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For Educators

 

Frequently Asked Freezing Questions

General

Can frozen food be stored in refrigerator-freezer combinations?
Is it necessary to leave headspace in packages to be frozen?
At what temperature should the freezer be maintained?
How long will food remain frozen if the power goes off?
Can food be refrozen if it has thawed?
What is freezer burn?
Does freezing improve the quality of food?
Does freezing kill germs?
How much food can be frozen at one time?
Will food spoil if the freezer temperature is above 0°F?
Will food spoil if it is stays frozen longer than the recommended storage time?
How can you be sure that your freezer is at 0°F or less?
Will it pay to buy a freezer?
Is a chest or upright freezer best?

Packaging Materials

What kind of packaging materials should be used for freezing?
Can aluminum foil be used as a freezer wrap?
Is wax paper a suitable freezer wrap?
Can bread wrappers be used for freezing?
Can zip-type bags be used for freezing?
Can milk or cottage cheese cartons be used for freezing foods?
Can glass jars be used for freezing?

Fruits

Is it safe to freeze fruits without sugar?
Can artificial sweeteners be used in place of sugar for freezing fruits?
How do you prevent fruit from turning brown during freezing?
Why are frozen fruits sometimes soft when thawed?

Vegetables

What is blanching?
Is it recommended to blanch vegetables before freezing?
How do you blanch vegetables?
Why is it necessary to cool vegetables after blanching?
What causes frost or ice crystals to appear on the surface of frozen vegetables such as broccoli?
Can I blanch in my microwave oven?
Can vegetables be fully cooked before freezing?
Does it matter how long vegetables are blanched?
Are frozen vegetables safe to eat if they are not blanched?
How can you prevent corn-on-the-cob from tasting "cobby"?
Should frozen vegetables be thawed before cooking?
Is it necessary to wash peas and lima beans before shelling?

Animal Products

Is it necessary to thaw meat or fish before cooking?
Can meat and poultry be thawed in the conventional oven?
Why is it important to chill meat or poultry before freezing?
Can stuffed turkey be frozen?


General

Can frozen food be stored in refrigerator-freezer combinations?
Refrigerator-freezer combinations can be used for storing frozen food if the freezer is a true freezer (will maintain 0°F or less) and not just a freezing compartment. A better quality product will be maintained at 0°F or less. If a freezing compartment is used, store food for only one to two weeks.

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Is it necessary to leave headspace in packages to be frozen?
With the exception of vegetables that pack loosely, such as broccoli and asparagus, leave adequate headspace between packed food and closure. This allows for expansion of food as it freezes.

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At what temperature should the freezer be maintained?
Freeze and store foods at 0°F or less.

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How long will food remain frozen if the power goes off?
Foods stay frozen longer if the freezer remains unopened, is full, is in a cool place and is well insulated. Usually food in a loaded freezer will stay frozen for two to four days, depending on its size. A half-filled freezer will keep food frozen only about 24 hours. Cover the freezer with blankets, keeping them away from the compressor, to help hold the cold.

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Can food be refrozen if it has thawed?
Foods can be refrozen if at least one ot these two conditions are met: 1) Foods have only partially thawed and still have ice crystals in the package; 2) The freezer temperature has remained at 40°F or below. Before using, check to see that color and odor of the food are good. Quality of the food will be lower.

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What is freezer burn?
It is dehydration or drying that occurs on the surface of a frozen product if it is improperly wrapped. The food is safe to eat but poorer quality. To prevent freezer burn, the package must be free of air and sealed airtight.

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Does freezing improve the quality of food?
Freezing does not improve the quality of the product. Frozen food is only as good as the quality of the fresh food. So, select only high quality products at optimum maturity and freshness.

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Does freezing kill germs?
Freezing does not kill all bacteria, yeasts and molds present in food, but it does prevent their multiplication if the food is held at 0°F or less. When thawed, the surviving organisms can multiply again.

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How much food can be frozen at one time?
Add only the amount that will freeze within 24 hours, which is usually two or three pounds of food per cubic foot of storage space. Overloading slows down the freezing rate. Also, foods that freeze too slowly may lose quality.

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Will food spoil if the freezer temperature is above 0°F?
Food may not spoil but the quality (color, flavor, and texture) will decrease. The higher the temperature, the faster quality will diminish.

