Freezing is one of the easiest, most convenient, and least time-consuming methods of preserving foods. Freezing does not sterilize foods; the extreme cold simply retards the growth of microorganisms and slows down chemical changes that affect quality or cause food to spoil. You can freeze fruit, vegetables, meat, poultry, seafood, dairy, and even eggs if you follow reliable, tested methods. For example, blanching vegetables prior to freezing.
The National Center for Home Food Preservation recommends blanching vegetables before freezing to maintain quality. Basically, blanching involves scalding vegetables in boiling water or steaming for a certain amount of time, then cooling it in ice water, followed by draining and packaging. This process helps to stop enzyme activity, which can degrade the food’s flavor, color, and texture over time. Exceptions: Although blanching times are given, diced or cut onions, green onions, leeks and peppers do not need to be blanched before freezing.
Blanching time is important and varies with the vegetable and size of the pieces. Under-blanching stimulates the activity of enzymes and is worse than not blanching. Over blanched vegetables cause the loss of flavor, color, vitamins, and minerals.
Blanching Directions
- Wash, drain, sort, trim and cut vegetables.
- Use 1 gallon water per pound of prepared vegetables or 2 gallons water per pound of leafy greens.
- Put vegetables into blancher (wire basket, coarse mesh bag or perforated metal strainer) and lower it into boiling water. Or steam blanch: Add 1-2 inches of water to a pot and bring to boil then put a single layer of vegetables in the basket.
- Cover. Start counting blanching time as soon as water returns to a boil. If using steam blanching, the count starts immediately.
- Keep heat high for the time given in the directions.
- Cool immediately in ice water or cold water (60 degrees F or below) for the same time used in blanching (except for corn on the cob for which cooling time is twice the time of blanching). Stir vegetables several times during cooling.
- Drain vegetables thoroughly. Use a salad spinner for firm vegetables.
- Pack the vegetables either by dry-pack or tray-pack.
- Dry pack: Pack vegetables tightly into freezer containers or freezer bags. Press out air and seal tightly.
- Tray-pack: Put a single layer of vegetables on a shallow pan and put the pan into the freezer. As soon as the vegetables are frozen, put them into a freezer bag or container. Press out air and seal tightly.
- Freeze.
- Frozen vegetables will maintain high quality for 8 to 12 months at zero degrees F or lower.
Resources and Sources
Freezing Vegetables [fact sheet], UNH Extension - information, including a chart of instructions and blanching times for individual vegetables.
Freezing Fruit [fact sheet], UNH Extension - information and instructions for individual fruits.
Freezing, The National Center for Home Food Preservation - detailed information on freezing multiple different items and background information on freezing. Follow the links on the left-hand side of the webpage.
