Freezing vegetables is a simple and quick method of preservation. Freezing costs more than canning or drying because of freezer purchase and operating costs, but it preserves more nutrients and fresh flavor if done properly.
Freezing slows the growth of microorganisms (bacteria, molds, yeasts) that cause food spoilage or illness. As soon as food is thawed, microorganisms will continue to grow. Freezing also slows chemical changes that affect quality. Natural enzymes in vegetables cause flavor, color, texture, and nutritive value changes. Freezing slows enzyme activity but does not stop it. Correct handling of vegetables is important before freezing.
Selecting and Washing Vegetables
Choose young, tender vegetables to freeze. Overmature vegetables might be hard, tough, or flavorless.
To remove dirt, wash thoroughly in cold water before using. This step can also reduce bacteria and pesticide residue. Do not use soap, detergent, or bleach because these liquids absorb into the vegetable. Drain and rinse several times. Peel, trim, and cut into pieces as directed for each vegetable in Table 1.
Blanching Vegetables
Blanching is essential for quality frozen vegetables. The blanching of vegetables before freezing inactivates the enzymes that impact product quality. Blanching also makes vegetables such as broccoli or spinach more compact, thus taking up less room in the freezer. Vegetables are briefly exposed to boiling water or steam and then rapidly cooled in ice water to stop cooking. Change water frequently or use cold running water or ice water. Recommended guidelines for blanching times are used to ensure the vegetables are not overcooked and do not lose flavor, texture, color, and nutrients. Under-blanching will cause enzymes to continue ripening the food. Refer to Table 1 for blanching times.
Boiling Water Blanch
Use 1 gallon of water per 1 pound of vegetables (2 gallons for leafy greens). Place vegetables in a wire basket or mesh bag; immerse in boiling water. Cover. If water does not return to a boil within 1 minute, you are using too many vegetables for the amount of boiling water. Begin blanching time as soon as the water returns to boil.
Steam Blanch
Place one layer of vegetables in a wire basket. Suspend in a steamer above several inches of rapidly boiling water and cover. Begin steaming time when the lid is on—steam 1½ times longer than the boiling water blanch time.
Microwave Blanch
Microwave blanching is not recommended as it produces uneven results because of the varied heat patterns within a microwave oven. Microwave blanching requires working with only small quantities at a time; there is no time saved when working with large quantities of vegetables.
Packaging Vegetables
Air leads to flavor loss or off-flavors. If moisture evaporates, frozen food becomes dry and tough and might develop grayish spots called "freezer burn."
Foods for the freezer should be appropriately packed to protect their flavor, color, moisture content, and nutritive value.
Select packaging materials with these specific characteristics:
- food-grade (intended to be in contact with foods)
- moisture- and vapor-resistant
- durable and leak-proof
- resistant to oil, grease, and water
- not susceptible to becoming brittle and cracking at low temperatures
- able to protect foods from absorbing other flavors or odors
- easy to seal
- easy to label
Suitable packaging materials include rigid plastic containers with straight sides made for freezing, glass jars and lids made for freezing, and moisture-vapor-resistant bags. Disposable containers intended for short-term storage, such as bread bags, plastic yogurt containers, milk cartons, or ice cream tubs; regular aluminum foil; or waxed paper, do not protect against flavor and moisture loss or freezer burn during long-term storage. Before packing, allow the food to cool completely. Pack foods in quantities that are suitable for your intended use.
Packing Methods
Dry Pack: Package vegetables quickly. Squeeze air from the bags before sealing. Leave headspace in rigid containers to allow for expansion (½ inch for pint containers and 1 inch for quart containers). This allows for food expansion upon freezing.
Tray Pack: Freeze vegetable pieces in a single layer on a tray until frozen solid. Package immediately; long exposure will result in loss of moisture. Label and date the product and return it to the freezer.
Freezing
Because water in vegetables expands during freezing, which breaks cell walls, thawed vegetables may leak juices and be soft. To retain quality, freeze vegetables quickly at the lowest possible freezer setting. For best results, freeze only 2–3 pounds of vegetables per cubic foot of available storage space within 24 hours.
Storage
Maintain freezer at 0 degrees Fahrenheit or lower to best protect the quality of foods. Use a freezer thermometer to ensure accurate temperature. If power fails, keep the freezer closed. Food should stay frozen for 24 to 48 hours. Food can be safely refrozen if it still contains ice crystals. However, there is a possibility of a loss of quality and nutrients. Keep an inventory and use the oldest foods first. Use frozen vegetables within one year.
Serving Frozen Vegetables
Most frozen vegetables can be cooked without thawing; corn on the cob should be partially thawed. To maintain nutrients, cook vegetables in ½ cup or less water per pint package. Drain and season as desired.
Vegetables to Avoid When Freezing
Some vegetables do not make satisfactory products when frozen. These include cabbage, celery, cucumbers, lettuce, and radishes. These vegetables can be stored for short periods in the refrigerator.
Additional Resources
Note: This fact sheet uses language, recipes, procedures, and data from reliable sources such as the ones listed below. For the most part, the original text has been preserved because safety around food preservation is especially important. For safe and healthy preserved foods, be sure to carefully follow directions.
Learn more about freezing vegetables:
- Freezing Basics, HYG-5341
- Freezing Fruits, HYG-5349
- What To Do When Your Freezer Stops HYG-5357
- National Center for Home Food Preservation
Reference
Andress, E. L., Harrison, J. A., & Reynolds, S. J. (2014). So easy to preserve (6th ed.). Cooperative Extension, University of Georgia/Athens, College of Family and Consumer Sciences, College of Agricultural and Environmental Sciences. Reprinted 2020.
Original author, Sharon L. Mader, Extension Educator, Family and Consumer Sciences, retired. Revised May 28, 2015, by Bridgette Kidd, MPH, RD, former Healthy People Program Specialist, Family and Consumer Sciences.