Drying Vegetables -- Purdue University Extension Service
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DRYING FOODS at Home
Mary K. Wagner, Mary E. Mennes and Clarence E. Johnson
Food dehydration is a method of preserving food that fits today's lifestyles. Drying food offers one of the most economical and energy efficient ways of preserving a variety of foods. It is estimated that drying costs less than canning and one-quarter the cost of freezing.
Drying not only preserves foods but also offers new and different nutritious snacks such as dried fruits, fruit rolls and meat jerkies.
How Drying Works as a Preservative
The purpose of drying is to preserve food by lowering the amount of water or moisture in the food material to a point where microbial growth (bacteria, yeast and mold) and chemical reactions (enzymatic deterioration) cannot destroy the food during storage. Though drying itself does not destroy enzymes, the dried food (especially pretreated dried food) is considered to be low enough in moisture to prevent enzymatic deterioration. Because drying removes moisture, the food shrinks and decreases in size, becoming lighter in weight and easier to store.
When food is ready to use, the water is added back and the food returns to its original shape and form. The heat used in drying is generally at a low temperature (120 to 150 F). If higher temperatures are used, the food cooks rather than dries. When the temperature is too high, the food cooks on the outside and the moisture cannot escape, causing "case hardening" and molding of the food.
The drying process should never be hurried by raising the temperature during drying. Low humidity aids the drying process, especially if the food naturally contains a lot of water. To dry food, the water must move from the food to the surrounding air. If the surrounding air is humid, drying of the food will be slowed down. Air currents speed up drying by moving the surrounding moist air away from the food surface and drawing fresh dry air into contact with the food.
Foods can be dried by two general procedures: indoor or outdoor drying. Foods dried by indoor drying can be dried in an oven, food dehydrator or by the air. In outdoor drying, the food is dried directly in the sun, by a solar drier or on the vine. Outdoor drying is not recommended in Wisconsin because complete drying cannot be assured and the end quality of the food is questionable.
All drying methods requite the same essential guidelines of warm temperatures, low humidity and an available air current.
General Drying Procedures
When selecting foods for dehydration, choose only foods that are in prime condition and perfectly fresh, just as you would for any other method of preservation. Although drying foods prevents microbial growth, certain chemical reactions caused by enzymes can still occur unless the product is pretreated before drying. Fresh produce, for example, contains many different enzymes which cause loss of color and nutrients and flavor changes in dried vegetables and fruits. These particular enzymes must be inactivated by pretreating the food to prevent such reactions from taking place during the drying of the food.
Enzymes in vegetables are inactivated by the blanching process, which exposes vegetables to boiling water or steam for a brief period of time. Blanched vegetables, when dried, will have better color and flavor than unblanched.
The major problem associated with enzymes in fruits is the development of brown colors and the loss of Vitamins A and C. Fruits are not blanched like vegetables because the blanching process gives them a cooked flavor. Instead, the enzymes in fruits are inactivated by using chemical compounds which interfere with deteriorative chemical reactions. The most common control chemical used is ascorbic acid (Vitamin C). Ascorbic acid may be used in its pure form or in mixtures of ascorbic acid with citric acid and/or sugar. Sodium bisulfite is no longer recommended as a pretreatment chemical due to the increased number of people reporting sensitivities to sulfiting agents.
Indoor Drying Methods
Food Dehydrators. A food dehydrator is a small electrical appliance for drying foods indoors. Most food dehydrators have an electric element for heat and a fan and vents for air circulation. Efficient dehydrators are designed to dry foods rapidly and uniformly. They vary in cost from $50 to $300, depending on features. Some models are expandable so that additional trays can later be purchased. In general, 12 square feet dries a half-bushel of produce.
There are two basic designs for dehydrators: One has horizontal air flow and the other vertical air flow. The major advantages of horizontal flow are that it reduces flavor mixture, several different foods can be dried at one time, all trays receive equal heat penetration and juices or liquids do not drip down into the heating element. The heating element and fan are on the side.
