Martha Archuleta, Food and Nutrition Specialist
College of Agriculture, Consumer and Environmental Science, New Mexico State University.
Fresh vegetables can be frozen quickly and easily during the harvest season. Whether you freeze purchased or home-grown vegetables, the keys to a successful product are using vegetables at the peak of ripeness and freezing quickly after purchase or harvest.
Selection and Purchase
Choose vegetables that are young and tender. Wash well and rinse twice in fresh water each time to remove dirt. Trim away any bad areas, tough stems, and leaves. Cut into desired sizes.
Although freezing slows enzyme action, it doesn’t completely halt it. Blanching, a heat treatment to inactivate the ripening enzymes in vegetables, preserves their color, texture, and flavor for nine to twelve months in the freezer.
Except for onions and green peppers, vegetables should be either water or steam blanched before being frozen. Some vegetables, such as mushrooms, eggplant, and summer squash, taste better if sauteed briefly in oil, butter, or margarine before freezing. Chill before packing.
To water blanch vegetables, place the washed, prepared vegetables in a pot of boiling water. Use one gallon of water for each pound of prepared vegetables. See table 1 for recommended blanching times for different vegetables. Start timing the blanching action when the water returns to boiling after putting in the vegetables. Plunge the vegetables immediately into cold (preferably ice) water for the same time as you blanched the vegetable. This cold bath stops the cooking action.
To water blanch, place two cups or about 1 pound of prepared vegetables in a single layer in a basket and lower into a pot containing one gallon of boiling water. The vegetables should be above the water. Cover with tight-fitting lid and start counting blanching time when steam comes up around the pot lid. (See table 1 for blanching times.) Plunge vegetables into a cold bath.
You can use the microwave oven to blanch small quantities. However, there is no time or money saved when microwave blanching vegetables.
Packing Food into Freezer Containers
Drain and chill food before packing into moisture proof freezer containers. Both freezer bags and square containers provide economical packs with regard to space used in the freezer.
Fill rigid containers to the expansion line. If you use freezer bags, lay bags on counter after filling with drained vegetables and press out air. Close zipper bags except for about one inch. Use a drinking straw to suck air out and complete closure. If using a bag with a twist tie closure, gather edges around drinking straw and draw out air before twisting and tying.
Date and identify contents using a moisture proof freezer pen. When freezing, place packages in the coldest area of the freezer with about one inch around the packages for cold air circulation until the food is frozen. After packages are frozen, stack tightly.
Freeze only the amount that the freezer can handle efficiently. A good rule of thumb is 2 to 3 pounds of food for each cubic foot of storage space. Overloading slows the freezing process and adversely affects the quality of the food, especially corn-on-the-cob.
Make a food inventory and post it close to the freezer. List foods and number and sizes of containers. Keep a pen close to mark the list as cartons are used.
Thawing and Preparing Vegetables to Eat
Except for corn-on-the-cob, vegetables can be cooked with little or no thawing. Corn on the cob should be thawed completely before cooking. Greens should be partially thawed and separated before cooking. Because the vegetables were blanched before freezing, they will cook quickly.
Use the smallest amount of water possible to conserve nutrients. Cook only the amount you need for the meal. Avoid letting vegetables stand after cooking as nutrients leach into the cooking water.
Table 1. Freezing Techniques for Vegetables
|Asparagus||Wash, sort by size. Snap off tough ends. Cut stalks in 2-inch lengths or leave in spears.||Water blanch:
Small stalks: 1-1/2 min.
Medium: 2 min
Large: 3 min.
Small: 2-1/2 min.
Medium: 3 min
Large: 4 min.
|Beans||Wash. Trim ends. Cut if desired.||Water blanch:
Whole: 3 min.
Cut: 2 min.
Whole: 4 min.
Cut: 3 min.
|Beets||Wash. Remove tops leaving 1 inch of stem and root||Cook until tender: for small beets, 25–30 minutes; for medium beets, 45–50 minutes. Cool promptly, peel, trim tap root and stem. Cut into slices or cubes. Pack into freezer containers.|
|Broccoli||Wash. Trim leaves. Cut into pieces.||Water blanch 3 min.||Steam blanch 3 min.|
|Brussels sprouts||Wash. Remove outer leaves.||Water blanch 4 min.
|Steam blanch 5 min.|
|Cabbage||Wash. Discard course outer leaves.||Water blanch:
Wedges: 3 min.
