Freezing is one of the simplest and least time-consuming methods of food preservation. Under optimal conditions, freezing is the best form of food preservation in terms of retaining nutrients, flavor, and texture.
Freezing does not kill most microorganisms (except trichinae and fish parasites); it just puts them to sleep. Therefore, it is important to handle foods safely prior to freezing and when defrosting. Always wash your hands, surfaces, cutting boards, and knives before preparing foods for freezing.
For best quality, follow directions carefully. Color, flavor, and nutritive value can be affected by the freshness of the produce selected, method of preparation and packaging, and conditions of freezing.
(See Freezing fruits, tables 1 and 2 for specific directions.)
Any fruit can be frozen without sugar. However, the texture may be softer than that of fruit frozen with sugar.
Fruits such as berries, cherries, and grapes may be frozen in a single layer on cookie sheets before packing in containers. This prevents them from sticking together. Serve them frozen as snacks or thaw and use as a topping for salads or desserts.
If desired, a water pack (without sugar) can be used for fruit such as peaches. Fruit juice (either extracted from the fruit or purchased) can also be used. Orange, grape, apple, and berry juices are suitable.
Fruits that will be served uncooked are often packed in a sugar syrup. The syrup may be prepared from either cane or beet sugar. If desired, part of the sugar may be replaced by honey. Select the strength of syrup that will give the desired flavor. (This will depend on the sweetness of the fruit, personal preference, and intended use.) Allow about ⅔ cup of syrup for each pint of fruit and 1⅓ cups for each quart of fruit. Dissolve sugar in hot or cold water. If hot, cool before using. See Syrup Strength Table for preparing light, medium, and heavy syrups.
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Strength of syrup |
Water |
Sugar |
Yield |
|
Light |
4 cups |
1 cup |
4¾ cups |
|
Medium |
4 cups |
1¾ cups |
5 cups |
|
Heavy |
4 cups |
2¾ cups |
5½ cups |
Headspace to allow between packed food and closure |
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Type of pack |
Container with wide top opening |
Container with narrow top opening |
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Pint |
Quart |
Pint |
Quart |
|
Liquid pack* |
½ inch |
1 inch |
¾ inch |
1½ inch |
Dry pack** |
½ inch |
½ inch |
½ inch |
½ inch |
Juices |
1½ inch |
1½ inch |
1½ inch |
1½ inch |
Freeze fruits and vegetables as soon as possible after they are packed. If there will be a delay before freezing, keep packages in the refrigerator.
Foods that freeze too slowly may lose quality or spoil. Only put the amount of unfrozen food into a home freezer that will freeze within 24 hours. Usually this will be about 2 or 3 pounds of food for each cubic foot of freezer capacity. For fastest freezing, place packages in a single layer against freezing plates or coils. Leave a little space between them so that air can circulate freely. Make sure the packages are completely dry so they don’t freeze to the freezer. Stack after frozen. See Headspace Table to determine how much headspace to allow for different size containers.
After freezing, packages may be stored close together. Store them at 0°F (-18°C) or below. Foods lose quality and nutritive value much faster at higher temperatures. Use a freezer thermometer to monitor the temperature.
Most fruits and vegetables maintain high quality for 8 to 12 months. (Unsweetened fruits lose quality faster than those packed in sugar or syrup.) Storage for longer periods will affect the quality of the frozen foods, but they will be safe to eat.
Keeping a freezer inventory and dating packages will help to rotate the supply.
Occasionally a home freezer stops running. The length of time food will stay frozen depends on the amount of food in the freezer and the temperature of the food. A full load of food will stay frozen for up to 2 days if the freezer is not opened. Dry ice can be used to keep foods frozen longer. If the power will be off for a long period of time, food should be transferred to a working freezer.
It is safe to refreeze fruits and vegetables that still contain ice crystals. For best quality, refreeze food in small quantities.
If the temperature has warmed above 40°F (5°C), foods may not be safe for refreezing. Check your freezer thermometer to determine the temperature.
Do not eat thawed vegetables that are above 40°F. The low acidity of vegetables makes it possible for harmful bacteria to grow. Unsafe products may not show obvious signs of spoilage.
For information about the safety of specific foods, call your local Extension office. Be prepared to give the “history” of the food (length of time that the power was off and temperature of the food before the freezer began to run again).
Freezing fruits
Fruits may also be frozen as purées and for making jams. For light-colored fruits, use ascorbic acid to prevent browning. Store at 0°F (-18°C) or below for top quality. You can also freeze some fruits such as berries, cherries, and grapes in a single layer on cookie sheets before packing in containers. This prevents them from sticking together.
