as house plants. These
plants will supply flavoring and garnishing
to enhance wintertime meals.
Trying to predict exactly how long
your fruits and vegetables can be
stored is next to impossible. Much depends
on condition of the product
and how successful you are in
maintaining correct temperatures and
humidity. Generally, you can keep
parsnips and carrots all winter, late
potatoes 6 to 8 months, cabbage 3
months, onions 6 to 10 months, and
pumpkins, squash, root crops, and
tomatoes 3 to 6 months.
Cleanliness. One last precaution:
Keep the storage areas clean and free
of decaying fruit and vegetables;
otherwise, molds and bacteria will
spread to your sound produce.
If you store nuts (especially peanuts),
soybeans, other dry beans or
peas, make every effort to prevent
growth of molds. Moisture, temperature,
and time are necessary to promote
their growth. A harmful toxin
may be produced if mold growth
is allowed to progress. It is important
that storage areas be regularly
checked so as to avoid this type of
contamination.
Discard all produce that shows any
sign of decay.
Insects, rats, and other pests can
spread disease and are unwanted
guests in any food storage area. To
escape these undesirables:
—Build them out. Close all cracks and use adequate screening over all openings
—Prevent trash piles from accumulating
—Keep the storage area clean
—Control rats inside and outside. (Seek the advice of your county Extension office or a sanitarian)
—Destroy any infested food
—Remove all containers at least once a year. Wash them and air dry in the sun
—Remember that good housekeeping practices apply to all places where food is stored
U.S. Department of Agriculture, Storing
Vegetables and Fruits in Basements,
Cellars, Outbuildings, and Pits, H&G
Bul. No. 119, on sale by Superintendent
of Documents, U.S. Government
Printing Office, Washington, D.C.
20402. 40¢.
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Resurgence of Community Canneries — Points to Consider — Major Costs — Regulations — Skills Needed — Hours, Fees
A community cannery is a self-help
facility equipped for preparing and
heat processing food. People bring in
produce from their gardens and
through their own efforts preserve it
for future use.
Community canneries began during
the late 1800’s in response to the desire
of families to work together to
preserve their food for the off-season.
At the end of World War II there
were over 3,800 community canneries
in the United States. Most of these
wartime canneries were subsidized,
but after the war the monies ceased.
Growth of the food industry, development
of freezing techniques, and the
lack of subsidy led to a decline of
the canneries.
Today there is a resurgence of interest
in establishing community canning
centers. This has been influenced
by the cost of food, a marked
increase in the concern for nutrition,
and gardening activities.
A community cannery promotes the
preservation of seasonal garden surpluses
for consumption during the
nonproductive season. It encourages
small farmers and nonfarm individuals
to produce more food, thereby
promoting self-sufficiency for families.
It enables families who do not
own recommended food preservation
equipment to use safe and reliable
equipment and techniques.
Availability of nonseasonal foods
on a year-round basis can result in a
better diet for families, especially if
the center incorporates nutrition education
classes as part of its program.
People who grow their own food
may make substantial savings in
their food budget. The community
cannery creates a social atmosphere
of friendly, cooperative work leading
to tangible results, and promotes a
feeling of self-reliance.
Most of the community canneries
in the country have been organized
by Community Action Agencies or
similar community organizing groups.
Individuals, food co-ops, and other
groups have successfully set up canneries,
but it is recommended that
people wanting to establish a canning
center contact a community organizing
agency. Normally, these agencies
have professional people who will
work on such a project. They have
experience in writing proposals and
are aware of potential funding
sources.
Support for the canning center can
be enhanced by making a special
effort to include a diverse membership
on a board of directors for the
center.
Farmers, low-income people, business
people, contractors, Extension
personnel, community organizers, local
officials, and members of the
clergy are all potential supporters and
advisors for the cannery.
Although organizing a community
cannery requires a lot of work, this
need not be a roadblock to initiating
the project. It takes many hours to
plan the canning operation, draft proposals,
develop community support,
locate a site, and to select, purchase
and install equipment. Because this
can easily be a full-time job for one
person, efforts should be made to hire
a coordinator. In many instances, paid
community organizers, Vista volunteers,
and home economists have provided
valuable assistance in completing
the work.
Preparation for and organization of
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the cannery are the foundation of the
project. At least six months should be
set aside for organizing.
William E. Carnahan Tomatoes in the canning process,
at a community cannery.
William E. Carnahan Sweet corn ready to have kernels removed
for canning.
At later stage,
liquid is poured over hot-packed corn.
Note one advantage of a community
cannery is that quantities of food can
be processed in a few hours.
Here are some questions to consider
before starting a community
center:
How many people will commit
themselves to organizing a center?
How much time will they give?