Vertical air flow has the heating element and fan located at the base. If different foods are dried, flavors can mix and liquids can drip into the base.
Dehydration of various fruits and vegetables at the University of Wisconsin-Madison, using the two types of dehydrators, has shown a difference in the final product depending on the type of dryer used. The vertical dryer usually dried food faster but readily over-dried the food if dried according to standard recipe specifications.
Helpful Hints for Using a Food Dehydrator:
* Spray trays with a non-stick pan coating spray to avoid sticking.
* Place food in a single layer. Avoid overlapping.
* Cut food in uniform sizes, shapes and thickness.
* If the heat source and fan are at the bottom, the aromas will mix, so dry similar flavored foods. Horizontal fans and heat do not mix aromas.
* It is best not to dry strong-smelling foods such as onions and garlic in the home. The odors may linger in drapes, clothes and furniture. Place the dehydrator in a carport or covered porch or patio. Protect the dehydrator from the rain.
* Near the end of the drying period, observe the food closely to avoid scorching.
The suggested temperatures for dehydrators with temperature control are:
Vegetables 125 F
Fruits, Fruit leathers 135 F
Jerkies 145 F
Portable dehydrators can be used on a 110/120 volt general purpose circuit
(15 AMP). When drying a particular food, follow the recipe accompanying the
commercial dehydrator closely for a successfully dehydrated product. For
additional information on food dehydrators, see University of
Wisconsin-Extension publication B3251, Selecting a Food Dehydrator.
Oven Drying. Everyone who owns an oven owns a food dehydrator. By combining
the three factors discussed earlier: heat, low humidity and air current, an
oven can be used as a dehydrator
An oven is ideal for occasional drying of meat jerkies, fruit leathers and
banana chips or for preserving leftovers like celery or mushrooms. Because
the oven is needed for cooking, it may not be satisfactory for preserving
abundant garden produce.
Drying in an oven is slower than in a dehydrator because ovens do not have
built-in fans for the air movement (however, some convection ovens have a
fan). It takes two to three times longer to dry food in an oven than in a
dehydrator Thus, the oven is not as efficient as a dehydrator and uses a
great deal more energy.
To use your oven, check the oven dial to see if it has a reading as low as
140 F If the thermostat does not go this low, your food will cook instead
For air circulation, leave the oven door propped open 2 to 4 inches. Place
a fan near the outside of the oven door to improve circulation.
Because the door is left open, the drying temperature will vary. An oven
thermometer placed near the food gives an accurate reading of the drying
temperature. Adjust the temperature dial to give proper heat. Ovens can be
heated 20 degrees higher than the recommended drying temperature and
lowered to the suggested temperature after 2 hours.
Place food on wire racks 2 to 3 inches apart for proper air circulation.
Air Drying. This drying method differs from sun drying, since it takes
place indoors in a well-ventilated attic, room or screened-in porch. Herbs,
hot peppers and mushrooms are the most common air-dried items.
Herbs and peppers are not pre-treated, but are simply strung on a string or
tied in bundles and suspended from overhead racks until dry. Enclose them
in paper bags to protect them from dust, loose insulation or other
Microwave Drying. Drying food successfully in a microwave oven is not
possible, except for herbs and some leaf vegetables. Food which has been
microwave dried tastes overcooked rather than dried. To dry herbs and leaf
vegetables in a microwave, follow instructions in a microwave cookbook, or
on page 15.
Dehydrofreezing. Dehydrofreezing is a new method of food preservation that
combines the techniques of drying and freezing. Fruits or vegetables dried
at home have had 85 to 90 percent of their moisture removed to prevent mold
growth. However, by removing only 70 percent of the moisture and storing
the fruit or vegetable in the freezer, a tastier product results. The
freezer's low temperature inhibits microbial growth.
