Title

Food Preservation: Drying Vegetables

(FN1588, Reviewed August 2022)
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Publication File:
Summary

Drying is a long-standing, fairly easy method of food preservation. Whenever you preserve foods, choose the best-quality fruits and vegetables. As with other food preservation methods, drying does not improve food quality. Proper and successful drying produces safe food with good flavor, texture, color and nutritional properties.

Lead Author
Lead Author:
Julie Garden-Robinson, Ph.D., R.D., L.R.D., Food and Nutrition Specialist
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Availability:
Web only
Publication Sections
Veggies ready for preservation

The following vegetables were rated as “excellent” or “good” by the University of Georgia for their quality after drying: carrots, sweet corn, garlic, mushrooms, onions, parsley, parsnips, peppers (all types) and potatoes. Many other vegetables may be dried, but the quality of the end product may not be as good as those listed. Tomatoes, for example, tend to absorb moisture easily, which can lead to color and flavor changes. 

Preparing Vegetables for Dehydration

Prepare vegetables for preservation immediately after picking to prevent color, flavor, texture, sugar content and nutrient changes. Sort and discard any food with decay, bruises or mold. Thoroughly rinse vegetables with running water, using a produce brush if necessary, then drain the vegetables well. Cut foods into c-inch to ½-inch slices. The higher the water content, the larger the slice size should be. Small slices of high-moisture foods would nearly disappear when all the moisture has evaporated.

To preserve quality and color, blanch prepared vegetables in boiling water or a citric acid solution for the times listed in Table 1. Blanching is a heating process that destroys enzymes, which can cause color and flavor issues. Water blanching achieves a more even heat penetration than steam blanching or microwave blanching. Citric acid acts as an anti-darkening and anti-microbial agent.

Procedure

If using citric acid (available in the canning section of the supermarket), stir ¼ teaspoon of citric acid into 1 quart of water. Citric acid helps prevent discoloration and acts as an anti-microbial agent.

  1. Fill a large kettle one-half to two-thirds full of water. Bring the water to a rolling boil.
  2. Place the vegetables in a wire basket, colander or mesh bag. You can blanch up to 1 quart of vegetables at a time.
  3. Submerge the vegetables in the boiling water, making sure the water covers the vegetables.
  4. As soon as the water reboils, start timing. Adjust the heat to ensure continuous boiling.
  5. Heat according to the time listed in Table 1.
  6. Submerge the container with the vegetables in cold water for the same amount of time as the blanching time).
  7. Drain the vegetables on paper towels.

Drying Vegetables

Drying is not a precise method of food preservation, and the amount of drying time will vary depending on the equipment, moisture content of the vegetables and the humidity in the air.

Spray a cookie sheet or similar flat tray with vegetable spray, or line the tray with plastic wrap or parchment paper and spray with vegetable spray. Another option is to use the specially designed plastic sheets for electric dehydrators, and follow the manufacturer’s directions.

Oven drying: Test your oven to be sure it can maintain a low enough temperature; otherwise, “case hardening” may occur. This is the formation of a “crust” on the food, which prevents the interior from drying properly.

To test your oven, set it to the lowest setting. Place an oven-safe thermometer on the rack where food will be placed. Leave the oven door open 2 to 6 inches. Place a fan near the open door to circulate air. Check the temperature. If your oven can maintain a low enough temperature (140 to 145 F), it may be used for food dehydration. Racks should be 2 inches apart, with at least 3 inches of clearance from the top or bottom to the rack. See Table 1 for approximate drying times.

Note: Oven drying is not a safe procedure to follow if young children are present.

Food dehydrator drying: Follow the manufacturer’s directions.

Testing for Dryness

Allow vegetables to cool prior to testing for dryness. Fully dried vegetables should be brittle or “crisp.”

Table 1: Steps for Drying Vegetables.

Vegetable

Preparation

Blanching Time (boiling water) (minutes)

Drying Time* (hours)

Dryness Test

Asparagus

Wash thoroughly. Halve large tips.

3½-4½

4-6

Leathery to brittle

Beans, green

Wash. Cut in pieces or strips.

2

8-14

Very dry, brittle

Beets

Cook as usual. Cool, peel. Cut into shoestring strips c inch thick.

None

10-12

Brittle, dark red

Broccoli

Wash. Trim, cut as for serving. Quarter stalks lengthwise.

2

12-15

Crisp, brittle

Brussels sprouts

Wash. Cut in half lengthwise through stem.