How much support can be expected
from the community, town officials,
local growers?
How many community and family
gardens are in the area?
How near are the community gardens
to the cannery site?
Is the site near a well-travelled
route?
Is parking available?
Can the canning center exist merely
to provide a service to the community,
or will the cannery have to become
involved in a commercial
venture?
If some food processed at the cannery
is to be sold, are local farmers
willing to contract with the cannery
to supply it with produce? How close
are these farmers to the cannery?
Is a building available for canning
purposes (for example, some old
creamery)?
If so, what is the size of the
building? What is its condition?
Are there cement floors and walls
constructed so they can be washed
down daily?
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Is there room for storage, a walk-in
cooler?
Is the sewage system adequate?
Does the building have existing
equipment that could be put to use?
Is a dependable supply of potable
water available?
What is the minimum water pressure
and is it constant?
Is the water “hard?” If so, what is
the analysis?
What type of electricity is available?
What is the cost of electricity per
KWH and demand rate for 240 volt,
3 phase, 60 cycle?
What is the availability and cost of
gas (natural or LP) or of fuel oil?
What is the number of families expected
to participate? How many are
low-income families?
What are the principal foods to be
canned?
If it is anticipated that some products
will be processed for sale, what
will those products be?
Is there a market for the “for-sale”
items?
Will canning supplies such as jars,
lids, screw bands, tin cans be available?
Can they be purchased at
wholesale prices?
Is at least one person who is knowledgeable
in food preservation methods
available to supervise the cannery?
What will be the charge for processing
a pint or a quart of food?
Will low-income people be able to
pay this amount?
Are funds available to subsidize
the canning of food for low-income
people?
It is important to obtain a site easily
accessible to the public. Selectmen,
property owners, realtors should
be approached for potential sites.
Usually the center has limited funds,
and it is difficult and takes time to
locate an appropriate building with
low-cost rent.
In times of a strained economy
and high cost of property maintenance,
the business community may
be hesitant to provide low-cost housing
for the site.
Establishing the facility in a publicly
owned building, such as a school,
is a solution in many communities.
These canneries are a part of the
public school’s physical plant and
have traditionally been operated
under supervision of the vocational
agriculture and home economics
teachers, using school funds.
In recent years, some schools
have wanted to close canneries for
several reasons: Lack of operating
capital, limited use, lack of interest or
know-how on the part of participants
and teachers. With the resurgence of
interest in canning, many new cannery
ventures are located in schools
but are now funded separately from
school budgets.
If the cannery is the result of a
community endeavor, adjoining small
towns could appropriate funds sufficient
to set up and man a center. Such
a proposal would have to be presented
to the town governing bodies.
This points up the need for ample
planning time. Devising means to allow
the cannery to remain open year-round
would favor obtaining a site
other than in a public building.
Cost of organizing a community
cannery is influenced by its size and
scope of operation. Expenses can be
broken down into these major areas:
At least two companies manufacture
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community canning equipment
(Ball Corp. and Dixie Canner Equipment
Co.). Prices start at $4,300 for
a single-unit operation, and go up to
$20,000 for a large center. This does
not include the price of a steam
boiler, which costs between $3,000
and $5,000. By fabricating some of
its own equipment, and by buying
used equipment from canning and
restaurant equipment suppliers, the
cannery can reduce some of its purchase
costs substantially.
Installation of the canning equipment
and the steam boiler needs to
be done by a licensed plumber or
steam fitter, or be closely supervised
by such a person.
Renovation of a building and installation
of the canning equipment
can cost between $4,000 and $8,000,
including labor costs. Cost can be reduced
by soliciting volunteer labor
from local craftsmen. The organizers
can handle much of the renovation,
such as painting, carpentry and cement
work. Teams of vocational students
may be willing to take on the
site renovations as part of their
school training.
Salaries for employees can be paid
from the cannery’s operating budget.
Labor costs can be reduced if the
workers are already salaried employees
provided by other food-related
agencies. The cannery can
also be an ideal training site for participants
in the Comprehensive Employment
and Training Act (CETA)
and can be staffed successfully in
this way.
Food and Drug Administration regulations
regarding food processing do
not apply to community canning centers
if they are not involved in interstate
commerce. In June, 1976, FDA
issued “Suggested Minimum Guidelines
for Community Canning Operations”
to protect the safety of the
consumer.
Environmental regulations that apply
to the centers must be carefully
followed. Although these regulations
are usually not hard to follow, they
often mean a possibly unplanned-for
expense to the cannery. It may be
necessary to apply for a variance to
zoning regulations. Cannery supervisory
boards should have a working
knowledge of all requirements of
State and Federal agencies that regulate
health, environment, fire, safety,
plumbing, electricity, and public
building codes.