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Will food spoil if it is stays frozen longer than the recommended storage time?
No. The recommended storage time is the time in which food should be used to insure maximum quality. Food stored longer than recommended time is safe but flavor, color and texture will continue to deteriorate.

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How can you be sure that your freezer is at 0°F or less?
Purchase a freezer thermometer, keep it in the freezer and check the temperature regularly.

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Will it pay to buy a freezer?
A freezer is usually more of a convenience than a saving. To make the best use of it, (1) keep the freezer full, (2) use and replace the food, do not just store it, and (3) use older food first.

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Is a chest or upright freezer best?
This depends on personal preference as well as available floor space. Generally speaking, the upright freezer is easier to organize and takes up less floor space. Chest freezers, however, are usually more economical to operate.

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Packaging Materials

What kind of packaging materials should be used for freezing?
Packaging materials must be moisture-vapor resistant; durable and leakproof; not become brittle and crack at low temperatures; resistant to oil, grease or water; protect foods from absorption of off-flavors or odors; easy to seal; and easy to mark. Good freezing materials include rigid containers made of aluminum, glass, plastic, tin or heavily waxed cardboard; bags and sheets of moisture-vapor resistant wraps; and laminated papers made specially for freezing.

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Can aluminum foil be used as a freezer wrap?
Heavy duty aluminum foil can be used as a freezer wrap. Because it can be torn or punctured easily it is wise to use an overwrap. Light weight (household) aluminum foil is not satisfactory for home freezing.

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Is wax paper a suitable freezer wrap?
No. Wax paper is not moisture-vapor resistant.

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Can bread wrappers be used for freezing?
No. Bread wrappers are not sufficiently moisture-vapor resistant to be used for freezing. A freezer-weight polyethylene bag should be used.

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Can zip-type bags be used for freezing?
Yes, if they have been designed for and their box marked for freezer use.

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Can milk or cottage cheese cartons be used for freezing foods?
Cardboard cartons for cottage cheese, ice cream or milk are not sufficiently moisture-vapor resistant to be suitable for long term freezer storage.

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Can glass jars be used for freezing?
Regular glass jars break easily at freezer temperatures. If using glass jars, choose wide-mouth dual purpose jars made for freezing and canning; these jars have been tempered to withstand extremes in temperatures. If standard canning jars (those with narrow mouths) are used, leave extra headspace in liquid packs (3/4-inch for pints; 11/2-inches for quarts) to allow for expansion of food during freezing and completely thaw food before removing it. Do not use regular canning jars for foods packed in water.

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Fruits

Is it safe to freeze fruits without sugar?
Yes; sugar is not used as a preservative but only to maintain flavor, color and texture.

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Can artificial sweeteners be used in place of sugar for freezing fruits?
Sugar substitutes can be used in place of sugar. Labels on the products give the equivalents to a standard amount of sugar. Follow the directions to determine the amount of sweetener needed. Artificial sweeteners give a sweet flavor but do not furnish beneficial effects of sugar, like thickness of syrup and color protection.

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How do you prevent fruit from turning brown during freezing?
There are several ways to prevent darkening of fruit; use pure ascorbic acid or ascorbic acid mixtures. Citric acid or lemon juice may sometimes be used but are not as effective as ascorbic acid. Some fruits which are to be cooked before serving may also be steamed to prevent browning.

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Why are frozen fruits sometimes soft when thawed?
If fruits are frozen slowly large ice crystals form and rupture cell walls causing a soft mushy product. For best results, quick freeze at -10°F and serve just as ice crystals are disappearing.

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Vegetables

What is blanching?
Heating or scalding the vegetables in boiling water or steam for a short period of time.

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Is it recommended to blanch vegetables before freezing?
Yes. Blanching slows or stops the action of enzymes which cause loss of flavor, color and texture. Blanching cleanses the surface of dirt and organisms, brightens the color and helps retard loss of vitamins. Blanching also wilts or softens vegetables and makes them easier to pack.