Fruits and vegetables processed this way have good flavor and color and
reconstitute in about half the time it takes for dried foods.
This process is not freeze drying, which is a costly commercial technique
that forms a vacuum while the food is freezing and is not available for
Outdoor Drying Methods
Sun Drying. The high sugar and acid content of fruits make them relatively
safe to dry outdoors. Sun-dried raisins are the best known of all dried
foods. The San Joaquin Valley in California produces the world's largest
supply of raisins. The warm temperature, low humidity and constant breeze
in the valley are ideal conditions for drying grapes.
High humidity or low drying temperatures are conditions that could halt the
drying process, thus allowing favorable surroundings for the food to mold
or rot before it is dried. For these reasons, outdoor drying of foods is
not recommended in the Midwest.
All foods dried outdoors also need a pasteurization treatment following
drying to kill insects and their eggs. Unless destroyed, the insects will
eat the dried food.
There are two recommended pasteurization methods:
Freezer Method. Seal the food in a plastic freezer bag, place in a freezer
set at 0 F or below and hold for at least 2 days (48 hours).
Oven Method. Place the food on a tray or in a shallow pan and put in an
oven preheated to 140 to 160 F for 30 minutes. Spread the food in a single
layer when pasteurizing and package it as soon as possible following the
brief heat treatment.
Solar Drying. Efforts to improve on sun drying have, in recent years, led
to what is known as solar drying. Solar drying still uses the sun as the
heat source, but a specially designed container increases the temperature
and air current to speed up drying. The shorter drying time reduces the
risk of food spoilage or molding.
Solar driers use a reflectant such as aluminum foil or glass to increase
the sun's temperature from 85-100 F to 105-130 F. Air movement is increased
by using air vents at each end. Cooler air enters the dryer, crosses the
food, removes moisture and escapes. Plastic covers the frame and prevents
rain or condensation from dampening the food. Screens over the vents keep
insects and birds off the food.
Solar dryers may need turning or tilting throughout the day to capture the
direct, full sunlight. Food on the shelves needs to be stirred several
times a day. Again, the food must be pasteurized prior to storage.
Vine Drying. Another method of drying outdoors is drying on the vines. To
dry beans (navy, kidney, butter, great northern, lima, lentils and
soybeans), leave bean pods on the vine in the garden until the beans inside
rattle. When the vines and pods are dry and shriveled, pick the beans and
shell them. No retreatment is necessary. If beans are still moist, the
drying process is not complete and the beans will mold if not more
thoroughly dried. If needed, drying can be completed in an oven or a
dehydrator Pasteurization is needed for those beans dried entirely in the
Determining Dryness of Food
Drying food is a slow process. Solar drying takes 1 to 2 days. It will take
6 or more hours to dry foods in a dehydrator and 8 or more hours in your
oven. Drying time depends on type of food, thickness and type of dryer.
Don't be tempted to speed up the drying time by increasing the temperature.
You will end up cooking the food on the outside before it dries on the
inside. This is called "case hardening" While the food may appear dry on
the outside, it can be moist on the inside. Moisture left in the food will
cause the food to mold.
To determine the dryness of the food, look, feel and taste it. Remove
several pieces of food from the dehydrator When the food has cooled, cut
through the center of the thickest part. There should be no visible signs
of moisture. A darker, wet interior indicates the need for extended
To test for doneness, remove a piece of food during the end of the drying
period. Cool to room temperature and check for the following signs:
* Fruit is pliable, springy and will not stick together if
(figs and cherries may be sticky).
* Vegetables are brittle and would shatter if hit with a hammer
* Meats are very dry. Jerky is dark, fibrous and forms sharp
* Herbs are brittle.