Sites for the centers should have
sewage and draining systems that
meet demands of the centers. This
would mean a septic system and leach
fields, or a municipal sewage system,
the latter being the easiest and least
expensive method of disposal. Solid
waste produced by the center is
termed “clean,” and effluent from
the processing could be put through
a strainer, piped out of the center, and
then deposited into a leach field.
To maintain high standards of
cleanliness and safety, at least one
supervisor should be on duty whenever
the cannery is in operation. The
person in charge must have a thorough
knowledge of every aspect of
food processing.
The Food and Drug Administration
requires that a “certified registered
canner” be in attendance only when
low-acid foods are processed to be
sold. An FDA-approved course is offered
by the National Canners Association
for commercial cannery
personnel in various sections of the
country. The cost would involve a
registration fee of approximately $125
plus expenses. At present, the course
content is geared chiefly toward industry.
A shift to a more practical
approach would be of greater help
to community cannery personnel.
Cannery supervisors and attendants
can participate in food preservation
classes and demonstrations provided
by the Extension Service. When canneries
376
are equipped with commercial
food preservation centers, representatives
of the manufacturing companies
are available for technical information
to the cannery staff. Manufacturers
may also provide the cannery
with a complete operations manual,
processing charts, and recipes.
Cannery supervisors will benefit
by employing people to work at the
cannery who can provide or learn
such skills as:
Bookkeeping/accounting—to keep
records of input and outflow of goods
and money; to pay bills.
Management—to oversee the flow
of food through the center in an efficient
manner for smooth operation of
the plant.
Maintenance and repair—to maintain
equipment and housing in operational
condition.
Purchasing/supply—to ensure a
supply of materials such as jars and
lids.
Sales—to manage sales of surplus
retail products if these are processed
at the plant.
Public relations—to advertise and
promote knowledge of canning centers;
to handle complaints and problems
of patrons.
Technical—to provide detailed information
on processing techniques,
food, nutrition, and gardening.
A form of recordkeeping on all
foods processed at the plant is essential.
This kind of information would
include such data as name of person
doing the processing, the date, specific
food, number of jars, method
of processing, time in and time out,
and an identification number for
foods processed for sale by the
cannery.
Canning centers may be incorporated
as independent nonprofit cooperatives
with a board of directors
as the policymaking body. By being
organized in conformity with the traditional
farmers’ cooperative structure,
the centers receive special tax
considerations. Incorporation on a
nonprofit basis is a requirement of
many funding sources. The cooperative
structure also lends itself to a
tighter knit organization, with members
feeling they are part of the
organization, responsible for its affairs,
and willing to pitch in and help
if there is some work that needs a
few extra hands.
The community cannery should
have general liability insurance to
cover injuries sustained by the workers
or persons using the canning center.
Products liability insurance is
unnecessary for the cannery operated
solely to provide a service to the community.
For the cannery that sells
commercially, products liability insurance
should be obtained.
Sealer in a community cannery.
A community cannery should be
available to all people interested in
preserving food. Ideally, canneries are
open during daytime and evening
hours. Weekend hours are a possibility.
When canneries are limited to
processing vegetables and fruits, at
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least 6 months of potential operation
are lost in certain sections of the
country. If at all possible, canneries
should be operated to process a wider
range of foods such as jams, jellies,
pickles, preserves, meat, fish, poultry.
William E. Carnahan Tomato juice being processed at a community
cannery. Since cannery is operated
by State of Virginia, only charge
is for cans used.
A processing fee is usually set for
use of the canning equipment, ranging
from 5¢ to 10¢ for pints to 10¢ to
15¢ for quarts. These prices do not
include the cost of jar, lid, screw
band, or any canning supplies such as
salt, vinegar, sugar, spices that may
be sold at wholesale prices at the
cannery. An additional charge of 50¢
per hour is common for the use of a
pulper-juicer and steam-jacketed kettle.
It may be a financial hardship for
some low-income families to meet
these costs, but they can be given the
opportunity to exchange work time
at the cannery for payment. Families
of limited resources might leave off
a percentage of their processed high-acid
foods to be sold by the cannery.
Sponsoring agencies may apply for
grants, such as might be available
from Title XX of the Social Security
Act, in an effort to subsidize canning
costs for low-income families.
To date, no community canneries
are completely economically self-sufficient,
so far as we know. There
are centers in the South which do
enough community canning to pay
for all their expenses except salaries.
To become self-supportive, some canneries
are now developing specialty
products to be sold commercially.
Organic-health food distributorships
and food co-ops are often a good
market for community cannery processed
foods.
The future of community canneries
depends on continued interest in
home gardening and food preservation,
and concern for proper nutrition.
