Resources for Home Food Freezing
National Center for Home Food Preservation
Freezing is the easiest, most convenient, and least time-consuming method of preserving foods.
The holiday seasons have a way of filling the freezer with leftovers. Adding these to the frozen
bounty of the past fall's harvest makes for tightly packed freezers. You can freeze almost any
foods and a list of foods and freezing instructions can be found here:
For a table of foods that don't freeze well see:
Freezing to fend off food spoilage
Food spoilage is caused by microorganisms, chemicals, and enzymes. Freezing foods to 0 degrees F. is recommended
for best quality.
Freezing stops the growth of microorganisms; however, it does not sterilize foods or destroy the
organisms that cause spoilage. A few organisms may die, but once thawed to warmer temperatures, these
organisms can quickly multiply.
Chemical changes affect quality or cause spoilage in frozen foods. One major chemical reaction is oxidation.
If air is left in contact with the frozen food oxidation will occur even in the freezer. An example is the
oxidation of fats, also called rancidity.
Enzymes are naturally present in foods and their activity can lead to the deterioration of food quality.
Enzymes present in animal foods, vegetables and fruit promote chemical reactions, such as ripening.
Freezing only slows the enzyme activity that takes place in foods. It does not halt these reactions
which continue after harvesting. Enzyme activity does not harm frozen meats or fish, but browning can
occur in fruits while they are being frozen or thawed.
Blanching vegetables before freezing inactivates the enzymes. During blanching, the vegetable is exposed
to boiling water or steam for a brief period. The vegetable is then rapidly cooled in ice water to prevent
cooking. Following the recommended times for blanching each vegetable is important. Over-blanching results
in a cooked product and loss of flavor, color, and nutrients. Under-blanching stimulates enzyme activity and
is worse than no blanching at all. See:
for blanching specifics.
Chemical Treatment of Fruits
Fruits may also be steamed or cooked before freezing, but are more commonly treated with ascorbic acid
to inactivate enzymes responsible for browning. See freezing recommendations for individual foods for
specific recommended ascorbic acid usage:
http://nchfp.uga.edu/how/freeze.html and http://nchfp.uga.edu/publications/uga/uga_freeze_fruit.pdf
for more information.
Packing and Packaging
Packing methods include dry packs, syrup packs, sugar packs, or possibly crushed or cooked packs.
Each has advantages and disadvantages. Pectin or artificial sweeteners are offered as options for
specific fruits. See freezing recommendations for individual foods for specific recommended packs:
for more information.
Good packaging will help prevent air from entering the container and moisture loss. Severe moisture loss,
or ice crystals evaporating from the surface of a product, produces freezer burn -- a grainy, brownish or
white surface where the tissues have become dry and tough. Freezer-burned food is likely to develop off
flavors, but it will not cause illness. Packaging in air-tight rigid containers or heavyweight, moisture-resistant
wrap will prevent freezer burn. See:
for more specifics. Follow directions on appropriate
packaging and labeling.
Textural changes during freezing
Freezing actually consists of freezing the water contained in the food. When the water freezes, it expands
and the ice crystals formed can cause the cell walls of the food to rupture. Consequently the texture of
the product will be much softer when the product thaws. Getting a food to a frozen state quickly helps
keep the size of the ice crystals small. Less damage to cell walls of foods will occur and the final texture
will be better. Keeping food frozen at 0 degrees F or lower will also minimize ice crystal growth that
results when food temperatures fluctuate (i.e., warm up and re-freeze) too much while in the freezer.
Never defrost foods on the kitchen counter, in a garage, basement, car, dishwasher or outdoors.
These methods can leave your foods unsafe to eat. There are three safe ways to defrost food: in the
refrigerator at 40 degrees Fahrenheit or lower, in the microwave immediately before cooking, or in
running cold water for very short periods of time. Foods thawed in the microwave or by the running cold
water method should be cooked thoroughly immediately after thawing occurs. See:
for specific instructions.
Using and Cooking Frozen Foods
If food is thawed in the refrigerator, it is safe to refreeze it without cooking, although
there will usually be a noticeable loss of quality due to the moisture lost through defrosting.
After cooking raw foods that were previously frozen, it is safe to freeze the cooked foods if
safe cooking procedures were followed.
If previously cooked foods are thawed in the refrigerator, you may refreeze the unused portion.
Again, there will be some quality loss from the additional freezing and thawing.
If you purchase previously frozen meat, poultry or fish at a retail store, you can refreeze
if it has been handled and transported properly, observing time limits for the Temperature
Danger Zone. (Do not keep perishable foods between 40 and 140 degrees F for more than 2
hours; limit time to 1 hour in very warm temperatures. Any times in the TDZ are combined to determine this limit.)
Foods thawed in the microwave or by the running cold water method should be cooked before refreezing.
Frozen fruits are often eaten without cooking. Many are best if eaten while they still contain
a few ice crystals. Vegetables may be cooked after thawing or while still frozen. Raw or cooked
meat, poultry or casseroles can be cooked or reheated from the frozen state. However, it will take
approximately one and a half times the usual cooking time for food that has been thawed.
Always cook foods to the recommended internal temperature using a food thermometer.
More tips and specifics on freezing foods can be found here:
Spanish language resources:
The original version of this page written by Brian A. Nummer, Ph.D., National Center for Home Food Preservation, 2004. Revised November 2012 by Elizabeth L. Andress, Ph.D. and Kasey Christian, M.Ed.
This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, U.S. Deparment of Agriculture, under Agreement No. 00-51110-9762.
Reviewed and slightly revised November 2012.
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