For thousands of years, people have dried vegetables to put them up for leaner times. Preserving foods by drying is still quite useful. It's convenient, inexpensive and requires less storage space than traditional canning.

Drying preserves food by removing a sufficient amount of moisture (water) from it to prevent it from decaying. This drying requires a method of heating the food (which allows moisture to evaporate) and some means of removing the water vapor which is formed (to keep the foods dry). This is where the term 'dehydration' comes from, the removing of water. Drying time will depend on the vegetable selected and how it is prepared.

Selecting Produce

In order to get the best results, select produce which is mature, yet tender and which have the characteristic color, flavor, and texture you desire. Wilted or inferior vegetables will not make a satisfactory dried product. Beware of overmature vegetables, as they will be tough and fibrous, or soft and mushy.

After gathering your vegetables, begin immediately to prepare them for drying. A good rule of thumb is that all vegetables should proceed from the garden to the drying tray within 2 hours. Make sure you wash the vegetables gently but thoroughly to remove dirt and insecticides. Wash them before you cut, shell or snap them. Sort and discard any that have decay, bruises or bad spots. Most vegetables will need to be pared, trimmed, cored, cut, sliced or shredded. Try to keep pieces uniform so they will dry evenly, and at the same rate. Take time to pretreat them for added appeal.

Pretreating For Health & Aesthetics

Pretreating is a step you should try hard to never skip. The time invested in this step will pay for itself in added visual appeal of the food and in increased nutritional benefits.

The enzymes in vegetables are responsible for color and flavor changes during ripening. These changes will continue during drying and storage unless the produce is pretreated to slow down enzymatic activity.

Blanching is the recommended pretreatment for vegetables. It helps save some of the vitamin content, sets the color, and hastens drying by relaxing tissues. Blanching may also prevent undesirable changes in flavor during storage and improve reconstitution during cooking.

You can blanch by steaming or immersing the vegetable in boiling water. Steaming allows the vegetable to retain more of the water-soluble nutrients, but it takes a little longer than immersing.

Here are detailed instructions how to do both:

Steam-blanching. Use a deep kettle that has a tight-fitting lid and a wire basket, colander, or sieve placed so that steam can circulate freely around the vegetables. Layer the vegetables loosely in the basket no more than 2 inches deep. Add 2 inches of water to the kettle and bring to a rolling boil. Place the basket of prepared vegetables in the kettle. The water should not come in contact with the vegetables. Cover tightly with the lid and steam until each piece is heated through and is wilted. Test by removing a piece from the center of the container and pressing it. It should feel soft but not completely cooked. Drain vegetables on paper towels or clean cloths.

Water-blanching. Use a deep kettle that has a tight-fitting lid. Fill full of water and bring to a vigorous boil. Place the vegetables in a wire basket or colander and submerge them in the boiling water. Work with small quantities only. The water should not stop boiling. Cover tightly with the lid. Remove the vegetables, dip in ice water to cool, and drain on paper towels or clean cloths.

Drying Foods: Basic Training

There are several ways you can dry produce. Drying in the kitchen oven or in a dehydrator is recommended; however, you can also use the sun to dry food under proper conditions.

Make sure you arrange the pretreated vegetable pieces in a thin layer on the drying trays, leaving a little space between pieces for air circulation. Dry pieces of similar size on the same tray.

Successful drying depends on the having following 3 conditions met:

• Enough heat to draw out moisture but not so much to cook the food. Hot sunny days are best for sun drying. Low oven heat, about 140 °F, dries it even faster. Do not let the heat go above 165 °F.
• Dry air to absorb the released moisture. Rainy, humid weather is a bad time to dry food unless you are using heat...and,
• Good air circulation to carry the moisture off. A light breeze, a fan, or a draft supplies moving air.

With these 3 conditions in mind, let's look at 3 methods to dehydrate or dry your foods, both the pro's and con's:

Sun drying. Drying vegetables in the sun is unpredictable unless temperatures are above 100 °F and the relative humidity is low. If the temperature is too low, humidity too high, or both, souring or molding may occur. Place trays of pretreated vegetables in direct sun in a flat or tilted position so that air can circulate underneath them. To keep out insects, cover trays with netting. Raise trays off the ground to protect them from dust, dirt and animals. Stir the vegetables occasionally to help them dry evenly. Bring trays indoors at night to protect the food from dew or rain.