Undoubtedly, the cost of food in the
marketplace will also be a contributing
factor.
Consumers frequently have questions
regarding home food preservation
practices. Below are some
questions commonly asked, and the
answers. They concern canning fruits,
vegetables, pickles, and jellies, and
freezing fruits and vegetables.
Why is open-kettle canning not recommended?
In open-kettle canning, food is
cooked in an ordinary kettle, then
packed into hot jars and sealed. The
food is not processed after packing
in the jars.
Open-kettle canning is unsafe because
temperatures reached are not
high enough to destroy all the spoilage
organisms that may be in low-acid
foods, such as meat and vegetables,
other than tomatoes.
Spoilage bacteria may also enter
the food when it is transferred from
kettle to jar, making it undesirable
as well to can other foods such as
fruits, pickles, preserves, and jams
by this method.
Why is oven canning unsafe?
Jars may explode, causing personal
injury or damage to the oven. Also,
temperatures obtained in the oven are
not high enough to insure adequate
destruction of spoilage organisms in
low-acid foods.
Times specified for boiling-water-bath
processing of foods do not apply
to oven processing since the rate of
heat penetration would be different
in the oven and the products could
easily be underprocessed.
Should jars and lids be sterilized before canning?
No, not when the boiling-water-bath
or pressure-canner method is
used, because the containers and lids
are sterilized during processing. But
be sure jars and lids are clean.
Why is no liquid added when tomatoes are canned?
Because tomatoes provide their
own juice if pressed gently when
packed raw, or when heated before
packing hot into jars.
Is it safe to add celery, green pepper, and onion to tomatoes when canning them?
No. Adding other vegetables lowers
the acidity of tomatoes. Acidity helps
protect against the growth of botulinum
bacteria, which can produce a
fatal toxin in canned foods. Specific
recipes, times, and temperatures determined
scientifically for vegetable
mixtures need to be used for their
safe canning.
Why is headspace important in canning?
Headspace—the distance between
the surface of food and the underside
of the lid—allows for expansion of
solids or bubbling up of liquid during
processing. If headspace is not adequate,
some food in the container will
be forced out, leaving food particles
or sirup on the sealing surface and
preventing a seal.
When too much headspace is allowed,
some air may remain in the
jar after processing, causing food at
the top of the jar to darken.
What causes jars to break in a canner?
Breakage can occur for several reasons:
(1) Using commercial food jars
rather than jars manufactured for
home canning, (2) Using jars that
have hairline cracks, (3) Putting jars
directly on bottom of canner instead
379
of on a rack, (4) Putting hot food in
cold jars, or (5) Putting jars of raw
or unheated food directly into boiling
water in the canner, rather than into
hot water (sudden change in temperature—too
wide a margin between
temperature of filled jars and water
in canner before processing).
What causes liquid to be lost from jars during processing?
Loss of liquid may be due to packing
jars too full. Headspace must be
allowed between the top of the food
and lid as specified in the instructions
for each food. Food expands
when processed, so headspace must
be adequate or liquid will be forced
out of the jar.
Liquid may be lost if the canner’s
pressure fluctuates during processing.
Lowering the pressure too suddenly
after processing may also cause liquid
to be lost. Pressure canner should be
removed from the heat and allowed
to cool normally at room temperature.
If liquid is lost from jars during processing, can more be added to fill them again?
No, because if the jar is opened
and liquid added, this would allow
bacteria to enter the jar and you
would need to process again.
Loss of liquid does not cause food
to spoil, though food not covered by
the liquid may darken.
Why does fruit sometimes float in the jar after canning?
Fruit may float because it is packed
too loosely, sirup is too heavy, or
because some air remains in tissues
of the fruit after heating and processing.
How do you test the seal on home-canned foods?
After jars have cooled, check two-piece
lids by pressing the center of
the flat metal lid; if lid is down and
will not move, jar is sealed.
For porcelain-lined caps, check seal
by turning each jar partly over in
your hands. If no leakage occurs, the
jar is sealed.
What causes lids not to seal?
If food has not been sufficiently
heated, a vacuum may not be drawn
on the jar of food and the lid will
fail to seal. Presence of food particles
or sirup on the jar rim could also
prevent obtaining an airtight seal.
Each jar rim should be wiped clean
of all food and sirup before putting
the sealing lid in place.
If food has been packed too tightly
in the jars or if sufficient headspace
has not been allowed, expansion of
the food during heating could force
sirup or food out of the jar, thus
causing poor contact between the lid
and jar.
Why should flat metal disks and rubber rings be used only once?
Depressions in the rubber compound
made when the lid or ring
was first used can prevent obtaining
an airtight seal if used a second time.
Why should metal bands be removed after jars have cooled?
