Freezing Vegetables Fact Sheet No. 9.330 Food and Nutrition Series|Preparation by P. Kendall* Freezing is an excellent way to Selecting and Quick Facts preserve fresh vegetables. The quality of Preparing Vegetables frozen vegetables depends on the quality • The quality of frozen Use vegetables at peak flavor and of the fresh products and how they are vegetables depends on texture. When possible, harvest in the handled from the time they are picked the quality of the fresh cool part of the morning and freeze until they are ready to eat. It is important produce. within two hours. Wash vege tables to get the product from the garden to the thoroughly in cold water, lifting them out freezer in as short a time as possible. It is • Blanching and prompt of the water as grit settles to the bottom important, also, to start with high-quality cooling are essential of the washing con tainer. Sort by size for vegetables, as freezing will not improve in preparing most blanching and packing. the product’s quality. vegetables, ex cept herbs Blanching and prompt cooling are and green peppers, for necessary steps in preparing practically Blanching Vegetables freezing. every vegetable, except herbs and green Most vegetables may be blanched in • Blanch vegetables by peppers, for freezing. The reason is boiling water or steam. placing them in boiling that heating slows or stops the enzyme water or steam. action. Enzymes help vegetables grow and mature. After maturation, however, Blanching in Boiling Water • There are two basic they cause loss of quality, flavor, color, To blanch vegetables in boiling packing methods texture and nutrients. If vegetables are water, bring at least 1 gallon of water to recommended for frozen not heated enough, the enzymes continue a rapid boil in a blancher or large kettle vegetables: dry pack and to be active during frozen storage and with a lid. Lower a pound of pre pared tray pack. may cause the vegetables to toughen or vege tables placed in a metal basket or develop off-flavors and colors. Blanching cheesecloth bag into the boiling water • Most vegetables maintain also wilts or softens vegetables, making and cover with a lid. Start counting high quality for 12 to 18 them easier to pack. It destroys some time as soon as the vegetables are in the months at 0 degrees F. bacteria and helps remove any sur face boiling water. Keep heat on high for the dirt. total blanching time specified in Table 1. Follow the recommended blanching Selecting Freezing time for each vegetable. Under-blanch ing may stimulate enzyme activity and could Containers be worse than no blanching. Prolonged Select containers best suited to blanching causes loss of vitamins, the vegetable. Square or rectangular minerals, fla vor and color. flat-sided containers make the best use of freezer space. Good quality Steam Blanching moisture- and vapor-proof packaging materials made of glass or rigid plastic Heating in steam is another way to are best. They prevent drying of the blanch vegetables. Steam blanching takes food during freezer storage. Moisture- somewhat longer than water blanching and vapor-resistant bags and waxed but helps retain water-soluble vitamins. © Colorado State University cartons designed for freezing also retain Steam-blanching times are given in Extension. 8/94. Revised 1/13. satisfactory quality. Table 1 for those vegetables that steam most successfully. www.ext.colostate.edu *P. Kendall, Ph.D., R.D., Colorado State University, associate dean of research, food science and human nutrition. 1/2013 To steam vegetables, bring 1 to 2 lightly sautéed in butter or margarine, labeled bags or containers. Close and inches of water to a rolling boil in a then cooled and dry packed. Stewed freeze immediately. Tray-packed foods kettle with a tight-fitting lid and a tomatoes may be prepared ahead, do not freeze in a block but remain rack that holds a steaming basket or then frozen in meal-size portions. See loose so that the amount needed can cheesecloth bag at least 3 inches above specific directions in Table 1. be poured from the container and the the bot tom of the kettle. Put a single package reclosed. layer of vegetables in the basket or bag so steam can reach all parts quickly. Packing Methods Place the basket or bag on the rack in There are two basic packing Labeling and Storing the kettle, cover and keep heat on high. methods recommended for frozen Label packages with the name of the Start counting steaming time as soon as vegetables: dry pack and tray pack. product and the freezing date. Freeze the lid is on. To dry pack, place the blanched at once at 0 degrees F or lower. Because After vegetables are heated, cool and drained vegetables into meal-sized speed in freezing is impor tant for best quickly and thoroughly to stop the freezer bags or con tainers. Pack tightly quality, put only as much unfrozen cooking. To cool vegetables heated to cut down on the amount of air in veget ables into the freezer at one time in boiling water or steam, plunge the the package. Leave 1/2-inch headspace as will freeze in 24 hours, usually 2 basket of vegetables imme diately into at the top of rigid containers and close to 3 pounds per cubic foot of freezer a large quantity of cold water that is securely. For freezer bags, fill to within capacity. 