Oven drying. Oven drying is faster than sun drying. However, oven drying is done on a smaller scale and is more expensive. Limit oven load to 4 to 6 pounds of prepared vegetables. Trays should be at least 1½ inches smaller than the width and depth of the oven. Separate trays by about 2 inches. Allow a 3-inch clearance from the top and bottom of the oven. An oven temperature of 140 °F is desirable for drying. Disengage the top heating element of an electric oven. Preheat the oven at its lowest setting. Place the trays of vegetables in the oven. Prop open the door of an electric oven 1 inch, a gas oven, 8 inches. This helps control heat and lets out moist air. A fan can help circulate the air and speed the drying. Use an oven thermometer to check the temperature throughout the drying process. As food dries it takes less heat to keep the oven at the specified temperature. Stir the vegetables occasionally from the outside to the center and shift the trays from top to bottom every 1 to 2 hours. Foods dried in the oven must be watched closely. It is easy to scorch vegetables that overheat near the edges of trays. When drying is almost completed, turn off the oven and open the door wide. Most vegetables will oven dry in 4 to 12 hours. Times will vary according to the kind of vegetable, size of the pieces, and the tray load.

Dehydrator drying. Prepare foods and load trays as for oven drying. Preheat the dehydrator to 160 °F. After much of the water has been removed, lower the temperature to 130 °F to 140 °F.

Testing for Dryness

Cool the food before testing for desired dryness. Foods that are warm or hot seem softer, more moist, and more pliable than they will when cooled. Foods should be dry enough to prevent microbial growth and subsequent spoilage. Dried vegetables should be hard and brittle.

Conditioning & Pasteurizing

When drying is completed, small pieces will be drier than large pieces, even on the same tray. When dried in the oven or dehydrator, some food dries faster in some spots on the tray. To condition or equalize the moisture, place the dried vegetables in a glass or plastic container or crock. Cover tightly and let stand for a week. Stir or shake the vegetables everyday. If there is evidence of moisture, return them to the drying trays and heat in a 150 °F oven for 30 minutes. Cool and package.

Pasteurizing is recommended when vegetables are sun dried. Insects may have gotten on foods dried outdoors and may cause spoilage. To pasteurize, spread the dried vegetables on trays in a single layer. Place in a preheated oven, 175 °F for 15 minutes or at 160 °F for 30 minutes. Remove and cool. You may also pasteurize vegetables by sealing them in heavy plastic bags and placing the bags in the freezer at 0 °F for at least 48 hours.

Packaging

Cool vegetables before packaging. Package dried vegetables in small quantities you can use within one week after opening. Every time you open the container, you expose the food to air and humidity, and the quality deteriorates. Small glass jars, metal cans with tight lids, plastic freezer cartons, and plastic freezer bags that you can seal with heat, twist tapes, string, or rubber bands all make good containers. Scald and dry them thoroughly. Pack the dried food into the container as tightly as possible without crushing and seal to keep out moisture.

Storing

Store containers of dried vegetables in a dry, cool, and dark place. Low storage temperatures extend the shelf life of the dried product. Check vegetables occasionally to insure that moisture has not been reabsorbed. If moisture occurs, reheat the food to 150 °F for 15 minutes, then cool and reseal. If there is any sign of spoilage (off-color or mold growth), discard the food. Recommended storage time is 6 to 12 months.

Cooking

Water removed during drying must be replaced either by soaking, cooking, or a combination of both. Soak root, stem, and seed vegetables for ½ to 2 hours in enough cold water to keep them covered. After soaking them, simmer until tender, allowing excess water to evaporate.

Greens, cabbage, and tomatoes do not need to be soaked. Simply add enough water to keep them covered, and simmer until tender.

Many vegetables lose their fresh flavor during drying. For this reason, you may add flavoring such as basil, garlic, onions, and chili sauce during cooking to improve flavor.

Dehydrated vegetables are usually not used as cooked side dishes. They are best when used as ingredients for soups, casseroles, sauces, stuffings, and stews. You may use various combinations of dried vegetables, but be careful not to add too much dried onion or garlic.