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How do you blanch vegetables?
Use a wire blanching basket and covered saucepan, or fit a wire basket into a large kettle with fitted lid. Use one gallon of water per pound of prepared vegetable. Put vegetable in blanching basket and lower it into vigorously boiling water. Place lid on blancher and start counting blanching time as soon as the water returns to a boil. (The water should return to boiling within 1 minute, or you are using too much vegetable for the amount of water). Keep heat high for total blanching time.

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Why is it necessary to cool vegetables after blanching?
Vegetables should be cooled quickly and thoroughly after blanching to stop the cooking process. Otherwise, vegetables will be overcooked with loss of flavor, color, vitamins and minerals.

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What causes frost or ice crystals to appear on the surface of frozen vegetables such as broccoli?
Inadequate draining of vegetables before freezing, slow freezing or fluctuation of storage temperatures above 0°F may cause undesirable formation of large and excessive ice crystals. This can affect the texture as well as appearance of frozen vegetables.

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Can I blanch in my microwave oven?
Microwave blanching may not be as effective as other methods, since research has shown that some enzymes may not be inactivated. This could result in off flavors and loss of texture and color. Those wishing to run the risk of low quality vegetables by microwave blanching should be sure to work in small quantities, using the directions for their specific microwave oven. Microwave blanching will not save time or energy.

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Can vegetables be fully cooked before freezing?
Some fully cooked vegetables, such as baked beans and candied sweet potatoes, maintain high quality for many months when frozen. Most fully cooked vegetables, however, have less desirable color, aroma and flavor when reheated. Loss of flavor may be retarded by covering the vegetable with cooking liquid, meat broth or cream sauce.

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Does it matter how long vegetables are blanched?
Blanching time is crucial and varies with the vegetables and size. Under-blanching stimulates the activity of enzymes and is worse than no blanching. Overblanching causes loss of color, flavor, vitamins and minerals.

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Are frozen vegetables safe to eat if they are not blanched?
Yes. They are safe to eat, but the quality (color, flavor and texture) will be poorer than that of vegetables which have been blanched. Blanching slows or stops the action of enzymes which cause loss of flavor, color and texture.

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How can you prevent corn-on-the-cob from tasting "cobby"?
After blanching ears for the recommended time, chill immediately with ice water until the cobs are completely cold. Partially thaw the ears of corn before cooking.

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Should frozen vegetables be thawed before cooking?
For most vegetables, no. You get a fresher tasting product if it has not been thawed. Exceptions are corn-on-the cob and leafy greens which cook more evenly if partially thawed first.

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Is it necessary to wash peas and lima beans before shelling?
Any vegetable should be washed before shelling to remove any foreign material such as dirt, insects, leaves, etc.

Animal Products

Is it necessary to thaw meat or fish before cooking?
No, meat and fish can be cooked from the frozen state if extra cooking time is allowed. The amount of time will depend on the size and shape of the cut. Large frozen roasts can take as much as 11/2 times as long to cook as unfrozen cuts of the same weight and shape. Small roasts and thin cuts such as steaks and chops require less time.

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Can meat and poultry be thawed in the conventional oven?
No, meat and poultry should never be thawed in the conventional oven or at room temperature. There is greater danger of bacterial growth and food spoilage for food thawed at room temperature. Thaw meat and poultry in the refrigerator in the original wrappings. To speed thawing, loosen the wrapping. To keep other foods safe, put the thawing meat and poultry in a pan on the bottom shelf. For a quicker method, immerse meat or poultry in a watertight bag into cold water. Thaw until it is pliable. Meat and poultry can also be thawed quickly and safely in the microwave oven, followed by immediate cooking, either in the microwave oven or by some other method. Because microwave ovens vary, check your manufacturer's instructions for information on how to safely thaw in your microwave oven. Frozen meat and poultry can also be cooked without thawing.

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Why is it important to chill meat or poultry before freezing?
Slaughtered meat and poultry should be put under refrigeration (32 - 36°F) immediately to remove animal heat from the carcass. Prompt and thorough chilling is important to reduce bacterial growth and decrease the action of enzymes which can lower the quality. Bone souring in beef and pork may also occur if carcasses are not properly chilled. Chill pork, lamb or veal 24 hours; beef 5 to 7 days.

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Can stuffed turkey be frozen?

Stuffing should be frozen separately from the turkey. With any food, the time needed for freezing to take place in the center of the item is the critical factor.

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