TECHNICAL PAPER #59
PRESERVATIONS OF FRUITS
CANNING AND FREEZING
Joel M. Jackson
William G. Schultz
1600 Wilson Boulevard, Suit 500
Arlington, Virginia 22209 USA
703/276-1800 . Fax: 703/243-1865
Understanding Home-Scale Preservation of
Fruits and Vegetables
Part I: Canning and Freezing
[C]1988, Volunteers in technical Assistance
This paper is one of a series published by Volunteers in
Assistance (VITA) to provide an introduction to specific
state-of-the-art technologies of interest to people in
countries. The papers are intended to be used as guidelines
help people choose technologies that are suitable to their
They are not intended to provide construction or
details. People are urged to contact VITA or a similar
organization for further information and technical
they find that a particular technology seems to meet their
The papers in the series were written, reviewed, and
almost entirely by VITA Volunteers technical experts on a
voluntary basis. Some 500 volunteers were involved in the
of the first 100 titles issued, contributing approximately
5,000 hours of their time. VITA staff included Margaret
project manager, Suzanne Brooks handling typesetting,
graphics, and James Butty as technical writer/editor.
The author of this paper, VITA Volunteer Eric P. Rusten, a
Peace Corps Volunteer to Kenya and Nepal, is a graduate
at Washington University in St. Louis, Missouri. The
are also VITA Volunteers. William G. Schultz is a mechanical
engineer and has specialities in food processing
George Rubin is a product developer with Dell Products
in New Jersey, having retired as manager of the Welch
Foods Inc. in Westfield, New York; Joel Jackson is a food
with Food Preservation Systems in Windsor, Maryland.
VITA is a private, nonprofit organization that supports
working on technical problems in developing countries. VITA
information and assistance aimed at helping individuals and
groups to select and implement technologies appropriate to
situations. VITA maintains an international Inquiry Service,
specialized documentation center, and a computerized roster
volunteer technical consultants; manages long-term field
and publishes a variety of technical manuals and papers.
Preserving the surplus food that is often available at
time helps ensure a continuous supply of food throughout the
year. There are several methods of food preservation,
canning, freezing, pickling, drying, and curing (smoking or
All these preservation methods aim to prevent or at least
slow down spoilage. Careful attention to the proper
preserving and storing also helps ensure that the food stays
nutritious and palatable as possible.
This paper, the first of a two-part series, discusses
of canning and freezing fruits and vegetables at home, for
use. The companion paper presents the principles of drying
curing. Guidelines are given to help readers select the best
possible method of preserving the produce they have
Drying, smoking, salting, and pickling have been used for
of years to keep food from spoiling. Canning or jarring to
preserve food is much more recent. It was first developed in
by Nicholas Appert, a French chef who learned that food
in sealed containers would keep for extended periods of
Appert, like his predecessors, did not know why food
spoiled or why their technique worked, this early method was
quite successful and has changed little since it was
Today, it is one of the most popular methods of preserving
In the early twentieth century, freezing became a popular
for short-term preservation of food, but its high cost has
it from becoming as common as canning in many parts of the
II. FOOD SPOILAGE
WHY FOODS SPOIL
The rotting of fruits and vegetables has four major causes.
of these--molds, yeasts, and bacteria--are microorganisms
in great numbers in the air, soil, and water. They are the
causes of food spoilage. Enzymes, the other major cause of
food spoilage, are complex chemical substances found in all
cells, including the skins and flesh of fresh fruits and
vegetables. All preservation methods are aimed at preventing
these four agents from acting upon the food being preserved.
Molds are fungi that grow in warm, moist food. As the mold
it slowly consumes the food matter and brings about changes
the character of the food. This promotes the growth of other
microorganisms, eventually leading to complete food
The ideal temperature for mold growth is between 10 and
But at temperatures of 90[degrees]C or more, all molds and
are destroyed, except for a few rare, heat-resistant
Yeasts are another type of fungi. They act upon starches and
sugars to produce alcohol and carbon dioxide in the process
fermentation. The ability of yeasts to bring about
makes them very valuable organisms for the production of
beer, and wine. But they can cause food to ferment even when
is not desired, making the food unfit for consumption. This
of food spoilage can be prevented by reducing the moisture
of the food and raising or lowering the temperature beyond
the point required for yeast growth.
