Vegetable Freezing Methods
Choose fresh, tender vegetables. The fresher the vegetables, the more satisfactory the final product.
Wash thoroughly in cold water. Peel trim and cut into pieces according to the directions for each vegetable below.
Heating or blanching is an important step in preparing vegetables for freezing. The heat is needed to inactivate enzymes. This prevents loss of flavor and color during storage. The heating also wilts or softens vegetables and makes them easier to pack. Vegetables may be heated in the following ways:
In boiling water
This is the recommended heating method for most vegetables. Put vegetables in a basket then place in kettle of boiling water, cover with a lid and begin timing immediately.
Put a single layer of vegetables in rack or basket above 1–2 inches of boiling water in a kettle. Place tight fitting lid on kettle and begin timing.
Recent information has been published for use of the microwave to blanch small amounts of vegetables prior to freezing. You can expect good results if you follow the recommendations; however, uneven heating is the primary concern in using a microwave for blanching.
in blanching. Allow 1 minute longer at 5,000 or more feet above sea level. Following the heat treatment, cool or chill the product rapidly and completely by immersing the vegetables in ice water to chill. Drain thoroughly before packaging.
Pack cold foods into waterproof containers or bags. Pack tightly, press air out before sealing. Allow ½ inch headspace in rigid containers for expansion.
Use tender tips. Wash, discard tough parts of stalk. Leave whole or cut in preferred lengths. Small stalks—2 minutes; medium stalks—3 minutes; large stalks—4 minutes.
Snap. Use young, tender, stringless. Wash, remove green or wax ends and stems. Cut crosswise or French Julienne style. Blanch 3 minutes.
Use young, tender, not more than 3 inches across. Wash and sort as to size. Trim tops leaving ½ inch. Cook until tender, 25–30 minutes. Cool. Skin, slice or dice.
Use compact, dark green heads. If necessary to remove insects, soak ½ hour in a solution of 4 teaspoons salt to 1 gallon water. Split lengthwise so that flowerettes are not more than 1½ inches across. Blanch approximately 3 minutes depending on thickness, or steam for 5 minutes.
Use green, firm heads. Cut from stems. Remove coarse outer leaves. Wash thoroughly. Blanch small heads—3 minutes; medium heads—4 minutes; large heads—5 minutes.
Use small, young carrots. Wash, remove tops, scrape or peel, if desired. Small carrots may be left whole, diced or sliced. Blanch whole carrots, small—5 minutes; diced or sliced—2 minutes; lengthwise strips—2 minutes.
Use compact, tender, white heads. Break into 1-inch pieces. Wash well. If necessary to remove insects, soak ½ hour in a solution of 4 teaspoons salt to 1 gallon of water. Blanch 3 minutes in boiling water containing 4 teaspoons salt per gallon of water.
Sweet. Use young, tender ears, thin sweet milk. On cob. Husk, remove silk. Wash and trim. Blanch small ears 7 minutes; medium ears—9 minutes; large thick ears—11 minutes.
Sweet. Use young, tender ears, thin sweet milk. Whole kernel. Husk, remove silk. Wash and trim. Heat ears 4 minutes. Cool, drain. Cut kernels from cob.
Use small to medium mushrooms, free from spots, white, tight caps. Wash, remove base of stem. If larger than 1 inch across, slice or cut into quarters. To prevent darkening, soak for 5 minutes in a solution of 1 teaspoon lemon juice or 1½ teaspoons citric acid to 1 pint water. Steam whole mushrooms—5 minutes; buttons or quarters—3½ minutes; slices—3 minutes; or saute in butter—4 minutes.
Use young, fresh, tender, sweet peas. Wash, then shell. Blanch 1½ minutes.
Use firm, crisp, thick walled. Wash and stem. No blanching necessary.
Use crisp, green, or red. Wash, remove seeds; cut in half, slice or dice. No blanching necessary. For easier packaging, may blanch halves 3 minutes, slices 2 minutes.
Use mature, not coarse or stringy. Wash, cut in pieces. Remove seeds. Cook until soft. Put through a sieve or in blender.
Use young, tender. Wash, peel, cut into ½-inch cubes. Blanch 2 minutes.
Spinach, Chard, Beet, Greens, Kale, Mustart or Turnip Greens
Use young, tender, green leaves. Wash thoroughly. Cut away thick woody stems. Blanch for 2 minutes.
Squash, Summer Zucchini, Yellow Crookneck
Use tender, before rind hardens. Wash, slice or dice into ½-inch pieces. Blanch 3 minutes.
Use well-ripened, with hard rind. Wash, cut into pieces. Remove seeds and membrane. Cook until tender. May be baked or steamed. Remove pulp from rind and mash. Cool.
Georgia C. Lauritzen and Charlotte P. Brennand Nutrition and Food Science