Freezing produce is easy, quick and convenient. Freezing temperatures stop the growth of microorganisms while slowing down the chemical reactions that break food down and reduce quality. Properly frozen foods maintain more of their original color, flavor, and generally more nutrients than food preserved by other methods.
Blanching is a must for most vegetables to be frozen for long term storage. Blanching is a short heat treatment with boiling water or steam that slows or stops the enzyme action. Enzymes help the produce to ripen. Enzymes can still work slowly in a freezer causing loss of flavor, color, and texture. Blanching time is very important and varies with the vegetable and size.
- Under-blanching stimulates the activity of enzymes and is worse than no blanching.
- Over-blanching causes loss of flavor, color, vitamins and minerals.
Vegetables that do NOT need to be blanched are onions, peppers and tomatoes.
How to Blanch Vegetables
- 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 into boiling water. (Or steam blanch: boil 1-2 inches of water in a pot, bring to boil and then put a single layer of vegetables in basket above the water.)
- Cover. Start counting blanching time as soon as water returns to a boil. Or if steam blanching, start counting immediately.
- Keep heat high for the time given in the directions.
- Cool immediately in ice water or cold water (60 °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. Pack the vegetables either by dry pack or tray pack.
- Dry Pack: Pack vegetable tightly into containers or freezer bags. Press out air and seal tightly. Label with date and product. Freeze.
- Tray Pack: Put a single layer of the vegetable on a shallow pan and put the pan into the freezer. As soon as the vegetable is frozen, put them into a freezer bag or container. Press out air and seal tightly. Label with date and product. Place back in freezer for storage.
Frozen vegetables will maintain high quality for 8 to 12 months at 0° F or lower.
|Vegetable||Size of Pieces||Minutes in Boiling Water|
|Beans - snap, green or wax||2 to 4-inch lengths||3|
|Broccoli - flowerets||1 ½ inches across||3|
|Carrots||Diced, sliced or strips||2|
|Corn - whole kernel or cream style||Blanch before cutting corn from cob||4|
Select high quality, fresh, firm fruit. Wash and prepare just before freezing. Work in small quantities. Do NOT use galvanized, copper, or iron equipment. Fruit for freezing can be prepared in three different ways: dry pack, sugar pack and syrup pack. Although sugar can be omitted or artificial sweetener can be used, most fruit will have a better texture and flavor if packed in sugar or a sugar syrup.
- Dry Pack: Wash fruit, pack into a container and freeze. Tray pack method will allow smaller amounts to be used from frozen package. Used for small whole fruits, like berries.
- Sugar Pack: Wash fruit. Sugar is sprinkled over fruit, gently mixed, allowing juice to be drawn out of fruit before freezing. Used for peaches, strawberries and cherries.
- Syrup Pack: Sugar is dissolved in hot water, then cooled. Place washed fruit in a container and pour cooled syrup over it. A syrup pack is commonly used on fruit for uncooked desserts. The proportion of sugar to water depends upon the sweetness of the fruit to be frozen.
Discoloration: Peaches, apples, pears and apricots darken quickly and can lose flavor when exposed to air and during freezing. Using ascorbic acid, citric acid or lemon juice can lesson discoloration. They are used by adding to syrups or sugar before putting on fruit, dissolved in water and sprinkled on fruit, or dipping the fruit in the solution. Steaming can also be used to prevent discoloration on some fruits.
To protect the flavor, color, moisture content and nutritive value of food, pick freezer containers that are:
- Moisture vapor resistant
- Durable and leakproof
- Not brittle at low temperatures
- Resistant to oil, grease, and water
- Protects foods from absorbing odors
- Easy to seal
- Can be labeled
Freezing, National Center for Home Food Preservation
Vegetable blanching directions and times for home freezer storage, University of Minnesota Extension
This article was written in 2022 and has been peer-reviewed.