_by Ralph W. Johnston_[17]
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 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.
[Illustration: 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 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.