Fruit |
Preparation |
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Apples |
Select crisp, firm fruit (not mealy). Wash, peel, core, and slice. To prevent browning during preparation, slice into ascorbic acid solution (3,000 mg ascorbic acid to 1 gallon of water). Drain. Pack in cold syrup, sugar (or artificial sweetener), or without sugar. Syrup pack is preferred for apples that will be used for uncooked desserts or fruit cocktail. A sugar pack is good for making pie. |
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Applesauce |
Wash apples, peel (if desired), core, and slice. Cook until tender, adding a small amount of water to prevent burning or sticking. Strain through a food mill if desired and mash to desired texture. Sweeten to taste. Cool and pack. |
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Apricots |
Select firm, ripe, uniformly yellow fruit. Wash, halve, and pit. Peel and slice, if desired. To loosen skins, score skin and dip in boiling water until skin starts to split. If apricots are not peeled, heat them in boiling water for 30 seconds to keep skins from toughening during freezing. Cool in ice water and drain. Pack in syrup or sugar (or artificial sweetener). Use ascorbic acid to retard browning. |
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Avocados |
Best frozen as purée (not whole or sliced). Select avocados that are soft and with rinds free from dark blemishes. Wash, peel, halve, and remove pit. Mash the pulp. For better quality, add ¼ teaspoon of ascorbic acid per quart. Pack without sugar if using for salads, dips, or sandwiches. |
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Bananas |
Select firm, ripe bananas. Wash, peel, and mash thoroughly. To retard browning, add ½ teaspoon (1,500 mg) ascorbic acid per cup of mashed bananas. Bananas can also be frozen in their skin (packed in a freezer container). |
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Blackberries |
Also boysenberries, marionberries and loganberries. Select firm, fully ripe fruit with glossy skins. Wash carefully and drain. Discard any soft, underripe, or defective fruit. Pack in syrup, sugar (or artificial sweetener), or without sugar. Blackberries can also be frozen in a single layer on a cookie sheet before packing. |
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Blueberries |
Also huckleberries. Select ripe berries with tender skins. For dry pack without sugar, wash, drain, dry, and pack berries into freezer bags or containers. Blueberries can also be frozen in a single layer on a cookie sheet before packing. Blueberries can also be crushed or puréed, then frozen. Wash berries. Crush by pressing berries through a fine sieve, or purée in a blender or food processor. Mix 1⅛ cups of sugar with each quart of crushed or puréed berries, if desired. Stir until sugar is dissolved. Pack in freezer container. |
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Cantaloupe |
Also other melons. Select firm, well-colored, ripe melons. Wash skin with vegetable scrub brush. Cut in half, remove seeds, and peel. Cut into slices, cubes, or balls. Pack in syrup. |
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Cherries, sour |
Select bright red, tree-ripened fruit. Stem and wash. Drain and pit. Pack in syrup, sugar (or artificial sweetener), or without sugar. Use ascorbic acid to retard browning, if desired. |
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Cherries, sweet |
Select tree-ripened, deep-colored varieties. Stem and wash. Drain and remove pits if desired. Pack in syrup or pack without sugar. |
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Cranberries |
Choose firm, deep red berries with glossy skins. Stem and sort. Wash and drain. Pack in syrup or without sugar. Cranberries can also be frozen in a single layer on a cookie sheet before packing. |
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Currants |
Select fully ripe, bright red fruit. Wash and stem. Pack in syrup, sugar (or artificial sweetener), or without sugar. |
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Dates |
Select dates with good flavor and tender texture. Wash and split to remove pits. Leave whole or press through a sieve for purée. Pack without sugar. |
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Figs |
Select tree-ripened, soft, ripe fruit. Wash and cut off stems. Peel, if desired. Slice or leave whole. Pack in syrup or without sugar. Use ascorbic acid to retard browning. |