* Fruit leathers are dry to the touch. Fruit peels away from
Packaging and Storing
Dried foods must be properly stored to maintain a low moisture content and
to prevent microbial deterioration. Before packing the foods, allow the
dried pieces to cool. Immediately after the product has cooled, the food
should be equilibrate for 5 to 10 days before storing. Place food in a
covered container and recheck each day to see if the product is
sufficiently dry; if not, dehydrate longer
To store dried foods, pack them in clean, dry, insect-proof containers as
tightly as possible without crushing. A recommended dry storage method is
to place the dried food in plastic bags, press out air, seal or close and
place in tightly sealed glass jars. Old peanut butter, mayonnaise or other
one-trip jars are recommended for storage of dried food.
To be sure that the food remains dry, add dessicant or silica gel, which
are available in the notions or housewares section of department stores or
at hobby shops. Place the substance in the glass jar to cover the bottom of
the container to a depth of 114 inch. The dessicant absorbs any moisture
from the surroundings and prevents the food from absorbing moisture. Place
the dried food wrapped in a closed plastic bag over the dessicant and
tightly seal the jar
Packaged dried food should be stored in a dry; cool place at about 60 F
Because food quality is affected by heat, the storage temperature helps
determine the length of storage; the higher the temperature, the shorter
the storage time. An acceptable storage area in winter may be too warm in
the summer. Keep dried food out of the sun to prevent discoloration and
nutrient loss. Some dried foods can also be stored successfully in the
refrigerator or freezer.
Foods that are packaged seemingly "bone dry" can spoil if moisture is
reabsorbed during storage. Check dried foods frequently during storage to
see if they are still dry. Foods affected by moisture but not spoiled
should be used immediately or redried and repackaged. Moldy foods should be
Rehydration of Dried Foods
Water removed during drying must be replaced either by soaking, cooking or
a combination of both.
Dried vegetables need about 2 hours soaking time before cooking. When you
soak or rehydrate the vegetables, they should plump to nearly the same size
they were when fresh. Start with 1-1/2 to 2 cups water for each cup of
dried vegetables. If necessary, add more water during the soaking process.
Soak root, stem and seed vegetables for 1/2 to 2 hours in sufficient cold
water to keep them covered (soaking in too much water may cause
over-softening of vegetables). After soaking, simmer until tender, allowing
excess water to evaporate. Greens, cabbages and tomatoes do not need to be
soaked. Simply add sufficient water to keep them covered and simmer until
tender. Many vegetables lose their fresh flavor during drying. For this
reason, flavorings such as basil, garlic, onions and chili sauce may be
added during cooking to improve flavor Cook the vegetables in the same
water in which they have soaked to save nutrients. Dehydrated vegetables
are usually not used as cooked side dishes. They are best when used as
ingredients for soups, casseroles, sauces, stuffings and stews.
Dried fruits can be eaten or used in recipes as they are. If you wish to
plump or soften the fruit slightly to make it more chewable, you can use
one of these methods:
* Cover the dried fruit with boiling water, let it stand for 5 minutes and
* Place the dried fruit in the top of a steamer over boiling water and
steam 3 to 5 minutes until the fruit is plump.
Foods You Should Not Dry at Home
Milk, eggs, fish and poultry are not recommended for home drying.
Salmonella and Staphylococcus bacteria, which thrive on these foods, can
survive and grow at low temperatures used to dry meat and dairy products.
These bacteria grow very rapidly in such products because all the nutrient
needs of these pathogenic or disease-producing bacteria are supplied by
poultry, eggs and dairy products.
Salmonella and Staphylococcus have caused food poisoning outbreaks in
Nutritive Value of Dried Foods
The nutritive value of dried foods, like that of foods preserved by canning
and freezing, depends largely on the care exercised in preparation,
processing and storage. Some of the sugars, salts and water-soluble
vitamins are lost during preparation. Some of the volatile oils and esters
and readily oxidizable substances such as ascorbic acid (Vitamin C) are
lost during the drying process. The Vitamin A content of vegetables
decreases during storage. The loss of this vitamin is greatest in
unblanched vegetables. Carbohydrates, minerals and proteins are
concentrated but are otherwise unaffected by drying. Further loss of
nutrients can occur during storage unless the foods are properly packaged
To keep the nutritional losses to a minimum, package dried foods in
air-tight containers, store them at the lowest temperature possible and
consume them within several months to a year after processing.