Bacteria are microscopic organisms that exist almost
Some bacteria are beneficial in that they help in the
of certain foods. For example, cheeses are made by the
certain bacteria on milk. Yet others are harmful because
contribute to food spoilage or produce poisons that can
serious illness and even death when ingested.
Some spoilage-causing bacteria can be killed at the same
that destroy yeasts and molds. Others must be heated to
temperatures as high as 116[degrees]C (240[degrees]F) for as
long as 20 minutes.
Keep in mind that cooking time lengthened as altitude
Where food preservation is concerned, the most dangerous of
bacteria is the one that causes botulism, a disease that is
fatal. Botulism-causing bacteria are naturally found in the
They thrive at moderate temperatures between 21[degrees] and
and 120[degrees]F) and can be easily introduced into food
utensils, soiled hands, or polluted water.
Botulism-causing bacteria can be destroyed by heat at
above boiling, at least 116[degrees]C (240[degrees]F), for
up to 20 minutes.
This type of bacteria can survive, grow, and reproduce only
in moist environments at room temperature, and in the
air. These are the exact conditions present in cans or jars
food is preserved by the canning process.
Properly canned food should be safe from botulism poisoning,
since both the poison and bacterium are destroyed by boiling
15-20 minutes. But if canned food should ever smell bad when
opened, it should be discarded to avoid being eaten.
Enzymes are organic compounds classified as proteins. They
as chemical catalysts in the cells of plants and animals
and are essential for normal growth and development.
after a fruit or vegetable is picked, its enzymes slowly
functioning in their normal constructive way and start to
down the plant tissue. If this action is not slowed or
the produce will start to decompose and eventually spoil. It
therefore necessary to slow or stop the action of enzymes if
fruits and vegetables are to be preserved successfully.
Enzyme action requires specific environmental conditions within
the cell. These include narrow ranges of temperature,
and acidity. If any of these conditions is significantly
the action of the enzyme can be altered. For example, enzyme
action slows down at lower temperatures and increases at temperatures
slightly higher than normal. Some enzymes are destroyed
when plant tissue is heated above 54[degrees]C
(130[degrees]F). But many, including
some that contribute to browning of foods, may not be
at temperatures less than 90[degrees]C.
Besides temperature and moisture, two other factors affect
actions of food spoiling agents. The first is cleanliness,
act of working with food only under sanitary conditions.
involves cleaning all foods thoroughly before preserving
keeping hands and work area clean, and washing all equipment
in the preservation process in boiling water. If proper care
taken to keep everything very clean, food that is preserved
should keep for many months, remaining tasty and nutritious.
The second factor in controlling food spoiling agents is the
level of acidity of the food being preserved. Many of the
that bring about spoilage are very sensitive to acidity
and cannot live in highly acidic environments. These
agents can be controlled by increasing the acidity of the
Some fruits and vegetables are naturally acidic and
therefore are easier to preserve. Foods with the acidity
of 4.5 or higher are considered to be low in acid. Beans,
corn mushrooms, pumpkin, white potatoes, etc., are some
of common low-acid fruits and vegetables. On the other hand,
foods with acidity measure of below 4.5 are regarded as
acid content. Some examples of high acid fruits and vegetables
are lemons, grapefruits, oranges, tomatoes, pineapples, etc.
is important to remember that varieties of the same food
have different ratings, as will identical varieties grown
III. FOOD PRESERVATION METHODS
The major methods of fruit and vegetable preservation are
pickling, drying, freezing, and curing (smoking or salting).