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Gooseberries |
Select fully ripe (for pie) or slightly underripe (for jelly) berries. Wash and remove stems and blossom ends. Pack without sugar (for use in pies or preserves). |
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Grapes |
Choose fully ripe, firm, sweet grapes. Sort, stem, and wash. Leave seedless grapes whole; cut table grapes with seeds in half and remove seeds. Pack in syrup or pack without sugar. Grapes can also be frozen in a single layer on a cookie sheet before packing. Grapes can also be puréed. Wash, stem, and crush the grapes. Heat to boiling. Drain off free juice and freeze it separately. Remove seeds and hulls with a colander. To one quart purée, add ½ cup sugar. Pack in freezer containers. |
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Grapefruit |
Also oranges. Select firm, tree-ripened fruit, heavy for its size and free from soft spots. Wash fruit. Remove all peel, membranes, and seeds. Divide fruit into sections, or slice, if desired. Pack in syrup (made with excess juice and water if needed) or pack in water without sugar. |
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Nectarines and peaches |
Select firm, fully ripe, well-colored fruit. Handle carefully to avoid bruising. Wash, peel, and remove pit. Cut in halves, quarters, or slices. Pack in syrup, orange juice, water without sugar, or pack dry with sugar (or artificial sweetener). Use ascorbic acid to retard browning. Nectarines and peaches can also be frozen crushed or puréed. Coarsely crush peeled and pitted nectarines or peaches. For purée, press through a sieve or purée in blender or food processor (heating pitted nectarines or peaches for 4 minutes in just enough water to prevent scorching makes them easier to purée). For better quality, add ⅛ teaspoon ascorbic acid to each quart of fruit. Pack into freezer containers. |
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Pears |
Select well-ripened, firm fruit. Wash and peel. Cut in halves or quarters and remove cores. Heat in boiling syrup for 1 to 2 minutes (depending on size of pieces). Drain, cool, and pack in syrup. Use ascorbic acid to retard browning. |
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Persimmons |
Select orange, soft, ripe persimmons. Sort, wash, peel, and cut into sections. Press fruit through a sieve or blend in a blender to make a purée. To each quart of purée, add ⅛ teaspoon ascorbic acid. Purées may be made with or without sugar. Pack in freezer containers. |
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Plums |
Also prunes. Select firm, tree-ripened fruit. Wash. Leave whole, or cut in halves or quarters; remove pits. Pack in syrup or without sugar. Use ascorbic acid to retard browning. |
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Raspberries |
Select fully ripe, juicy berries. (Seedy berries are best for purées or juice.) Wash and drain. Pack in syrup, sugar (or artificial sweetener), or without sugar. |
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Rhubarb |
ESelect firm, well-colored stalks with good flavor and few fibers. Wash, trim, and cut into ½-inch pieces. Blanching rhubarb in boiling water for 1 minute and cooling promptly in ice water will help retain color and flavor. It can also be frozen raw. Pack in syrup or without sugar. |
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Strawberries |
Select firm, ripe, red berries. Wash, drain, and remove hulls. Slice, if desired. Pack the fruit alone or with syrup, sugar, or artificial sweetener. |
Vegetable |
Preparation |
Blanching times (minutes): In boiling water |
Blanching times (minutes) In steam |
Asparagus |
Select young stalks with compact tips. Wash and sort by size. Leave whole or cut in 1- to 2-inch lengths. Blanch, cool, drain, and pack, leaving no headspace. |
Small stalk: 2 Medium stalk: 3 Large stalk: 4 |
3 5 6 |
Beans—green (snap or wax) |
Select young, stringless beans. Wash, snip off tips. Cut or break into suitable pieces or slice lengthwise into strips. Blanch, cool, drain, and pack leaving ½-inch headspace. |
3 |
5 |
Beans—pinto, lima, or butter |
Harvest beans while seeds are green. Wash, shell, and sort according to size. Blanch, cool, drain, and package leaving ½-inch headspace. |
Small: 2 Medium: 3 Large: 4 |
3 5 6 |
Beets |
Select deep, uniformly red, tender, young beets. Wash and sort by size. Trim tops, leaving ½-inch of stems and tap root to prevent bleeding of color during cooking. Cook in boiling water until tender (small beets 25 to 30 minutes; medium beets 45 to 50 minutes). Cool promptly in cold water. Peel, remove stem and tap root, and cut into slices or cubes. Package leaving ½-inch headspace. |