If bands are not removed soon after
cooling, moisture between the ring
and jar may cause the ring to rust,
thus making later removal of the
bands difficult. The band is no longer
necessary after the jar has cooled
because the seal has been provided
by the flat metal lid with sealing compound
and the vacuum created during
cooling.
What causes canned foods to change color?
Darkening of food at the top of
the jar may be caused by oxidation
due to air in the jar, or by too little
heating or processing so that enzymes
are not destroyed. Overprocessing
may cause discoloration of foods
throughout the jar.
Pink and blue colors sometimes
seen in canned pears, apples, and
peaches are caused by chemical
changes in the fruit coloring matter.
380
Iron and copper from cooking
utensils or from water in some areas
may cause brown, black, and gray
colors in some foods.
Why do undersides of metal lids sometimes discolor?
Natural compounds in some foods,
particularly acids, corrode metal and
make a dark deposit on the underside
of jar lids. This deposit on lids of
sealed, properly processed canned
foods is harmless.
Is it safe to use canned foods which have been frozen as the result of storing them in an unheated storage area?
Freezing does not cause the food to
spoil unless the seal is damaged or
the jar broken. If the jar is no longer
sealed, the food may still be safe to
eat if the jar is not broken and the
food is still frozen and has not been
subjected to thawing and refreezing.
Remove the frozen canned food
from jars as carefully as possible. The
food may need to thaw slightly to
ease its removal from jars, but it
should be left in as large blocks as
can be removed through the jar opening.
Examine jars for breaks and hairline
cracks. If any are found, discard
food from those jars. If no cracks are
found, food may be transferred from
jars into freezer bags or containers
and stored in the freezer, or it may be
kept in the refrigerator for use within
a day or two.
Home-canned foods which have
been frozen may be less palatable
due to texture changes than properly
stored canned foods. Do not recan
home-canned foods which have been
frozen.
How do you protect canned foods against freezing?
Wrap the jars in paper or cover
them with blankets. However, if the
storage area temperature is expected
to be below freezing (32° F) for more
than a day or two, move the food to a
warmer storage area.
What does mold on canned food indicate?
It means the jar has not sealed and
the food is spoiled. Even if mold appears
to be only on the surface, discard
all food in the container because
parts of the mold may not be visible
in the food.
Is it safe to can foods without salt?
Yes. Salt is used for flavor only in
canned vegetables and is not necessary
for safe processing. Since the
characteristic flavor and texture of
pickled vegetables depend on salt, do
not omit this ingredient from recipes
for pickles and relishes.
What kind of salt should be used in pickling? Why?
Use pure granulated salt. Uniodized
table salt can be used, but materials
added to the salt to prevent caking
may make the brine cloudy. Do not
use iodized table salt because it may
darken pickles.
What type of vinegar should be used for making pickles? Can it be diluted?
Use cider or white distilled vinegar
of 4% to 6% acidity (40 to 60 grain).
Do not use vinegar of unknown acidity.
Do not dilute vinegar unless the
recipe so specifies. If a less sour
product is preferred, add sugar rather
than decrease vinegar.
Why should pickles be processed in a boiling-water bath?
Pickles require heat treatment to
destroy organisms that cause spoilage,
and to inactivate enzymes that may
affect flavor, color, and texture.
Heat processing in a boiling-water
bath is recommended for all pickle
products. There is always danger of
spoilage organisms entering the food
when it is transferred from kettle to
jar. This is true even when the utmost
caution is observed and is the reason
381
open-kettle canning is not recommended.
Why should plastic containers not be used when brining pickles?
Vegetables being pickled undergo
physical as well as chemical changes
during brining or fermentation. As
a result of these changes, the plastic
may be affected, causing undesirable
compounds to be formed or leached
from the plastic.
For fermenting or brining pickles,
use a crock or stone jar, unchipped
enamel-lined pan, or large glass jar,
bowl, or casserole.
What causes pickles to be hollow?
Hollowness in pickles generally results
from poorly developed cucumbers,
holding cucumbers too long
before pickling, too rapid fermentation,
too strong or too weak a brine
during fermentation.
What causes jelly to be too soft?
Too much juice in the mixture, too
little sugar, mixture not acid enough
(overripe fruit), or making too big a
batch at one time.
What makes jelly tough?
Mixture was cooked too long to
reach jellying stage because too little
sugar was used in proportion to the
pectin and acid in the juice.
What makes crystals form in jelly?
Crystals throughout the jelly may
be caused by too much sugar in the
jelly mixture, or cooking the mixture
too little, too slowly, or too long.
Crystals on top of jelly that has been
opened and allowed to stand are due
to evaporation of liquid.
