Freezing vegetables is simple and easy. Freezing costs more than canning or drying, but preserves more nutrients and a fresher flavor if done properly.
Freezing does not completely destroy bacteria, molds, and yeasts but does retard their growth. Once food is thawed, microorganisms may continue to grow.
Natural enzymes in vegetables cause flavor, color, texture, and nutritive value changes. Freezing slows enzyme activity but does not stop it. Frozen vegetables will become tough and lose flavor during storage unless enzyme activity is stopped by blanching before freezing.
Vegetables loose quality rapidly after harvesting. Harvest only an amount you can prepare to freeze within 2 or 3 hours. If this is not possible, refrigerate vegetables, then freeze as soon as possible.
Choose young, tender vegetables to freeze. Over-mature vegetables may be hard, tough, or flavorless.
To remove dirt, bacteria, and pesticide residue, wash vegetables thoroughly in cold water. Drain and rinse several times with cold water. Lift vegetables from water to prevent redepositing of dirt and residues. Peel, trim, and cut into pieces as directed for each vegetable on the chart included on pages 2 to 3 of this fact sheet.
Air leads to flavor loss or off-flavors. If moisture evaporates, frozen food becomes dry, tough, and may develop grayish spots called "freezer burn." To prevent air exposure and moisture loss, use only moisture-proof, vapor-proof packaging designed for freezing. Examples are "can or freeze" glass jars, plastic freezing containers, heavyweight aluminum foil, plastic-coated freezer paper, and polyethylene wrap and bags. Only sealing tape designated for freezer use will adhere at freezing temperatures. Freezer bags can be placed in rigid containers for easy stacking.
Pack vegetables tightly in freezer bags or rigid containers. Squeeze air from bags before sealing. Leave 1/2-inch headspace for expansion in rigid containers.
For loose pack, freeze vegetables pieces in a single layer on a tray until nearly solid. Package at once. Label and date product and return it to freezer immediately.
Because water in vegetables expands during freezing and breaks cell walls, thawed foods may "leak" and have a soft texture. To retain quality, freeze vegetables quickly at lowest possible freezer setting. Freeze only 2 to 3 pounds of food per cubic foot of available freezer storage space in 24 hours.
Maintain freezer at 0 degrees Fahrenheit (F) or less. If power fails, keep freezer closed; food should stay frozen 24 to 48 hours. If available, protect food with 25 pounds of dry ice per 10 cubic feet of freezer space. Food can be safely refrozen if it still contains ice crystals. Some loss of quality and food value will occur.
The more food put into a freezer in a year, the less the operating cost per pound. Keep an inventory and use the oldest foods first. Use frozen vegetables within one year.
Most frozen vegetables can be cooked without thawing; corn on the cob should be partially thawed. Cook vegetables in 1/2 cup or less water per pint package. Drain and season as desired.
Use 1 gallon of water per 1 pound of vegetables (2 gallons for leafy greens). Place vegetables in wire basket or mesh bag; immerse in boiling water. Cover. Start counting blanching time immediately.
Place one layer of vegetables in a wire basket. Suspend in steamer above several inches of rapidly boiling water and cover. Steam 1 1/2 times longer than boiling water blanch time.
Conventional blanching is more reliable than microwave blanching, which is uneven and unpredictable. If used, follow directions given by microwave manufacturer. Expect variable results. Microwave blanching is suitable for small quantities only.
Some vegetables do not make satisfactory products when frozen, including green onions, lettuce and other salad greens, radishes, and tomatoes (except as juice or cooked). These vegetables can be stored for short periods in the refrigerator. Contact you local Ohio State University Extension office for information on proper storage.
For popular varieties of vegetables to grow in Ohio, see Ohio State University Extension bulletin 736, Vegetables for Ohio Gardens.
| Table 1. Preparation and boiling water blanch times for common vegetables | |
|---|---|
| Vegetable | Preparation and boiling water blanch times |
| Asparagus | Leave whole or cut into 2-inch lengths. Blanch small stalks 2 minutes; medium stalks 3 minutes; large stalks 4 minutes. Cool promptly and drain. |
| Beans (green and yellow podded) | Snip tips and sort by size. Cut or break into suitable pieces or freeze small beans whole. Blanch 3 minutes. Cool promptly and drain. |
| Beans, fresh lima | Shell and sort. Blanch small beans 2 minutes; medium beans 3 minutes; large beans 4 minutes. Cool promptly and drain. |
| Beets | Remove all but 2 inches of top; wash. Cook tender for 25 to 30 minutes for small beets; 45 to 50 minutes for medium beets. Chill. Remove skins. Slice or dice large beets. Pack. |
| Broccoli and cauliflower | Trim. Separate into individual pieces. Cut broccoli stalks lengthwise. Soak 1/2 hour in salt brine (4 teaspoons of salt to 1 gallon cold water) to drive out small insects. Rinse and drain. Blanch 3 minutes in water or steam blanch 5 minutes. Cool promptly and drain. |
