Blanching: Critical Step for Frozen Vegetables

Blanching, or scalding, is a critical step in preparing fresh vegetables for freezing. This process cleanses the vegetable surfaces of dirt and organisms, brings up their color, helps retain vitamins and reduces the action of enzymes that otherwise would destroy their fresh flavor after about a month in the freezer.

The fresher the vegetables are when frozen, the more satisfactory the end product. Choose those at their peak of ripeness and process them as soon as possible.

Freezing retards the growth of bacteria but does not sterilize the food. Therefore, sanitary measures in the handling and processing of foods are very important.

Before blanching, wash, drain, sort, trim and cut the vegetables the same as you would if you were cooking them fresh. Use one gallon of water to blanch each pound of vegetables--two gallons for a pound of leafy greens.

It’s All in the Timing

Place the vegetables in a wire basket and lower it into vigorously boiling water (Step 1). Begin counting the blanching time as soon as the vegetables enter the water. Keep the heat on high and stir the water or cover the container during blanching.

Time the blanching carefully, using the following chart. Under-blanching stimulates enzyme activity rather than reducing it; prolonged scalding causes loss of vitamins, minerals, flavor and color.

Remove the vegetables from the boiling water and immediately plunge into ice water (Step 2) to stop the cooking process. Stir the vegetables as they cool for approximately the same amount of time they were blanched. If more than one batch of vegetables is being prepared, the hot vegetables may be poured into a colander set in the ice water so the wire basket can be reused.

Airtight Packaging

Pack the cooled vegetables loosely into moisture-and-vapor-proof containers (Step 3). Seal, label with the contents and date (Step 4), then place the containers in a single layer in the freezer, leaving about one inch of space between the packages so they freeze quickly. Once completely frozen, packages may be compactly stacked. Frozen vegetables should be used within one year.

When large quantities of vegetables are being processed, determine the amount that can be blanched in 15 minutes and keep the remainder under refrigeration until the first batch has been packaged. The same scalding water may be reused for the same product, adding water as needed to retain the proper level.

The following timetable for blanching vegetables prior to freezing comes from the “Handbook of Food Preparation,” published by the American Home Economics Assn.

Asparagus Small stalks--2 minutes Medium stalks--3 minutes Large stalks--4 minutes

Beans, lima Small beans or pods--2 minutes Medium beans or pods--3 minutes Large beans or pods--4 minutes

Beans, green or wax--3 minutes

Beets Small--25 to 30 minutes Medium--45 to 50 minutes

Broccoli florets (1 1/2 inches)--3 minutes

Brussels sprouts Small heads--3 minutes Medium heads--4 minutes Large heads--5 minutes

Cabbage, coarse shreds or thin wedges--1 1/2 minutes

Carrots Small whole--5 minutes Diced, sliced, strips--2 minutes

Cauliflower, 1 inch pieces--3 minutes

Celery, 1 inch lengths--3 minutes

Corn, sweet, on the cob Small ears (1 1/4-inches or less in diameter)--7 minutes Medium ears (1 1/4 to 1 1/2 inches in diameter)--9 minutes Large ears (over 1 1/2 inches in diameter)--11 minutes Whole kernel and cream style--4 minutes (cooking time before kernels are cut off cob)

Greens Beet, chard, kale, mustard, spinach, turnip--2 minutes Collards--3 minutes

Kohlrabi 1/2-inch cubes--1 minute Whole, small to medium in size--3 minutes

Okra Small pods--3 minutes Large pods--4 minutes

Parsnips, 1/2-inch cubes or slices--2 minutes

Peas Black-eyed--2 minutes Green--1 1/2 minutes

Peppers Halves--3 minutes Slices--2 minutes

Pumpkin--until soft

Rutabagas, 1/2-inch cubes--2 minutes

Squash Tender-skinned--3 minutes Hard-shelled--until soft

Sweet potatoes--until almost tender

Tomato juice (simmer tomatoes)--5 to 10 minutes

Turnips, 1/2-inch cubes--2 minutes

Note: It is not necessary to blanch rhubarb, peppers, onions and herbs used exclusively for flavoring.

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