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 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.