Tartrate crystals in grape jelly may
occur if juice has not been allowed
to stand overnight and then strained
through a double thickness of cheesecloth
before preparing jelly.
Is a one-door refrigerator-freezer combination suitable for freezing and storage of frozen fruits and vegetables?
It may be difficult to obtain the
recommended temperature of 0° F or
below for freezing and storing foods
in this style freezer without freezing
food in the refrigerator part as well.
Recommended storage times are
severely reduced if a freezer does not
maintain 0° F or below. If freezer
temperatures are above 10°, do not
store frozen food for more than several
weeks.
Can containers for commercial foods, such as cottage cheese, margarine, milk, yogurt, ice cream, or sour cream, be used for freezing fruits and vegetables?
Waxed cardboard cartons which
previously contained dairy products
are not sufficiently moisture-vapor-resistant
to use for packaging foods
to be frozen.
Plastic commercial-food containers
are suitable if they can be tightly
sealed and do not become brittle and
crack at low temperatures, thus exposing
the food to the air.
Can citric acid or lemon juice be used to help prevent fruit from turning dark during freezer storage?
Although these products can be
used as anti-darkening agents, neither
is as effective as ascorbic acid. Often
the quantity of citric acid or lemon
juice needed to prevent darkening is
so large that natural flavors are
masked or the fruit becomes too sour.
Why is it necessary to wash and blanch vegetables before they are frozen?
Washing removes dirt and some of
the bacteria from vegetables. Freezing
inhibits the growth of bacteria,
but does not kill them. Thus it’s important
that the food, as well as all
surfaces it touches, be kept clean so
that the number of bacteria on the
food is held to a minimum. Bacteria
can grow on food if the temperature
rises during freezer storage, and when
food is thawed.
382
Except for green peppers and mature
onions, vegetables must be
blanched to destroy enzymes which
could cause undesirable changes in
flavor, texture, and color during
freezer storage.
Why can green peppers and mature onions be frozen without blanching?
Unlike other vegetables, green peppers
and onions do not lose quality
during freezer storage if their enzymes
are not destroyed by blanching before
freezing.
Green peppers frozen without heating
are better suited for use in uncooked
foods than are blanched peppers.
Some of the characteristic flavor
of onions is lost if this vegetable is
blanched before freezing.
Why is corn which is frozen on-the-cob blanched for longer times than cut corn?
Longer blanching of corn frozen on-the-cob
is necessary so that enzymes
present in the cob will be destroyed.
Otherwise, enzymes in the unheated
cob can cause undesirable flavor
changes in the corn kernels.
Corn frozen off-the-cob needs only
to be blanched just enough to destroy
enzymes in the kernels.
Can vegetables be blanched by steaming instead of by heating in boiling water?
The following vegetables may be
heated in steam: broccoli, mushrooms,
pumpkin, winter squash, and sweet-potatoes.
To steam these vegetables, put 1
to 2 inches of water in a large kettle;
bring water to a boil. Add a basket
containing a single layer of prepared
vegetable; keep the basket at least 1
inch above the water. Cover kettle
and start timing.
Steam broccoli 3 minutes; sliced
mushrooms, 3 minutes; whole mushrooms
(less than 1-inch diameter), 5
minutes. Steam pumpkin, winter
squash, or sweet-potatoes until tender.
Is it necessary to make an adjustment in blanching times for vegetables at altitudes above sea level?
At altitudes 5,000 feet or more
above sea level, heat vegetables 1
minute longer than the time given in
directions for the vegetable being
blanched.
What can be done to prevent food from thawing if the freezer should stop running?
Never open the freezer unnecessarily.
A fully-loaded freezer will
usually remain cold enough to keep
food frozen for 2 days if the door is
not opened; a half-loaded freezer may
not stay cold enough more than a
day.
If power cannot be restored or the
freezer cannot be fixed before the
food would start to thaw, use dry
ice. If dry ice is obtained shortly
after the failure has occurred and
the freezer is fully loaded, 25 pounds
of dry ice should keep a 10-cubic-foot
freezer at temperatures below
freezing for 3 to 4 days; if freezer is
less than half-full, for 2 to 3 days.
Place dry ice on boards or heavy
cardboard on top of the packages of
food. Handle dry ice carefully—never
with your bare hands. Wear gloves
to prevent burns.
Another alternative is to move food
to a neighbor’s freezer or to a freezer
locker plant where space can be
rented.
Can vegetables and fruits which have thawed be refrozen?
Frozen foods that have thawed may
be safely refrozen if they still contain
ice crystals or if they are still cold—about
40° F—and have been held no
longer than 1 or 2 days at refrigerator
temperatures (32° to 40°) after thawing.
Since thawing and refreezing reduces
the quality of fruits and vegetables,
use refrozen foods as soon as
possible to save as much of their eating
quality as you can.