Whatever method of preservation you choose, keep in mind
that preserved food is only the next-best alternative to
food, not a replacement. Whenever a fruit or vegetable is
some of the food's nutritional value is lost, along with
some of its natural flavor, color, and aroma. For this
only the freshest and best quality fruits and vegetables
be used for preservation.
Canning is practiced in many parts of the world. Even though
seems quite complicated at first, canning is easy once a
becomes familiar with the process.
Canning uses heat to bring about sterilization and the
of air for preserving fruits and vegetables. Heat
destroys the microorganisms that cause spoilage or poisoning
food. Exclusion of air forces air out of the food, thus
an airtight seal. Two methods are used to sterilize the
water bath, and the pressure cooker. In the water bath
the jars of food are submerged in water in a large kettle
allowed to boil for a specified period of time. The pressure
cooker method, which must be used for safe handling of low
foods, uses a pressure canner instead of a kettle to achieve
higher temperatures that are necessary.
After freezing, canning is the most expensive home method of
preserving fruits and vegetables. However, it is one of the
methods of preserving products that are to be stored for
periods of time. Most of the expense involved in canning is
initial investment in canning jars and other equipment that
not be on hand in the home. Once all of the materials are
canning becomes much less expensive, since the costs are
over time. When compared to the cost of fruits and
purchased during off-season or those commercially canned,
cost of home canning often is inexpensive.
The Principles of Canning
Only fresh, undamaged fruits and vegetables should be
for canning. They should be carefully trimmed, cleaned, and
into pieces of the desired size for preserving. The food is
packed into jars either hot (hot packing) or raw (cold
The method used depends on the type of fruit or vegetable
preserved and the recipe being followed.
Fruits and vegetables that are fairly delicate in nature are
often packed raw because they tend to keep their shape
with this method. After being carefully but firmly packed
the jars, some type of boiling liquid, specified by the
being followed, is poured over the produce. Firmer fruits
most vegetables are often pre-cooked before packing
since they take up less space in the jars after being
Usually, hot-packed produce has a shorter processing time
cold-packed produce since the food has already been cooked.
time required for pressure canning is not shortened much at
Regardless of which packing method is used, it is important
leave a small amount of air space--about one to three
deep--between the food and the jar lid. It is also advisable
cover the food completely with liquid to prevent its
the air, which may discolor it.
Water Bath Process. If the cold pack, or water-bath, canning
method is being used, the packed jars, with their tops put
place but not sealed tightly, are placed on a shallow rack
large pan filled with warm water (never place cool jars in
water or they may break). Add enough water to completely
cover the jars of food by at least three to five
the water in the water-bath boils, any air in the jars or
will be expelled. This helps to create a vacuum, thus
the jars to seal tightly.
After the appropriate processing time, the jars are allowed
cool for a minute or two in the water. They are then lifted
of the hot water and dipped into cold water. Dipping secures
seal by increasing the vacuum.
When the jars are completely cool, they are labeled with the
of the produce and the date canned, and carefully stored
a cool (between 4 and 21[degrees]C or between 40 and
70[degrees]F), dark place to
retard the loss of nutrients.
Pressure Process. To process low acid fruits and most
it is necessary to use a pressure canner instead of a
canner. Read carefully any canning instructions provided by
manufacturer of the pressure canner being used. First, pour
into the pressure canner to a depth of about four
Next, carefully place the jars on the rack and seal the
canner. Heat the pressure canner on a cookstove for several
until steam leaves the vent at the top of the pressure
canner's cover. Then fix the weighted gauge over the vent.
After the appropriate cooking time for the food being
let the pressure canner cool until the inside pressure,
by the gauge, falls to zero. Then gently raise the gauge
off the vent to release excess steam from the pressure
Open the pressure canner by lifting the lid away from you so
you will not be burned by any remaining hot steam.
Remove the jars, and let them cool until they can be
Then carefully place them in cold water to complete the
process. Finally, label the jars and store as described
Equipment and Materials Required
Much of the equipment required to can fruits and vegetables
already be present in many homes. The amount of equipment to
purchased depends upon how much canning will be done and
fruits and vegetables will be preserved. The following is a
of basic equipment often needed to can fruits and
o A large tall
cooking pot for water-bath canning (See Figure 1).