Shredded: 1-1/2 min.
Wedges: 4 min.
Shredded: 2 min.
|Carrots||Wash, peel and trim. Cut if desired; leave small carrots whole.||Water blanch: Whole: 5 min.
Sliced : 2 min.
|Cauliflower||Discard leaves and stem, wash. Break into flowerets or leave small heads whole (no more than 4-inch diameter).||Add 1 Tbsp. vinegar to water.
Water blanch: Whole: 6 min.
Cut: 3 min.
|Add 1 Tbsp. vinegar to water.
Steam blanch: Whole: 7 min.
Cut: 4 min.
|Corn||Remove husks and silks and trim ends.
|Water blanch medium-sized ears, 3-4 ears at a time, 5 min. After blanching, cut kernels (about 2/3 depth) from cob, bag kernels, freeze.|
|Corn on the cob||Remove husks and silks and trim ends.
|Water blanch medium-sized ears, 8 min. Cool. Drain. Wrap ears individually in plastic wrap. Pack wrapped ears in plastic freezer bags.|
|Eggplant||Wash, peel, slice 1/3 inch thick.||Water blanch 4 min. in 1 gallon of boiling water containing 1-1/2 Tbsp. citric acid or 1/2 c. lemon juice. Or, saute in oil and pack.|
|Greens||Select young, tender greens. Wash.
|Water blanch 2 min., or steam blanch 3 min. Avoid matting woody stems.|
|Herbs||Wash. Snip or leave on stalks.||For basil only, water or steam blanch 1 min. For other herbs, blanching is not necessary. Freeze in a single layer on cookie sheet.|
|Kohlrabi||Select tender, mature stems. Trim ends.
Wash. Peel off tough bark. Wash. Slice
tender centers crosswise, 1/4 inch thick.
Leave small roots whole.
|Water blanch slices for 2 min., stems for 3 min.|
|Mushrooms||Wipe with damp paper towel. Trim hard
tip of stems. Sort; cut large mushrooms.
|May be frozen without blanching. Or, blanch whole, 5 min.; quarters, margarine, 3-1/2 min.; slices, 3 min. Or, saute mushrooms in butter or cool quickly, and pack.|
|Okra||Wash. Separate pods 4 inches and shorter from longer pods. Remove stems.||Water blanch small pods, 3 min.; large pods, 5 min.|
|Shell garden peas. No need to shell snow or sugar peas.||Water blanch 1-1/2 min., or steam blanch 2-1/2 min.|
|-For onions, remove peel and chop.
-For green onions, trim and slice or leave whole.
-For leeks, make a cut through leaves and bulb.
Do not cut roots. Wash thoroughly.
Trim tops. Leave whole or slice.
|May be frozen without blanching. Bag and Freeze. (For best odor protection, wrap onions in plastic film before putting in bags.)|
|Wash, remove stems and seeds.||Freeze whole, or cut as desired. No heat treatment needed.
(See Guide E-311, Freezing Green Chile.)
|Potatoes||Peel, cut, or grate as desired.||Either cook in water or saute grated potatoes in oil. Grated potatoes for hashbrowns and mashed potatoes freeze well. For new potatoes, blanch whole potatoes 5 min., blanch pieces 2-3 min.|
|Sweet potatoes||Wash and dry.||Bake just until tender; cool. Peel and cut. Pack in flat layers or roll in lemon juice and brown sugar. Or, puree with orange juice.|
|Wash and remove seeds||Bake whole or cut in half. Place cut side down on baking sheet. Cook until tender. Scrape pulp from rind, or remove rind and cube. Cool Pumpkin and freeze cubes, or mash pulp, cool, and pack.|
|Wash, trim ends. Cut into slices or strips.||Water blanch 3 min. or steam blanch 4 min. and freeze also be breaded and sauteed in oil. Cool and freeze. For sauteed sqaush, place waxed paper between slices before freezing.|
Originally written by Alice Jane Hendley, Food and Nutrition Specialist.
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Revised and electronically distributed January 2003, Las Cruces, NM.