Regardless of how brilliant the design, or how skilled the fabricators might be, it is the operators of a Tray Dryer that will make it a success, or failure.

Drying is the oldest known method of preserving food. Historically, food was dried in the sun. Nowadays, we can sun dry or dry in an oven or a dehydrator that is especially designed for home drying.

Drying has many advantages. It is safe. By removing most of the moisture from a food, microorganisms can't grow in it. Dried food is compact so that less storage space is needed. Plus, dried foods keep well, travel well and add variety to our diets.

Reconstituting — restoring moisture to a dried food. Properly dried foods return to approximately their original size, form and appearance.

Sulfite Solution — solution of 1 water and sodium sulfite, sodium bisulfite or sodium metabisulfite. Soaking fruit 10 minutes in this solution effectively prevents changes in color, flavor and nutrition. Sulfite-sensitive people should choose another pretreatment.

Sulfuring Fruit — pretreating fruits with the fumes of burning sulfur. This method is done outdoors in a partially ventilated container and effectively maintains food quality. Sulfite- sensitive people should choose another pretreatment.

Fruits and vegetables selected for drying should be of the highest quality -- fresh and ripe. Drying does not improve the quality. Immature produce will lack flavor and color. Overmature produce may be fibrous or mushy. If the food is not perfect for eating, it is not suitable for drying.

Dried Vegetables can be used as chips, reconstituted for a cooked side dish, used in soups, stews, casseroles and stuffings or made into powders. (To powder: use very dry vegetables and put only one-half cup at a time in a blender.) Dried Fruits tend to be chewy and make delicious snacks. Pieces of dried fruits are good in cookies, muffins, cakes and breads. They can also be reconstituted and used in sauces, pies or cobblers or added to gelatin salads, cooked cereals and ice cream.

Fresh fruit and vegetables provide us with bulk, energy, minerals and vitamins. Bulk is provided by the indigestible fiber and energy is provided by the carbohydrates and protein. Neither bulk nor energy is lost in the drying process. During blanching, a small portion of the vitamin C may be lost by leaching. The amount varies depending on the care taken in blanching. To keep leaching to a minimum, blanch only as long as required. Do not under- blanch, however, because then the food's enzymes will still be active, reducing the quality. Pretreating light-colored fruits helps protect against loss of vitamins A and C.

To avoid nutrient losses during drying, follow these guidelines. Dry food quickly at a maximum of 150°F with good air circulation and low humidity. Eat the dried food as soon as possible. Store a maximum of 6 months to 1 year in airtight containers.

Nutrients are concentrated in dried food, compared to fresh on a per pound basis. But you need to eat an amount equal to the fresh to get the same nutrition (2 fresh apricots = 4 dried halves).

Trim away inedible and damaged portions. Cut into halves, strips or slices. Make the pieces a uniform size so they will dry more evenly. A good size is ¼-inch thick. Leaving the peel on is optional for most foods.

Arrange food on trays in a single layer. You can dry different fruits or vegetables at the same time if they have similar drying times and odors. Don't add fresh food to the dehydrator when the food already in it is nearly dry because the drier food may reabsorb moisture.

Blanching is essential for all vegetables except onions, peppers, okra, herbs, and some new types of corn that get sweeter as they mature.

Blanching helps save some of the vitamin content, sets the color, hastens drying by relaxing the tissues, and helps food reconstitute.

Most fruits such as berries, cherries (pitted), seedless grapes, melons, prunes and plums require no pretreatment before drying.

Light-colored fruits, especially apples, apricots, peaches, nectarines and pears, tend to darken during drying and storage. This process, called oxidation, robs the fruit of flavor, color and vitamins A and C. To prevent this, you must pretreat the fruit in one of the following ways.

The most effective pretreatment is "sulfuring." Prepared fruit is exposed to fumes of burning sulfur. This must be done outdoors.

Indoor pretreatments include dipping the cut fruit in sulfiting solutions, ascorbic acid solution, or syrup blanching. These methods are not as effective as sulfuring, but may be used by people who are sulfite-sensitive.

Sulfur dioxide and sulfiting agents, like sodium sulfite, sodium bisulfite and sodium metabisulfite, are hazardous to the health of a small group of people. It is estimated that 5% of asthmatics are sensitive to sulfites, and an unknown number of nonasthmatics. The symptoms are sudden attacks of asthma, difficult breathing, nausea, diarrhea and even death. Persons who are sulfite-sensitive should not use any sulfur-containing products to pretreat fruit before drying, and should not eat food treated with sulfur.