Cook |
— |
Broccoli |
Select firm, young, tender stalks with compact heads. Wash and trim leaves and woody ends. If necessary to remove insects, soak 30 minutes in salt brine (4 teaspoons salt to 1 gallon of water). Rinse and drain. Cut through stalks lengthwise, leaving heads 1 inch in diameter. Blanch, cool, drain, and pack head and stalk ends alternately in container. Leave no headspace. |
3 |
5 |
Brussel sprouts |
Select green, firm, compact heads. Wash and trim outer leaves. Soak 30 minutes in salt brine (see broccoli). Rinse and drain. Blanch, cool, drain, and package leaving no headspace. |
Small heads: 3 Medium heads: 4 Large heads: 5 |
5 6 7 |
Carrots |
Select tender carrots. Remove tops, wash, and peel. Dice or slice lengthwise ¼-inch thick. Blanch, cool, drain, and package leaving ½-inch headspace. |
Small: 5 Diced or sliced: 2 |
8 3 |
Cauliflower |
Select firm, white heads. Wash and trim. Split heads into pieces 1 inch across. If necessary to remove insects, soak 30 minutes in salt brine (4 teaspoons salt to 1 gallon of water). Rinse and drain. Blanch, cool, drain, and package leaving ½-inch headspace. |
3 |
5 |
Celery |
Celery loses its crispness when frozen, so it is suitable only for cooked dishes. Select crisp, tender stalks, free from coarse strings. Wash thoroughly, trim and cut stalks into 1-inch lengths or desired size for cooking. Blanch, cool, drain, and package leaving no headspace. |
3 |
— |
Corn—on cob |
Select ears with plump kernels and thin, sweet milk. Husk, remove silk, and wash. Blanch, cool promptly, and drain. Wrap each ear separately or tightly pack desired number in large freezer bags or containers. |
Small: 7 Medium: 9 Large: 11 |
10 13 16 |
Corn—cream style |
Select tender, freshly gathered corn in the milk stage. Husk and trim the ears, remove silks, and wash. Blanch, cool promptly, and drain. Cut kernel tips and scrape the cobs with the back of a knife to remove the juice and the heart of the kernel. Package leaving ½-inch headspace. Another way to prepare cream-style corn for freezing is to cut and scrape the corn from the cob without blanching. Place the cut corn in a double boiler and heat with constant stirring for about 10 minutes or until it thickens; allow to cool by placing the pan in ice water. Package in moistureand vapor-resistant containers, leaving ½-inch headspace. |
4 |
6 |
Corn—whole kernel |
Select tender, freshly gathered corn in the milk stage. Husk and trim the ears, remove silks, and wash. Blanch, cool promptly, drain, and cut from cob. Cut kernels from cob about ⅔ the depth of the kernels. Package leaving ½-inch headspace. |
4 |
6 |
Eggplant |
Harvest before seeds become mature and when color is uniformly dark. Wash, peel, and slice ⅓-inch thick. Prepare quickly, enough eggplant for one blanch at a time. Blanch in 1 gallon of boiling water containing ½ cup lemon juice. Cool, drain, and package leaving ½-inch headspace. |
4 |
6 |
Herbs—fresh |
Wash, drain, and pat dry with paper towels. Wrap a few sprigs or leaves in freezer wrap and place in a freezer bag. Chop and use frozen herbs in cooked dishes. |
— |
— |
Kohlrabi |
Select stems when fully grown but tender. Cut off tops and roots. Wash and peel off the tough bark. Leave whole or dice in ½-inch cubes. Blanch, cool, drain, and package leaving ½-inch headspace. |
Whole: 3 Cubes: 1 |
— — |
Mushrooms |
Select edible mushrooms free of spots or decay. Wash and remove stem base. Freeze small mushrooms whole; cut large ones into four or more pieces. Mushrooms can be steamed or heated in fat in a fry pan. Steamed mushrooms will keep longer than those heated in fat. To steam: Mushrooms to be steamed will have better color if first given anti-darkening treatmen. To do this, dip for 5 minutes in a solution containing 1 teaspoon lemon juice or 1½ teaspoons citric acid to a pint of water. Then steam, cool promptly, drain, and package leaving ½-inch headspace. To heat in fry pan: Heat small quantities of mushrooms in margarine or butter in an open fry pan until almost done. Cool in air or set pan in which mushrooms were cooked in cold water. Package leaving ½-inch headspace. |
— |
Whole: 9 Buttons: 9 Slices: 5 |
Onions |
Select fully mature onions. Peel and wash. Blanch, cool, drain, and package leaving ½-inch headspace. Onions (including green onions) may also be frozen diced and unblanched. |