Acid food—Food with a pH of 4.6 or
below. An acid food can be safely
processed in a boiling-water bath for
specified times. Includes most fruits,
tomatoes, and pickled vegetables.
Anaerobes—Bacteria capable of growing
without air, as in a sealed container
of canned food.
Blanching—Heating vegetables by immersion
in boiling water, steaming,
sauteing, or stewing to inactivate enzymes
capable of causing quality
changes in foods during freezer storage.
Boiling-water-bath Canner—A large kettle
with lid, rack, and cover; must
be deep enough to allow jars to be
covered with 1 to 2 inches of water
and still have additional height for
water to boil actively. Suitable for
processing acid foods.
Botulism—Food-borne illness caused
from eating canned foods containing
the toxin produced by Clostridium
botulinum, an anaerobic bacterium.
This organism can grow and produce
toxin in sealed jars of canned foods
that are improperly processed.
Canning—Preserving food in airtight
rigid containers. Micro-organisms are
destroyed by heat-processing containers
of food at the temperature and
time specified for each food. It is
essential to follow reliable canning
instructions exactly to insure a safe
canned product that is free from
botulism-causing bacteria and spoilage
organisms.
Cold Pack—Raw, unheated food packed
into canning containers and covered
with boiling sirup, juice, or water.
Dehydrator—A device which removes
moisture, a dryer.
Enzymes—Proteins involved in plant
growth processes including maturation
and ripening. Enzymes can cause loss
of quality in food if they remain active
during storage. They are destroyed
by canning, or by blanching vegetables
before freezing.
Freezer Burn—Small, white, dehydrated
areas which occur on improperly
wrapped frozen foods. This condition
is harmless, but if extensive can cause
food to become tough or lose flavor.
Freezing—Preserving food by storing at
low temperatures. The recommended
temperature for freezer storage is 0°
F or below.
Headspace—The space between the top
of food in a container and the container
lid or closure.
Hot Pack—Food heated in sirup, water
or steam, or juice, and packed hot
into canning jars.
Hydrator (Vegetable Crisper)—A drawer-like
section in refrigerators which protects
fresh fruits and vegetables from
drying out during refrigerator storage.
Low-acid Food—Food with pH above 4.6.
A low-acid food requires processing
at high temperature under pressure to
destroy micro-organisms and insure a
safe canned product. Includes all
vegetables except tomatoes.
Micro-organism—Includes bacteria,
molds, and yeasts, which when present
in food can cause spoilage and
even food poisoning. Therefore, they
must be destroyed in canning foods
or their growth prevented in freezing
and drying foods.
Moisture-vapor-proof—Packing materials
that prevent loss of moisture from
foods during freezer storage. Examples
include glass, rigid plastic, and metal
freezer containers.
Moisture-vapor-resistant—Packing materials
that protect foods from moisture
loss during freezer storage. Examples
include freezer wraps—paper, plastic,
or foil—plastic bags, waxed freezer
cartons.
Molds—Microscopic fungi which form
air-borne spores (seeds) that may
alight on food and grow into cottony
mats or fuzz. Some molds or their
end products may be harmful, and
moldy vegetables or fruit should not
be canned. Molds are destroyed by
proper canning, but they may develop
in leaky containers. Food from leaky
containers or any canned food showing
mold growth should be discarded
without tasting.
Open-kettle Canning—Procedure whereby
food is cooked in an ordinary kettle,
then packed into hot jars and sealed.
Jars of food receive no additional heat
processing. This is a dangerous practice
as spoilage organisms may enter
the jar during the transfer of food
from kettle to jar. In low-acid foods,
384
temperatures obtained are not hot
enough to insure destruction of all
spoilage organisms that may be present
in the food.
Pack—Designates how food is packed
into containers. Specifies the temperature
of food when packed into jars
for canning, or the method of sweetening
fruits for freezer packs.
Pectin—A substance occurring naturally
in many fruits which causes the juice
to thicken or gel after heating if the
proper proportions of sugar and acid
are present. Natural pectins are more
prevalent in underripe fruit than mature
or overripe fruit. Some fruits have
enough natural pectins to make high
quality jams and jellies. Others require
addition of commercial pectins which
are made from either citrus peel or
apples.
pH—Measure of acidity of a product.
The lower the pH the higher the
acidity.
Preserve—To maintain the quality of
food for consumption at a later time.
Accomplished by canning, freezing,
pickling, drying, or making jelly, jams,
or preserves.
Processing—Heating food in closed canning
jars to insure destruction of
micro-organisms so the canned food
will remain unspoiled and safe to eat.
Acid foods—such as fruits, tomatoes,
and pickles—and jams and preserves
are safely processed in a boiling-water-bath.