The pot should be either stainless steel or
when they come
should also be
7.5 to 12.5 centimeters
the jars used
o A pressure
cooker or pressure canner (see Figure 2) for
low-acid foods. This should be large enough to
hold at least
can be used,
since it is
o Jars that are
in very good condition with tight-fitting
lids and seals.
o Cheese cloth or
a wire basket to hold food for straining
(dunking fruits and vegetables in boiling
exposing them to steam).
o Large spoons
and a ladle, made of wood or stainless steel,
and a selection
of knives and smaller cooking pots.
o A wide-mouthed
funnel for filling jars.
o Something with
which to lift jars out of the cooking pot
canner (special tongs may sometimes be available).
spoons and cups, and a timer.
In addition to this equipment, some type of cookstove will
needed to heat the water-bath canning pot or pressure
The Pressure Canner. The most expensive piece of equipment
from the cookstove is the pressure cooker or pressure
Whether or not this is needed will depend upon the acidity
fruits or vegetables to be canned. The pressure cooker is
for low-acid foods (all vegetables except tomatoes), but
it is not necessary if only high-acid foods such as tomatoes
most fruits are to be canned.
The pressure canner is the only type of cooking device that
destroy the bacteria spores responsible for producing
poison. The pressure canner pressurizes the boiling water,
the temperature of the steam inside to reach temperatures as
high as 121[degrees]C (250[degrees]F). Because of the high
pressure and temperature
produced by the pressure canner, it is very important to
follow the manufacturer's instructions carefully and keep
vent and safety valve unclogged and clean.
The Jars. Special care also needs to be taken in the
canning jars, since faulty jars may lead to spoilage of the
food. If possible, jars made specifically for home canning
should be used. The cost of the jars could be expensive, but
averaged over the many years that they can be used, their
cost becomes much lower. Most beginning canners may find it
necessary to start with a relatively small number of jars
first year and then add more jars each successive year. This
help reduce initial expense and make the first year's work a
Most canning experts advise against using jars that have
been used to store commercially canned produce. According
to these experts, such jars are designed to be used only
are not as sturdy or well made as jars manufactured
for home canning. In addition, commercial canning jars are
difficult to reseal once the jars have been opened. This
contamination and spoilage of the canned produce. Commercial
can be used for some applications, such as the canning of
and jellies, since they are used only as containers and do
play a critical role in the preservation process.
Three general types of jars are made specifically for home
a jar with porcelain-lined zinc cap and rubber ring closure;
a jar with a screw band and self-sealing lid; and a jar with
glass lid, rubber ring, and wire-clamp fastener. Examples of
these jars are shown in Figure 3. All canning jars have the
of being usable over and over again. Only the rubber
seal or self-sealing lid needs to be replaced after each
Canning is not overly complicated, but it requires careful
and execution if it is to be successful. Since it is best to
can only fresh, undamaged fruits and vegetables, canning
be done during peak harvest times, when a sufficient supply
produce is available. The number of workers and the amount
time needed to process the produce depend upon the quantity
fruits and vegetables that can be processed. Generally, home
canning can be accomplished by as few as one or two people,
each canning session may last from four hours to all day.
time also depends upon the number of jars of produce that
processed by either the pressure canner or the water-bath
at each heating; a larger canner permits the processing of
jars at one time. To keep the time required for canning to a
minimum, it is important to make sure that all the equipment
materials needed are clean and ready for use.
Remember that water-bath canning time lengthens as altitude
Therefore it is important to adjust cooking time with
Canning is second only to freezing in terms of the quantity
commercial energy required, but this amount is relatively
Although it is possible to heat both the pressure canner and
water-bath canner over a wood fire, it is much more
use kerosene, gas, or electricity, and the amount of heat
is much more easily controlled.