4½-5½

12-18

Tough to brittle

Cabbage

Wash. Remove outer leaves, quarter and core. Cut into strips c inch thick.

1½-2

10-12

Crisp, brittle

Carrots

Use only crisp, tender vegetables. Wash. Cut off roots and tops; peel. Cut in slices or strips c inch thick.

10-12

Tough to brittle

Cauliflower

Wash. Trim, cut into small pieces.

3-4

12-15

Tough to brittle

Celery

Trim stalks. Wash stalks and leaves thoroughly. Slice stalks.

2

10-16

Very brittle

Chili peppers, pimentos

Wash, stem, core. Remove “partitions.” Cut into disks about d by d inch. (Wear gloves if necessary.)

None

8-12

Crisp, brittle, medium green

Corn, cut

Husk, trim. Wash well. Blanch until milk in corn is set. Cut the kernels from the cob.

6-10

Crisp, brittle

Eggplant

Wash, trim, cut into ¼-inch slices.

3

12-14

Leathery to brittle

Garlic

Peel and finely chop garlic bulbs. No other pretreatment is needed. Odor is pungent.

None

6-8

Brittle

Horseradish

Wash, remove small rootlets and stubs. Peel or scrape roots. Grate.

None

4-10

Brittle, powdery

Mushrooms**

Scrub. Discard tough, woody stalks. Slice tender stalks ¼ inch thick. Peel large mushrooms, slice. Leave small mushrooms whole. Dip in solution of 1 tsp. citric acid per quart of water for 10 minutes. Drain.

None

8-10

Dry and leathery

Okra

Wash thoroughly. Cut into ½-inch pieces or split lengthwise.

None

8-10

Tough, brittle

Onions

Wash, remove outer paper skin. Remove tops and root ends, slice to ¼ inch thick.

None

3-9

Very brittle

Parsley, other herbs

Wash thoroughly. Separate clusters. Discard long or tough stems.

None

1-2

Flaky

Peas

Shell and wash.

2

8-10

Hard, wrinkled, green

Peppers, pimentos

Wash, stem. Remove core and seeds. Cut into ¼- to ½-inch strips or rings.

None

8-12

Tough to brittle

Potatoes

Wash, peel. Cut into ¼-inch shoestring strips or ½-inch-thick slices.

5-6

8-12

Brittle

Squash, summer or banana

Wash, trim, cut into ¼-inch slices.

10-12

Leathery to brittle

Squash, winter and pumpkin

Wash rind. Cut into pieces. Remove seeds and cavity pulp. Cut into 1-inch-wide strips. Peel rind. Cut strips crosswise into pieces about ¼ inch thick.

1

10-16

Tough to brittle

Tomatoes, for stewing

Steam or dip in boiling water to loosen skins. Chill in cold water. Peel. Slice ½ inch thick or cut into ¾-inch sections. Dip in solution of 1 tsp. citric acid/quart water for 10 minutes.

1

10-18

Crisp

**WARNING: Drying or cooking does not destroy the toxins in poisonous varieties of mushrooms. Only an expert can differentiate between poisonous and edible varieties.

*Drying times will vary depending on the moisture content of the food and the dehydrator being used. Oven-drying time may be twice as long.

Source: Table adapted from Colorado State University Extension, using University of Georgia blanching and drying times.

Packaging and Storing

Pack cooled dried vegetables in small amounts in dry glass jars (preferably with dark glass) or in moisture- and vapor-proof freezer containers, boxes or bags. Metal cans may be used if food is placed in a freezer bag first. Properly stored, dried vegetables keep well for six to 12 months. Discard all foods that develop off-odors or flavors or show signs of mold.

Using Dried Vegetables

Dried vegetables can be used in soups, dips, stews and sauces. When reconstituted, 1 cup of dried vegetables becomes 2 cups. When reconstituting leafy greens (kale, spinach), cover the dried vegetables with hot water and simmer to desired tenderness. When reconstituting root or seed vegetables (beans, corn, carrots), cover with cold water and soak for about an hour, then simmer until tender and use as desired.

For more information about growing, preserving and preparing fruits and vegetables, visit the NDSU Extension Service website

Sources

E.L. Andress and J.A. Harrison. 2006. So Easy to Preserve (5th Edition). University of Georgia Cooperative Extension Service.
J.A. Harrison and E.L. Andress. 2000. Preserving Food: Drying Fruits and Vegetables. University of Georgia Cooperative Extension Service.
P. Kendall, P. DiPersio and J. Sofos. 2004. Drying Vegetables. Colorado State University Extension.

Extension