Posted by Janet Harriett on Aug.04, 2009

©iStockphoto.com - redtwiggy

Home food preservation helps you enjoy that bounty well after the season ends. Last week, I discussed freezing your produce to preserve your garden, farmer’s market or CSA produce. This week, I’ll discuss dehydrating.

Although dehydrating is most commonly associated with a narrow range of fruits like raisins, cherries, apples, apricots and cranberries, you can dehydrate nearly any type of fruit or vegetable. Dehydrated produce has the advantage of being shelf-stable at room temperature, and allows you to store a lot of produce in a small space. A pint jar can hold eight or more dehydrated bell peppers, and dehydrated produce, when stored properly without exposure to moisture, can keep for several years in a pantry. Dried food retains most of the nutrients, though some are lost with longer storage times.
The basic principle of dehydrating is to remove the water from food. Bacteria and other spoilage organisms require water, and when the moisture content of the food is below 10-15%, the organisms cannot thrive. To dehydrate, you simply cut the food into uniformly thick pieces and expose to 140F circulating air until most of the water evaporates out of the food. Store in tightly closed moistureproof containers.

Electric Food Dehydrators

Electric dehydrators give the most control, therefore the most consistent results. Electric food dehydrators have a box with mesh trays–some have solid liners for making fruit or vegetable leathers–with a heating element and a fan to circulate the warm air. Higher quality dehydrators have temperature controls, and some of the highest-end dehydrators even have timers to turn the unit off if the end of the dehydrating time comes when you’re asleep or at work. The electricity consumption is on par with an average incandescent lightbulb.

Simply arrange food on the included trays, set the temperature and let it go. You may need to rotate the trays every few hours, since electric dehydrators tend to have hot spots near the element and fan where food dries faster. Wash and dry trays thoroughly between loads.

In spite of the name, electric dehydrators aren’t one-trick appliances. High-quality dehydrators with adjustable temperature control can be used for rising bread or making homemade yogurt. Raw food cookbooks often include recipes for cookies or crackers made in a food dehydrator.

Oven

If you don’t have an electric dehydrator or want to try food drying out before getting a good-quality dehydrator, your oven can be used to dry food, though the quality is somewhat inferior to fruits and vegetables from an electric dehydrator. In gas ovens, the pilot light provides enough heat. If your oven is electric, make sure it has a setting as low as 140F, or that the “warm” setting doesn’t exceed 140, or you will cook your food instead of drying it. Oven drying takes longer since the temperature isn’t constant and most ovens lack air circulation to move the moist air away from the food pieces.

Make drying trays by placing clean wire cooling racks on cookie sheets or jelly roll pans and arrange the food on the trays. Keep the oven at or as close to 140F as possible, with the door slightly ajar to let air circulate and moist air escape. Do not use oven dehydrating if you have small children in the house, as they may hurt themselves on an oven that is left on and open. Rearrange the trays periodically to ensure even drying.

Sun or Solar Dryers

Sun drying produce is the most economical way to dehydrate, since it uses the ambient heat and sunlight. However, you need an agreeable climate with several days of hot, sunny, dry weather. Excessive humidity or a cool spell hampers sun drying efforts. In all but the most arid climates, sun drying is best reserved for herbs and produce that has a very low water content to begin with. Be sure to protect sun-drying produce from insects, birds and airborne dirt.

For complete instructions on solar drying, check out Fun Family Project: Solar Food.

Preparing Foods for Dehydrating

Most fruits just need to be washed and cut into pieces, 1/8 to 1/4 inch thick, to prepare for dehydrating. Fruits that discolor quickly like peaches, pears and apples should be dipped in lemon juice or treated with ascorbic acid to prevent browning as they dehydrate. Slicing the fruit directly into a solution of 1 gallon water and 3-4 dissolved vitamin C tablets also works. Inedible parts like stems, seeds and pits should be removed. Apple peels tend to get tough during dehydrating and may cut tender gingiva. Most dehydrated vegetables should be flexible and leathery but not sticky when done.

Many vegetables, too, can simply be sliced and dried. Green beans and root vegetables benefit from being blanched first, since blanching starts breaking down the cell walls to release the moisture, shortening drying time. Blanching also destroys some of the enzymes that will otherwise cause the dehydrated vegetables to quickly lose flavor and quality. Most dried vegetables should be brittle when sufficiently dried. Dried tomatoes should be leathery.

Once the fruits or vegetables are washed and treated, if pretreatment is necessary, arrange the pieces in a single layer on the dehydrator trays. Ideally, pieces should not touch, but with some vegetables like shredded carrots or cabbage, this may not be possible. Produce shrinks as it dries, so you can spread the pieces out as the drying progresses.

Using Dehydrated Foods

Dehydrated fruits, and even many dehydrated vegetables, can be eaten as-is. Dried fruits make a great sweet snack. Dried seasoned zucchini slices can satisfy a savory snack craving.

Dehydrated fruit can also be reconstituted and used as you would fresh in cooked recipes, including compotes and pie fillings. Add a handful of dried fruit bits when boiling the water to make hot cereal to pep up your oatmeal or 7-grain cereal and work another serving of fruit in with no extra work. The texture difference makes reconstituted dried fruit an unlikely substitute for fresh fruit in uncooked recipes.

While some people reconstitute dried vegetables to use as a side dish, the texture and flavor is slightly different from fresh, canned or frozen vegetables. Simply cover with water and simmer until the vegetables are tender.  To make soups, stews or casseroles with dehydrated vegetables, simply add the dried vegetables straight in with the broth or other liquid ingredients.  Add about 1 cup extra liquid for each cup of dehydrated vegetables.

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Posted under Cooking Healthy, Food, Nutrition & Recipes.