There are essentially three steps in the canning process
require energy use. The first is the cleaning of the canning
equipment, jars, lids, and seals with scalding water.
on the recipe being followed, some fruits and vegetables
also need to be blanched (dipped in boiling water for a
period of time to retard or stop the destructive action of
or precooked before they can be processed. This is the
second step of the canning process that requires the use of
Finally, all produce must be processed in either a pressure
canner or water-bath canner. The quantity of energy used in
of these steps depends primarily upon the amount of produce
To determine whether canning is an economically viable
preserving produce for a specific family, it is necessary to
compare the costs and benefits of canning against other
For example, it is important to compare the costs of canned
produce with the average yearly cost of fresh produce. When
doing this, it is also helpful to spread the cost of the
jars, and other utensils over several years, not just the
year of purchase or for a single year of canning. Most of
equipment can be used year after year, and usually for more
just canning. This makes canning less expensive.
Generally, fruits and vegetables are least expensive and
readily available during peak harvest, which is not only the
time to eat fresh produce, but the best time to preserve it
later use. Preserved produce has its greatest value during
off-season when fresh fruits and vegetables are either not
available or are very expensive.
Another important consideration is the cost involved in the
of fruits and vegetables due to spoilage. People who have
often harvest more than they can either consume or sell.
Preserving this surplus is likely to be more economical than
letting it spoil. In addition, having a variety of canned
and vegetables on hand for year-round consumption adds
to meals, and improves a family's diet. The economic advantage
of a better diet may be difficult to estimate, but it should
obvious to everyone.
It is also important to compare the cost of home-canned
to that of commercially canned produce. When making this
it is important to consider not only the price difference
but also the probable difference in quality. Home-canned
is often of higher quality and superior flavor than
canned food. In addition, if you are considering home-scale
you need to weigh the costs and benefits of this method
against other preservation methods for home use.
Finally, you should consider the value of your time. Is
your own food the best way to spend your time, especially if
must also work full time at a job, in the fields, or
You may not have choice--preserving your own foods may be
only way to assure an adequate diet for your family in the
season. But your time is important, and it should be
Advantages and Disadvantages
The advantages and disadvantages of home-scale canning
upon the type of produce being preserved, the conditions of
specific locality, and the skills and resources of the
will be doing the work. There are some general points,
that should be considered. Canning, like all preservation
prevents the unnecessary loss of food due to spoilage. This
enables people to eat specific fruits and vegetables
thus improving the character and quality of their diets.
produce is easy to store, and it also retains much of the
flavor, color, and nutritional value of the fruit or
One of the biggest advantages of canning over other
methods is that at meal time canned produce is quick and
prepare since it has already been cleaned, cut, and in many
cooked. Properly canned food also has a shelf life ranging
six months to several years, depending on the type of food.
On the other hand, canned produce, like all preserved
suffers some loss of vitamins and other nutrients. But the
of only a small portion of the nutritional value of a food
little consequence when compared to not having any of the
nutrients available at all.
The biggest disadvantage of canning is the high initial cost
all the equipment needed to start a home-scale canning
This may prohibit some people from using this technique. An
disadvantage for some people may be the difficulty of
acquiring the pressure cooker or pressure canner that is
to can low-acid foods. The special jars needed to can
the home-scale may also be difficult to acquire in some
The energy demands of canning may also prove to be a
to some, and therefore a less energy-intensive preservation
may need to be chosen.
Little more than cleaning is needed to maintain a good
operation, but the value of this cannot be overstressed. The
cleaner the equipment, jars, produce, kitchen, and work surfaces,
the better the results. The old saying, "An ounce of
is worth a pound of cure," is very appropriate for
Since the jars are one of the most important parts of the
canning process, they should be examined very carefully
being used. Any chipped or damaged jars should be discarded
with any imperfect rubber rings or lids. A defective jar,
seal could lead to contamination and spoilage, and even
poisoning. If a pressure canner is used, it is very
follow the maintenance instructions provided by the
Variations and Alternatives to Home-Scale Canning
One possible way to overcome the problems of high initial
to establish a cooperative canning center. Through a
effort, a group of people could combine their financial
to purchase a large water-bath canner and pressure canner,
well as other utensils. This may result in significant
Also, if enough people are involved in the cooperative
center, the cost of the jars may be reduced by buying in
Communities that already have agricultural cooperatives will
probably have little difficulty getting such a community
center started. Before this type of cooperative can be
however, it is important to address some basic questions.