You can satisfactorily dry produce wherever you have a fairly constant temperature (as close to 140°F as possible), low relative humidity and circulating air.

Products dried in controlled heat generally are superior to sun-dried ones in color, flavor, cooking quality and nutritive value. Oven or dehydrator dried foods will also be free of insects. However, controlled heat drying requires additional equipment and operating expenses.

Consider the following factors in choosing the method best for you.

Solar Drying is like sun drying only better. You are still dependent on the weather but the sun's rays are concentrated so drying time is shortened. The back window of a car with the windows open slightly to allow air flow is an example. You may wish to build a solar oven.

Sun Drying depends on the weather, the temperature and relative humidity outside. If you live in a hot, dry climate, sun drying may be successful. Its advantage is the cost. The only investments are drying trays, netting to protect against insects and the food itself. Its main disadvantage is time. What would take 6 to 10 hours to dry using another method may take 3 to 5 days in the sun. To avoid scorching, move the food into the shade to finish when it is about two-thirds dry.

Oven Drying is small-scale drying. It's a good choice if you want to dry only 4 to 6 pounds of produce at a time. Disadvantages are the cost of the energy and having the oven on constantly. Oven drying takes 2 or 3 times longer than a dehydrator. You must rotate and shift trays every half hour and turn the food occasionally to assure even drying. To avoid scorching food, turn off the heat when drying is almost completed and open the oven door wide.

Dehydrator Drying is a more reliable method. Dehydrators should have a heat source, thermostat and some method of air circulation. They can be purchased or made. When selecting a dehydrator consider:

Capacity — drying area in square feet (each square foot holds about 1 pound produce); adequate size for family needs; easy to handle and move.

Construction — sturdy, safe and durable (metal and high-grade plastic are superior to wood for safety, durability and cleaning; wood eventually dries, absorbs odors and warps); double-wall construction to cut heat loss; convenient to load and unload; adequate venting; easy to clean; trays slide in and out easily; trays are food-safe plastic, stainless or nylon; trays have durable mesh and are replaceable.

Operating parts — constant heat source; heating element enclosed; parts easy to replace; wattage adequate and suitable for average circuit; temperature dial easy to read; dial easy to adjust; fan for even air distribution that is quiet and durable.

Economy — cost per square foot of drying area; a model with lowest cost per square foot may not be economical if it doesn't hold enough; electricity use.

Safety — nonflammable construction; enclosed, properly wired electrical components; nontoxic finishes; warranty; repair location; no sharp edges or corners; instructions for use and maintenance.

Other appliances, such as some forced convection ovens (with drying trays as optional accessories), may be used for food drying. Foods can be dried in a convection microwave; it's the convection cycle, not the microwaves, that actually dry the food. Read the directions that come with those ovens for more information.

Fruits, vegetables and meats should not be dried in a microwave for two reasons: 1. The oven door must be open for moisture to escape. A microwave can only be operated with the door shut; and 2. Drying times vary. Foods can become so dry they ignite and burn out the magnetron tube.

You can make your own drying trays. They should be made of a food-safe material that allows good air circulation

Use:
• Stainless steel screening
• Aluminum screens
• Food-grade plastic mesh
• Cheesecloth or nylon netting
• Wood slats (wood free of pitch and odors)

Avoid:
• Galvanized screening
• Zinc and cadmium-coated screens
• Copper screening
• Fiberglass (unless teflon coated)
• Cheesecloth used in a gas oven
• Screens may sag; construct the trays to allow restretching netting or screening periodically. If the food sticks, spray the tray with a no-stick vegetable spray.

Remove a few pieces to test and let them cool. Fruit should be pliable and leathery. Squeeze a few in your hand and see if they spring apart. Tear one open and see if it is dry inside. Vegetables should be hard and brittle. They should shatter when hit with a hammer. Remove enough moisture to prevent mold growth during storage, but do not over-dry. If you prefer to dry your foods moister than recommended, freeze the dried food for safer storage.

These leathery sheets of dried fruit or vegetable puree are easy to make at home. They are a good way to use overripe fresh produce or leftover frozen and canned foods..

Equipment:

• Blender or food mill
• Plastic wrap
• Cookie sheets
• Oven, dehydrator or sun
• Large saucepan (optional) to concentrate the puree

Ingredients:

Combine any foods that sound appetizing. Apples combine well with all fruits. Tomato leather adds a concentrated flavor to spaghetti sauces. Other vegetable leathers make good soup bases.

Preparation:

Select the food (overripe fruit or vegetables, frozen or canned fruits, vegetables, applesauce, etc.)

Wash and cut away blemishes. Remove pits from fruit. In most cases seeds and peel need not be removed.