| Brussels sprouts | Trim. Soak 1/2 hour in salt brine (see above). Rinse and drain. Blanch small heads 3 minutes; medium heads 4 minutes; large heads 5 minutes. Cool promptly and drain. |
| Cabbage | Discard coarse outer leaves. Cut into wedges or shred coarsely. Blanch wedges 3 minutes and shredded cabbage 1 1/2 minutes. Cool promptly and drain. |
| Carrots | Trim and scrape. Dice or slice 1/4-inch thick. Blanch cut carrots 3 minutes; whole carrots 5 minutes. Cool promptly and drain. |
| Sweet corn, on-the-cob | Husk, remove silks, and trim ends. Use a large kettle for blanching. Blanch small ears (1 1/4-inch diameter) 7 minutes; medium ears (1 1/4- to 1 1/2-inch diameter) 9 minutes; large ears (over 1 1/2-inch diameter) 11 minutes. Chill in ice water for as long as it takes to blanch or corn may become mushy and develop a cob flavor. |
| Sweet corn, cut | Husk, remove silks, and trim ends. Blanch 4-6 minutes, depending on size of ear. Chill. Cut from cob. |
| Kohlrabi | Cut off tops and roots. Wash and peel tough bark. Wash and slice 1/4-inch thick, dice in 1/2-inch cubes, or leave whole. Blanch cubes 1 minutes; slices 2 minute; whole 3 minutes. Cool promptly and drain. |
| Vegetable | Preparation and boiling water blanch times |
| Mushrooms | Trim stem ends. Sort by size. Freeze small ones whole; slice larger ones. To prevent discoloration, use 3 teaspoons lemon juice or 1/2 teaspoon ascorbic acid to 1 quart water when blanching. Blanch whole 4 minutes; sliced, 3 minutes. Cool and drain. |
| To steam blanch: Dip for 5 minutes in a solution of 1 teaspoon lemon juice or 1 1/2 teaspoon citric acid to 1 pint water. Steam whole 5 minutes; buttons or quarters 3 1/2 minutes; sliced 3 minutes. | |
| Sauteed: Heat small quantities of mushrooms in butter for 3 minutes. Cool and pack. No blanching is required. | |
| Okra | Cut off stems without opening seed cells. Blanch small pods 3 minutes; large pods 4 minutes. Leave whole or slice crosswise. Cool promptly and drain. |
| Peas (green, English, black-eyed) | Shell small amount at a time. Blanch green or English for 1 1/2 minutes; black-eyed 2 minutes. Cool promptly and drain. |
| Peas (edible pod, sugar, or Chinese) | Remove stems, blossom ends, and any string. Leave whole. Blanch small pods 1 1/2 minutes; large pods 2 minutes. Cool promptly and drain. |
| Peppers, green | Remove stem and seeds. Halve, chop, or cut into 1/2-inch strips or rings. May be frozen without blanching. For use in cooking, blanch halves 3 minutes, strips or rings 2 minutes. Cool, drain, and package. |
| Peppers, hot | Wash and stem. Package leaving no headspace. |
| Pimentos | Peel by roasting in oven at 400-450 degrees F for 6-8 minutes or until skins can be rubbed off. Wash off charred skins, cut out stems, remove seeds. Package. |
| Potatoes, Irish | Plain: Wash and peel or scrub. Blanch 3-5 minutes depending on size. Cool, drain. |
| French fried: Use potatoes that have been stored at least 30 days. Wash, peel, and cut into thin strips. Rinse in cold water, dry thoroughly. Fry in hot fat (360 degrees F) about 5 minutes until tender, not brown. Drain on paper towels. Cool and package. Finish browning at serving time in a hot oven (475 degrees F). | |
| Potatoes, sweet | Choose potatoes that have been cured for at least one week. Sort to size and wash. Cook until almost tender (in water, pressure cooker, oven). Cool at room temperature, peel and cut in halves, slice or mash. |
| To prevent darkening: Dip whole potato or slices in a solution of 1/2 cup lemon juice to 1 quart water for 5 seconds. | |
| For mashed sweet potatoes: Mix 2 Tablespoons orange or lemon juice with each quart. | |
| Spinach and other greens | Remove damaged leaves and tough stems. Blanch collards 3 minutes; other greens 2 minutes. Cool promptly and drain. |
| Summer squash, zucchini | Peel; cut in 1/2-inch slices; blanch 3 minutes. Steam shredded zucchini 1-2 minutes or until translucent. Cool promptly and drain. |
| Tomatoes | Raw: Wash and dip in boiling water for 30 seconds to loosen skins. Core and peel. Freeze whole or in pieces. Use for cooking or seasoning only. |
| Juice: Wash, sort, and trim. Cut in quarters or eighths. Simmer 5-10 minutes. Press through sieve. If desired, add 1 teaspoon salt per quart. Pour into containers, leaving headspace. | |
| Stewed: Prepare as in juice. Cover and cook until tender, 10-20 minutes. Cool and pack leaving headspace. |
Ball Blue Book (Vol. 1) (1995). Ball/Alltrista Corporation, Muncie, Indiana.
How to Freeze the Right Way: Gerald D. Kuhn and Anne V.A. Resurricion, Cooperative Extension Service, The Pennsylvania State University.
Preserving Food Safely (Version 3.0). Home Economics Library Program, Cooperative Extension Service, Michigan State University.
Putting Food By (Fourth Ed.). Janet Green, Ruth Hertzberg, Beatrice Vaughn, The Stephen Greene Press, Lexington, Massachusetts.
So Easy to Preserve (Third Ed.) (1993). Cooperative Extension Service, The University of Georgia.
Sharon L. Mader, Extension Agent, Family and Consumer Sciences/4-H, Sandusky County
Pat Shenberger, Extension Agent, Family and Consumer Sciences, Ashland County
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