First, are there enough people in the community interested
canning fruits and vegetables? Second, is there a building
for such a cooperative to use? Since canning is generally a
seasonal activity, there is no need to have a
kitchen. Third, is there someone in the community with the
skills to supervise the activities of the cooperative and
the necessary financial records? If positive answers to
questions can be found, there is a good chance that a
canning kitchen could be established.
Freezing involves lowering the food temperature below the
point of water (0[degrees]C or 32[degrees]F). For the
initial freezing of
fruits or vegetables, it is important to lower the
of the produce to between -15[degrees]-20[degrees]C
(-5[degrees] -0[degrees]F) as quickly as possible.
For quicker freezing, fruits and vegetables should be
spread out individually on trays in the freezer so air can
freely. The more rapid the freezing process, the fresher
tasting the final product. Once the food is frozen, it
packaged and then stored at about -20[degrees]C
Generally, fruits and vegetables are each prepared
for freezing, but in all cases, only fresh, undamaged
should be selected for freezing.
Freezing fruits and vegetables requires equipment such as a
freezer or access to frozen food cooler, food containers
plastic boxes, heavy plastic bags), waxed paper boxes,
kettle, strainers, a timer, etc.
Fruits are usually not blanched or cooked before they are
to allow them to retain their garden-fresh flavor. Fruits
peaches are an exception to this rule because their peels
much easier to remove after blanching.
There are two basic ways to pack fruits. The first and
is the dry pack method: the fruit is just put whole or cut
peeled into containers and then placed in the freezer. In
cases, it is better if the fruit is allowed to freeze first
it is packed so that it will not stick together in the
The advantage of this packing method is that the fruit
can be used a little time.
The second way to pack fruits, and probably the preferable
for most fruits, is the wet pack method in which the fruit
packed along with some liquid, usually sweetened. For fruits
are naturally juicy, all that may be needed is to add some
The sugar not only sweetens the fruits but draws out their
juices, which results in the formation of a sweet syrup.
all the sugar is dissolved, the fruit can be packed and
Other fruits can be frozen after a cold sugar syrup is
over the packed fruit. Plain fruit juice and water can be
place of a sugar syrup if the extra sweetening is not
Vegetables, like fruits, are prepared for freezing by
cutting, and peeling. Unlike most fruits, however,
must be blanched in boiling water for a few moments and then
quickly dunked in very cold water. Blanching maintains
and slows enzyme activity. It also softens the vegetables,
them easier to pack. Before packing and freezing, they
thoroughly drained. If wet vegetables are placed in the
they stick together and frost will form in the container.
vegetables are packed in containers without adding anything
extra. This allows them to be used as if they were fresh
Care of Frozen Food
It is important to remember that unfrozen food should not be
piled together in the freezer. Instead it should be spread
along shelves so that it will freeze as quickly as possible.
packaged fruits and vegetables should be carefully labeled
the amount of produce, the name of the fruit or vegetable,
the date. Labeling makes it easier to identify the contents
each package. Finally, food stored in the freezer should be
so that the oldest food is eaten first. This will prevent
food from being held in the freezer for too long. Dating
ensures that the oldest frozen produce will be used first.
that frozen produce generally has a maximum storage life of
year. Longer storage will not make foods unfit for use, but
As a general rule, foods that have been completely thawed
not be refrozen because they may become sources of food
and because quality is reduced. More information about the
requirements for varieties of fruits and vegetables can be
found in many guide books on food preservation.