Cut food into chunks. Heat in saucepan with a little water if needed to soften it up and make a smoother texture.

Add food to blender gradually until it is a smooth puree. Watery puree can be concentrated by cooking over low heat until the mixture thickens.

Flavoring the puree is up to you. To sweeten add sugar or honey to taste. Spices like cinnamon, nutmeg and mint are good with fruits, while onion powder, marjoram or basil are good with vegetables. Add one flavoring at a time in small amounts and taste. When the puree is dried, the spices and flavoring will concentrate so use them sparingly. If the puree is too strong add more fruit or vegetable. Add 1 tablespoon lemon juice per 2 cups puree to help preserve natural color in light-colored fruits.

When you have a tasty puree, pour it out onto a cookie sheet lined with plastic wrap. (Tape the wrap to the edges.)

Spread the puree around so that it is about 1/4-inch thick. If desired, you can garnish it with coconut, nuts, sesame or sunflower seeds sprinkled lightly on top.

Dry by using one of the drying methods discussed previously. Generally, it will dry in 4-10 hours in the oven or dehydrator and from 1 to 3 days in the sun.

Properly dried leather will be slightly sticky to the touch but will peel readily from the plastic.

Loosely roll up the leather and then wrap it in plastic wrap or put in an airtight bag or container. For best quality, use within 3-months when stored at room temperature, 6-months in the refrigerator or within a year if frozen.

Use leathers in lunches, for camping, or when traveling. Spread with peanut butter, cream cheese, cheese spread or melted chocolate. Roll two (2) fruit leathers together. Make into a beverage by combining five (5) parts water with one (1) part leather in a blender. Crumble vegetable leathers into soups for concentrated flavor.

By growing and drying your own herbs, you will always have a fresh inexpensive supply close. For people on salt-free diets, herbs enhance the flavor of otherwise bland foods.

Harvest young tender leaves. They are more flavorful and aromatic than older leaves. Rinse gently in cool water and drain well on paper towels.

Hang dry herbs with long stems (savory, rosemary, sage, mint and marjoram). Tie stems together in small bunches. Hang upside down in a warm, dry, airy place, but not in the sun. Allow 5 to 10 days to dry. Store dry leaves in airtight containers.

Dry seeds and herbs with short stems on trays. Spread seeds or leaves in a single layer on a cookie sheet. Dry in a warm, airy place 4 to 6 days or dry in 140°F oven 1-4 hours.

Herbs can also be dried in a microwave because the leaves contain little moisture and dry rapidly. Place a single layer of herb leaves between paper towels. Dry them for 1 to 2 minutes in the microwave, depending on the thickness of the leaves. Cool and test for brittleness. When the herb leaves crumble in your hands, they are done. If leaves are not dry, microwave ½- to 1-minute longer.

Do not sun dry herbs. Sunlight destroys their natural aroma. Whole herbs keep their flavor longer than crushed or ground herbs.

Use 1/3 as much dried herbs as you would fresh. Store in dark, cool, dry place in airtight containers for up to 1 year, or freeze.

Select sunflowers with dry stalks. Remove seeds. If plants were sprayed, wash the seeds and pat dry. Spread on cheesecloth or screening. Dry in a warm place for at least a week. An alternate method is to hang the flowers in a cool, dry place for a month or until the seeds pop out. Tie a cloth or mesh bag around the flower to catch seeds that fall. The seeds must be thoroughly dry.

To toast the seeds, measure 4 cups seeds and ½ cup salt into saucepan. Add water to cover. Bring to a boil; boil 5 minutes. Drain; spread on absorbent paper to dry. Place in shallow baking pan; bake at 325°F for 25-30 minutes, stirring occasionally. Cool thoroughly. Store in a dry place in an airtight container like a plastic bag or glass jar. One flower makes about 3 cups of seeds.

Bananas — Cut in ¼-inch thick slices. Dip into orange juice, pineapple juice or lemon juice. Dry until leathery or until crisp, whichever you prefer.

Melon — All varieties can be dried and will taste much sweeter when dried. Remove rind and seeds. Cut into ¼-inch thick slices about 2-inches long. Dry 6-16 hours in a dehydrator until pliable. The pieces may be slightly sticky.

Celery — Wash and cut stalks into 1/2-inch pieces. Steam 2 minutes. Dry until brittle. Best used in soups.

Mushrooms — Clean and slice. Arrange in thin layer on trays. Dry until leathery.

Horseradish — Wash and peel or scrape roots. Grate or cut into 1/8-inch slices. Dry until very brittle and powdery.