60 degrees Fahrenheit (F) or below. 3 inches of top, twist and fold back For quickest freezing, place pack- Change water frequently or use cold top of bag, and tie with a twist tape or ages at least 1 inch apart against freezer running or iced water. Use about rubber band about 1/2- to 3/4-inch plates or coils. After vegetables are 1 pound of ice for each pound of from the food. This allows space for frozen, rearrange pack ages and store vegetables. It takes about as long to cool the food to expand. Provision for close together. Most vegetables main- the food as to heat it. When vegetables headspace is not necessary for foods tain high quality for 12 to 18 months are cooled, remove from the water and such as broccoli, asparagus and Brussels at 0 degrees F or lower. Longer storage drain thoroughly. sprouts that do not pack tightly in will not make food unfit for use, but containers. may impair quality. It is a good idea to To tray pack, place chilled, well- post a list of the frozen vegetables near Pre-Cooking Prior to the freezer and to check off pack ages as Freezing drained vegetables in a single layer on shallow trays or pans. Place in freezer they are used. Some foods are best preserved until firm, then remove and quickly fill by pre-cooking prior to freezing. Pumpkin, sweet potatoes and winter References squash may be heated in a microwave Table 1 Freezing of Vegetables, FDNS-E043-5. oven, pressure cooker or oven until soft, J.A. Harrison and E.L. Andress. then chunked or pureed or for storage On Next Page University of Georgia Cooperative in meal-sized portions using the dry Extension Service, Athens, GA, pack method. Mushrooms may be 2000. Table 1. Vegetable freezing guide. (Note: Blanching times given are for 5,000 feet or higher. At altitudes below 5000 feet, subtract one minute from times given.) Vegetable Preparation Asparagus Select young, tender stalks with compact tips. Remove or break off tough ends and scales. Wash thoroughly. Sort for size. Cut to fit containers or in 2-inch lengths. Blanch medium stalks 4 minutes in boiling water, 5 minutes in steam. Blanch large stalks 5 minutes in boiling water, 6 minutes in steam. Cool and drain dry. Pack without head space, alternating tips and stem ends of spears. Beans, green Select young, tender stringless beans. Wash thoroughly, remove ends, sort for size. Cut into 1- to 2-inch pieces, leave whole, or slice into lengthwise strips. Water blanch 4 minutes. Chill and drain. Dry pack with headspace, or tray pack. Beans, lima Select well-filled pods contain ing green beans. Wash, shell and sort. Water blanch 3-5 minutes, depending on size. Cool and drain dry. Tray pack or dry pack with headspace. Beans, green Select firm, well-filled, bright green pods. Wash. Water blanch 6 minutes. Cool and drain. Squeeze soybeans soybeans out of pods. Dry pack with headspace, or tray pack. Beets Select beets 3 inches in diameter or less. Wash; sort for size. Remove tops, leaving 1/2-inch stems. Cook in boiling water until tender: 25-30 minutes for small beets, 45-50 minutes for medium-sized beets. Cool and drain; peel, slice or cube. Dry pack with headspace. Broccoli Select tender, dark green stalks. Wash; peel and trim stalks. To remove insects from heads, soak 30 minutes in a solution of 4 teaspoons salt per gallon of water. Rinse and drain. Split lengthwise into pieces not more than 1 1/2 inches across. Blanch in steam 6 minutes or boiling water 4 minutes. Cool and drain. Dry or tray pack without headspace. Brussels sprouts Select green, firm, compact heads. Wash, trim. Soak in salt solution (see broccoli) 30 minutes to drive out insects. Rinse and drain. Water blanch 4-6 minutes depending on size of head. Cool and drain. Dry pack without headspace. Cabbage Wash. Trim coarse outer leaves of solid heads. Cut heads into medium or coarse shreds, thin wedges or separate into leaves. Water blanch 2 1/2 minutes. Cool and drain. Dry pack with headspace.