As noted, freezing is the simplest, quickest, and easiest
of preserving fruits and vegetables. Home-scale freezing can
easily be done by one person, although two or three people
course be involved. The fact that only small batches of
produce are frozen at any one time makes the job less
The amount of electricity required to operate a freezer
upon the model and age of the freezer, its usage, and the
temperature. Usually, a freezer is a fairly expensive piece
equipment to own. Energy use can be slightly reduced by
the freezer as full as possible (jugs of water can be used
occupy spaces not taken (up by food) and opening the door as
Freezers that keep frost from accumulating,
i.e., frost-free freezers, use more energy than
if the regular freezer is periodically defrosted.
The only other stage in the freezing process that uses
the blanching of vegetables. If the produce is well prepared
advance, energy use can be kept to a minimum.
The main expenses associated with freezing are the initial
of the freezer and the daily cost of the energy needed to
running. Both of these costs may equal the value of the time
saved in the preparation of the produce for freezing, along
the ease of preparing the frozen food for the table. If the
of the freezer and electricity run second to the value of
time and energy required to prepare produce for
the character of the preserved fruits and vegetables is of
concern, freezing may be the best method.
Finally, the Asian Institute of Technology in Bangkok,
has developed an experimental freezing unit that runs on
energy instead of electricity. At present, this system is
too large and expensive to be used in the home. It is
however, that inexpensive home-scale solar-powered freezers
be developed in the future.
Advantages and Disadvantages
The major advantage of frozen produce is that it retains
its original fresh flavor, color, and nutrients. It is also
and easy, requiring little preparation, and the final
superior to other produce preserved using other methods. On
other hand, the disadvantage is the cost involved in the
and operation of the freezer. Another disadvantage is having
deal with a freezer full of thawing food in the event of a
outage or freezer failure.
Except for cleaning the equipment used to prepare the
freezing, there is little regular maintenance. If the
not self-defrosting, it must be periodically defrosted.
is necessary for two reasons. First, as frost builds up it
takes up valuable space in the freezer that could have been
to freeze fruits and vegetables. Second, frost build-up
the cooling efficiency of the freezer. Regardless of what
freezer you own, it is important to follow maintenance
provided by the manufacturer of the freezer.
Alternatives to Home Freezing
In some situations, it may be possible to rent storage space
large commercial frozen food locker instead of buying a
This may be a good way for people to become familiar with
freezing method before actually committing themselves to an
piece of equipment. However, a disadvantage of renting
freezer space outside the home is the added difficulty of
to transport the prepared fruits and vegetables to the
and then bring them back home when they are needed.
IV. CHOOSING THE
PRESERVATION METHOD RIGHT FOR YOU
It is unlikely that only one of the four preservation
--canning, freezing, drying, or curing--would be the only
method. Therefore, a food preparation system should be
that matches your particular situation. Such a system
should consist of a combination of methods that are
for the different types of fruits and vegetables to be
It should also meet the available resources and the specific
needs of the individuals involved.
The two most dominant constraints affecting the type of
system that can be used are the availability of capital
and the cost and availability of a constant supply of
energy. These constraints essentially group the four
preservation methods into three primary systems:
1. Where commercial
energy and money are readily available,
comprising all four methods, can be used.
2. Where sufficient
energy but only a moderate supply of
available, system two, comprising canning, drying,
and curing, can
3. Where energy is
either lacking or very expensive, and
money is in
short, supply, system three, comprising
curing, can be used.