3-7 |
— |
Peas—edible pod |
Select young, bright green, flat, tender pods. Wash. Remove stems, blossom ends, and any strings. Blanch, cool, drain, and package leaving ½-inch headspace. NOTE: If the peas have started to develop, follow the directions for green beans. If the peas are already developed, shell and follow the directions for green peas. |
Small pods: 2 Large pods: 3 |
4 5 |
Peas—green |
Harvest when pods are filled with young, tender peas that have not become starchy. Wash and shell. Blanch, cool, drain, and package leaving ½-inch headspace. |
1½–2½ |
3-5 |
Peppers—sweet (green) |
Select crisp, tender, green or bright red peppers. Wash, cut out stems, cut in half, and remove seeds. Slice or dice. Blanch, cool, drain, and package leaving ½-inch headspace. May also be frozen unblanched. |
Halves: 3 Strips: 2 |
5 3 |
Peppers—hot (green chile) |
Select firm, smooth peppers. Wash and dry. Protect hands with rubber gloves. Broil for 6 to 8 minutes to loosen skin. (First make a small slit in each to allow steam to escape.) Cool. Remove peel, seeds, and stems before or after freezing. Chop if desired. Package leaving no headspace. Hot peppers can also be frozen without heating first. Wash and stem peppers. Chop if desired. Package leaving no headspace. |
— |
— |
New Irish potatoes |
Select smooth new potatoes directly from the garden. Wash and peel or scrape. Blanch, cool, drain, and package leaving ½-inch headspace. For French fries: Wash, peel, and cut into ⅓-inch sticks lengthwise, then crosswise into ⅓-inch strips. Rinse in cold water. Dry thoroughly. Fry small amounts in deep, hot fat (360°F) about 5 minutes until tender but not brown. Drain on paper towel. Cool. Package leaving no headspace. To serve, finish browning potatoes in a hot oven (475°F). |
3-5 |
5-8 |
Potatoes— sweet |
Select medium to large sweet potatoes. Wash and cook until almost tender. Cool. Peel, cut in halves, slice, or mash. To prevent browning, dip sweet potatoes 5 seconds in a solution of ½ cup lemon juice to 1 quart of water. To keep mashed sweet potatoes from darkening, mix 2 tablespoons orange or lemon juice with each quart of mashed sweet potatoes. Package leaving ½-inch headspace. Baked: Wash, trim, and bake potatoes (with skin on) in oven until slightly soft. Cool completely, remove peel, and wrap individually in aluminum foil. Place in freezer bag and freeze. Complete the baking in an oven at 350°F immediately before serving, leaving potatoes wrapped in foil. |
Cook |
— |
Pumpkin |
Also other winter squash. Select full-color, mature pumpkin. Wash with vegetable scrub brush. Cut into fairly uniform pieces. Remove seeds. Cook until soft in oven or pressure cooker, or by steaming. Cool promptly, scoop pulp from rind, and mash or put through ricer. Package leaving ½-inch headspace. |
Cook |
— |
Spinach |
Also other greens. Select young, tender leaves. Remove tough stems. Wash. Blanch, cool, drain, and package leaving ½-inch headspace. |
Collards: 3 Spinach/others: 2 |
5 3 |
Tomatoes |
Select firm, ripe tomatoes. Raw: Wash and dip in boiling water for 30 seconds to loosen skins. Core and peel. Freeze whole or in pieces. Package leaving 1-inch headspace. Seal and freeze. Use only for cooking or seasoning as tomatoes will not be solid when thawed. Raw tomatoes can also be frozen with skin on. Stewed tomatoes: Remove stem ends, peel, and quarter ripe tomatoes. Cover and cook until tender (10 to 20 minutes). Place pan containing tomatoes in cold water to cool. Package leaving headspace (see table on page 6 for amount). Juice: Cut in quarters or eighths. Simmer 5 to 10 minutes. Press through a sieve. If desired, season with 1 teaspoon salt to each quart of juice. Pour into freezer containers leaving headspace (see table on page 6 for amount). |
Cook |
— |
Turnips or parsnips |
Select small to medium, firm turnips or parsnips that are tender and have a mild flavor. Wash, peel, and cut into ½-inch cubes. Blanch, cool promptly, drain, and package leaving ½-inch headspace. |
3 |
5 |
Zucchini |
Also other summer squash. Choose young squash with tender skin. Wash and cut in ½-inch slices. Blanch, cool promptly, drain, and package leaving ½-inch headspace. Grated zucchini (for baking): Choose young, tender zucchini. Wash and grate. Steam blanch in small quantities. Pack in measured amounts, leaving ½-inch headspace. Cool by placing the containers in cold water. Freeze. If watery when thawed, discard the liquid before using the zucchini. |
Slices: 3 Grated: — |
5 1-2 |