Low-acid vegetables (all vegetables
except tomatoes) require processing
at higher temperature by use
of a pressure canner or pressure
saucepan. Times required to insure
an adequate process are specified in
canning directions for each food.
Sirup Pack—Fruit is packed for freezing
in a sugar sirup made by dissolving
sugar in water.
Steam-pressure Canner—A large, heavy
metal pan having a tight-fitting cover
which is fitted with safety valve,
steam vent or petcock, and a gage—either
weighted or dial. Used for
processing low-acid foods under pressure
at high temperatures in order to
insure their safety.
Steam-pressure Saucepan—Smaller than
a canner. If equipped with a gage to
maintain pressure at 10 pounds, it is
suitable for processing food in pint
jars.
Sugar Pack—Sugar is added directly to
fruit and mixed gently to draw juice
from fruit before packing into freezer
containers.
Unsweetened Pack—Fruit packed for
freezing without any sweetening added.
It may be packed dry or covered with
water.
Footnotes
[1]Edmund A. Zottola is Extension Food
Microbiologist and Isabel D. Wolf is Extension
Specialist, Foods and Nutrition,
at the University of Minnesota, St. Paul.
[2]Gerald D. Kuhn is Professor, Food Science
Extension, and Louise W. Hamilton
is Professor, Foods & Nutrition Extension,
The Pennsylvania State University,
University Park.
[3]Ruth N. Klippstein is Professor, Division
of Nutritional Sciences, Cornell
University, Ithaca, N.Y.
[4]Frances Reasonover is Extension Food
and Nutrition Specialist, Texas A & M
University, College Station.
[5]Charlotte M. Dunn is Food and Nutrition
Specialist, University of Wisconsin-Extension,
Madison.
[6]Nadine Fortna Tope is Extension Specialist
in Food Conservation and Preparation,
North Carolina State University,
Raleigh.
[7]Carole Davis is a Supervisory Food
Technologist, Consumer and Food Economics
Institute, Agricultural Research
Service.
[8]These instructions are for green beans only. Procedures and processing times are specific for each vegetable. See USDA Home and Garden Bulletin No. 8, Home Canning of Fruits and Vegetables, for directions for canning other vegetables.
[9]These instructions are for peaches only. Procedures and processing times are specific for each fruit. See USDA Home and Garden Bulletin No. 8, Home Canning of Fruits and Vegetables, for directions for canning other fruits.
[10]Annetta Cook is a Food Technologist
in the Consumer and Food Economics
Institute, Agricultural Research Service.
[12]These instructions are for green peas only. Preparation procedures and blanching times are specific for each vegetable. See USDA Home and Garden Bulletin 10, Home Freezing of Fruits and Vegetables, for directions for freezing other vegetables.
[13]Catherine C. Sigman is Extension
Home Economist—Foods, University of
Georgia, Athens. Kirby Hayes is Professor,
Department of Food Science and
Nutrition, University of Massachusetts,
Amherst.
[14]Isabelle Downey is Home Economist-Food
Preservation, Cooperative Extension
Service, Auburn University, Auburn,
Ala.
[15]Philip Wagner is Proprietor, Boordy
Vineyards, Riderwood, Md., and author
of Grapes Into Wine. J. R. McGrew is
with the Agricultural Research Service,
Beltsville, Md.
[16]Dale E. Kirk is a Professor and Agricultural
Engineer at Oregon State University,
Corvallis. Carolyn A. Raab is
Extension Foods and Nutrition Specialist
at Oregon State.
[17]Ralph W. Johnston is Chief, Microbiology
Staff, Meat and Poultry Inspection
Program, Food Safety and Quality
Service.
[18]Anton S. Horn is Extension Horticulturist,
University of Idaho, Boise. Esther
H. Wilson is Extension Nutrition Specialist,
University of Idaho, Moscow.
[19]F. Aline Coffey is Foods and Nutrition
Specialist, Vermont Extension Service,
University of Vermont, Burlington. Roger
Sternberg is Project Coordinator, Bread
and Law Taskforce, Montpelier, Vt.
[20]Carole Davis and Annetta Cook are
Food Technologists with the Consumer
and Food Economics Institute, Agricultural
Research Service.
[21]Annetta Cook and Carole Davis are
Food Technologists with the Consumer
and Food Economics Institute, Agricultural
Research Service.
U.S. GOVERNMENT PRINTING OFFICE: 1978 O-278-050
Transcriber’s Notes
Silently corrected a few typos.
Retained publication information from the printed edition: this eBook is public-domain in the country of publication.
In the text versions only, text in italics is delimited by _underscores_.
Transcribed or tabulated some text within illustrations.