Secondary constraints are also important for determining
preservation method or methods can be used. For example, the
following questions should be addressed in deciding which of
four methods or system to use. The brief discussion
each question points out many factors that must be considered
before a decision can be reached.
o How long will the
food need to be preserved? If relatively
preservation is desired (six months to a year),
preparation is an important concern, then freezing
may be the best
o How much food
needs to be preserved? If only a relatively
small amount of
food needs to be preserved, then freezing
may be the best
choice. On the other hand, if quantities
to be preserved
are larger than available freezer space,
and/or smoking may be better choices.
o Are the proper
jars for canning available along with other
equipment? If so, and large quantities of food
need to be
preserved, then canning may be the best choice.
o What fruits and vegetables
need to be preserved? Some
vegetables respond better to specific preservation
methods. Some may
turn to mush if frozen; canning may
have the same
effect on others. To decide which method or
methods would be
most suitable for a specific vegetable,
it is best to
consult one of the books listed in the bibliography,
or seek help from
the government agricultural
office, a high
school, or a university.
o Is a special or
unique taste treat desired? If so, then
pickling may be better choices, since both are
used to make
o How much previous
experience with food preservation do you
have? If the
answer is little or no previous experience,
then maybe the
least complicated method should be tried
first. It is a
good idea to master this method before
advancing to more
complicated and difficult procedures.
o What is the
weather like during peak harvest time? If it
is sunny, dry, and
windy, then preserving with a solar
dryer may be a
good choice, provided it also meets all
o How many people
are available to help with a large quantity
of fruits and
vegetables? If only one or two family
members will be
involved in food preservation, it might be
best to select a
method, like freezing or curing, that can
be done in the
shortest amount of time with the fewest
number of people.
o Which preservation
method do you like best? Trying out
on a variety of fruits and vegetables
will enable you to
develop your own preferences. At this
point, it is
important to note that determining a preservation
careful consideration of many
make up a situation. In most cases, though,
there is a
significant amount of leeway open to the individual
in selecting the
appropriate preservation method.
Anderson, Jean. The Green Thumb Preserving Guide.
& Company, Inc., 1976.
The Complete Food Preservation Book.
Company, Inc., 1978.
Burch, Joan, and Burch, Monte. Home Canning and Preserving.
Reston Publishing Company, Inc., 1977.
Central Food Technological Research Institute. "Home-Scale
Preservation of Fruits and Vegetables."
Mysore, India: The
Wesley Press, 1981.
Hertzberg, Ruth; Vaughan, Beatrice; and Greene, Janet.
Brattleboro, Vermont: The Stephen Greene Press.
Kluger, Marilyn. Preserving Summer's Bounty. New York: M.
and Company, Inc.,
Levinson, Leonard Louis. The Complete Book of Pickles and
Relishes. New York: Hawthorn Books, Inc., 1965.
Schuler, Stanley, and Schuler, Elizabeth Meriwether.
the Fruits of the
Earth New York: The Dial Press, 1973.
Stoner, Carol Hupping, Editor. Stocking Up: How To Preserve
Foods You Grow,
Naturally. Emmaus, Pennsylvania: Rodale Press,
Groppe, Christine C., and York, George K. "Pickles,
Easy, and Safe Recipes." Leaflet No. 2275.
California: University of California, Division of
Etchells, John L., and Jones, Ivan D. "Preservation of
by Salting or
Brining." Farmers' Bulletin No. 1932.
U.S. Department of Agriculture, 1944.
Worgan, J.T. "Canning and Bottling as Methods of Food
Countries." Appropriate Technology. 4
Islam, Meherunnesa. Food Preservation in Bangladesh. Dacca,
Development Programme, UNICEF/DACCA, 1977.
Stiebeling, Jazel K. "Solar Food Preservation."
Institute of Technology, 1981.
U. S. Department of Agriculture. Human Nutrition Research
"Home Canning of Fruits and Vegetables."
U.S. Department of Agriculture, 1965.
VI. SUPPLIERS AND MANUFACTURERS
Dixie Canner Equipment Company
786 East Broad Street
P.O. Box 1348
Athens, Georgia 30601 USA
Food Preservation Systems
P. O. Box 188
New Windsor, Maryland 21776 USA
Freund Can Company
155 West 84th Street
Chicago, Illinois 60620 USA
(Cans and Sealers)
National Presto Industries
Eau Claire, Wisconsin 54701 USA
Refrigeration Engineering Corporation
P. O. Box 3-C
San Antonio, Texas 78217 USA