Blanching and Freezing Vegetables - How-to-Guide
When you have an oversupply of vegetables, freezing them can extend their shelf-life until the time that you need them in your recipes. Most vegetables can be frozen, however, there are some which are not to be frozen like lettuce, salad greens, green onions, cucumbers, celery, tomatoes and radishes. These lose crispness and texture when frozen.
Unlike freezing meat and poultry, fresh vegetables need an extra step called blanching in its preparation before freezing. Blanching destroys enzymes in the food that can speed up chemical changes that can give food a disagreeable odor or flavor or a different color. If these enzymes are not destroyed, they can continue to operate even at freezing temperature. So, by blanching the fresh flavor and appearance of the vegetables are retained.
According to the National Center for Home Food Preservation, there are three ways of blanching vegetables: Water blanching, Steam blanching and Microwave blanching. Water blanching is best for most vegetables. Those that can be blanched either by water or steam blanching are broccoli, sweet potatoes and winter squash.
- Water blanching. Immerse in rapidly boiling water the prepared fresh vegetables placed in a wire-mesh basket. Cover and boil (refer to specific vegetable list below for recommended boiling time). Allow 1 minute more boiling time at 5,000 or more feet above sea level.
- Steam blanching. Bring to boil 1-2 inches of water in a pot with a tight lid and a basket that holds the food at least three inches above the bottom of the pot. Place the vegetables in the basket in a single layer. Cover and steam for the recommended blanching time (see below).
- Microwave blanching is not as effective as the above methods as it may not fully deactivated all enzymes present in the vegetables. For microwave blanching, use small quantities and follow specific microwave oven instructions.
Remove promptly the blanched vegetables as soon as the time is up. Then give the fruits a cold or icy water bath. Cool for the same number of minutes as they were blanched. This stops the vegetable from being cooked further by the absorbed heat from blanching.
General Guidelines for Freezing Vegetables
Selection: Fresh, tender vegetables should be chosen. The quality of the vegetables before freezing will affect the quality of the frozen vegetables.
Preparation: Wash, trim and sort vegetables according to size. Then blanch the vegetables (See the instructions on the left).
Packaging: Use airtight containers for packing the vegetables. Rigid containers like glass, aluminum, plastic or heavily waxed cardboard can be used. Moisture-vapor proof freezer bags are also suitable. When filling the containers, leave a 1/2-inch headspace between the vegetables and the top of the container. This gives the food some room to expand.
Labeling and Storage: Label the package with the contents and date of packaging. Freeze at 0oF or below in small batches. This can be kept up to 8-12 months.
Thawing or Cooking instructions: Pour the wanted quantity of frozen vegetables into a pot of boiling water. Use enough water to cover the vegetables. Add a little salt if you wish. Bring the water to boil again and cook for 3-5 minutes. Drain the water and the vegetables are ready to be served or to be added as the last ingredient in your recipe. If the vegetables have been defrosted in its packaging, the cooking time should be reduced accordingly. DO NOT REFREEZE once defrosted.
How to Freeze Raw Vegetables Video
Freezing Specific Vegetables
- Wash. Trim, cut to desired length or in 2-inch pieces. Sort according to stalk thickness. Water blanch small stalks for 2 minutes and large stalks for 4 minutes. Cool, pack, seal, label and freeze.
Freezing Green Beans and Lima Beans
- Wash the green beans. Remove ends and cut to desired length. Water blanch for 3 minutes. Cool, pack, seal, label and freeze.
- Shell the lima beans or leave in pods and shell after blanching. Water blach small pods for 2 minutes and large pods for 4 minutes. Cool, pack, seal, label and freeze.
- Wash and sort according to size; leave 1/2 inch stems. Cook till tender. Peel and cut up. Water blanch small beets for 25-30 minutes and medium beets for 45-50 minutes. Cool, pack, seal, label and freeze.
- Wash, peel stalks, trim and cut into medium pieces (5-6 inches long), no thicker than 1 1/2 inches. Water blanch for 3 minutes or steam blanch for 5 minutes. Cool, pack, seal, label and freeze.
- Wash and pare. Cut into 1/4-inch slices or leave whole for baby carrots. Water blanch sliced carrots for 2 minutes and baby carrots for 5 minutes. Cool, pack, seal, label and freeze.
- Wash and cut into 1-inch pieces. Water blanch for 3 minutes. Cool, pack, seal, label and freeze.
Freezing Sweet Potatoes
- Cook till almost tender - about 30-40 minutes by boiling or 45-60 minutes by steaming. Cool, pare and slice. Dip in a solution of 1/4 cup lemon juice to 1 quart water. Alternatively, you can mash and mix 2 tablespoons lemon juice with each quart. Cool, pack, seal, label and freeze.
- Wash summer squash and cut in 1/2-inch slices. Water blanch for 3 minutes. Cool, pack, seal, label and freeze.
- Cut winter squash into pieces. Remove the seeds and cook by boiling for 15 minutes or 20 minutes by steaming until soft. Remove the pulp and mash. Cool quickly. Cool, pack, seal, label and freeze.
For blanching time of other vegetables, please refer to National Center for Home Food Preservation.