For diabetics or dieters, dried fruits may satisfy a craving for sweets,
but be careful to consume only the amount equal to the fresh fruit
exchange. Drying removes water, not calories.
Dried fruits are unique, tasty and nutritious. It might be argued that they
are even tastier than fresh fruits and have been called nature's candy.
They taste sweeter because the water has been removed, thus concentrating
the fruit's flavor. Dried fruit can be eaten as a snack or added to
cereals, muffins or ice cream.
Preparing the Fruit
There are many ways to slice fruit for drying. Thin, even, peeled pieces
dry the fastest. The peel can be left on the fruit, but it will take longer
to dry. Use a food processor for uniform, even slices.
Because fruits contain sugar and are sticky, spray the trays with nonstick
pan coating spray before placing fruit on them. After the fruit dries for 1
to 2 hours, lift each piece gently with a metal spatula and turn.
Fruits dried whole take the longest to dry. Skins need to be cracked to
speed up drying.
Pretreating the Fruit
Many fruits will darken rapidly after peeling due to oxidation, but there
are several ways to prevent this color change:
Ascorbic acid (Vitamin C) is effective in preventing oxidation of most
fruits. Ascorbic acid, in crystalline or tablet form, is available at
drugstores. One teaspoon weighs about 3 grams (3,000 milligrams). Use 1/2
teaspoon per quart of water as a dip to hold sliced peaches, apples, pears
or similar fruits while you get them ready for drying. Ascorbic acid may be
added directly to fruit purees.
Ascorbic-citric acid mixture (A-C-M Everfresh*). Available in many
supermarkets; can be used to prevent darkening. Use according to
Ascorbic acid-sucrose mixture (Fruit-Fresh*). This product, available in
supermarkets, is another anti-darkening product which should be used
according to manufacturer's directions. Because the ascorbic acid is
diluted by the presence of sugar in the mixture, larger amounts than pure
ascorbic acid are needed.
Lemon juice or citric acid can help prevent darkening of some fruits, but
are not as effective as ascorbic acid. One tablespoon lemon juice per quart
of water can be used as a dip. There may be a slight but usually
unobjectionable flavor change.
Simply dipping the fruits into a fruit juice containing Vitamin C (ascorbic
acid) will help keep the natural color and prevent further darkening. Other
suggested fruit juices include orange, lemon, pineapple (may be diluted
half strength with water), grape or cranberry with added Vitamin C.
Pour 2 cups fruit juice into a 1 to 2-quart bowl. Slice fruit and place
immediately in the bowl of juice. Soak fruit for 3 to 5 minutes, drain and
place on sprayed trays. Fruit juice can be reused; cover and store in
refrigerator and use within 1 to 2 days.
Honey is a sweetened dip that coats fruit to prevent darkening. Many of the
commercially produced dried fruits are honey-dipped. This method can be
used at home. Honey-dipped fruits are higher in calories.
Prepare the dip by dissolving 1/2 cup sugar in 1-1/2 cups boiling water.
Cool to lukewarm and add 1/2 cup honey. Makes 2-1/2 cups. Dip fruit in
small batches. Allow to soak 3 to 5 minutes. Remove with slotted spoon and
This is another type of sweetened dip. Combine 1 cup each of corn syrup,
sugar and water. Bring to boil, add fruit, simmer 15 to 20 minutes and
drain well. Place on sprayed trays and lift fruit gently. Syrup dip
increases drying time. This product is like a candied fruit. For further
recommendations on specific fruit pretreatment, see Table 1.
Fruits are generally dried at 140 F for varying lengths of time (Table 1).
Preheat the oven or dehydrator to 160 F load trays. After 2 hours, decrease
the temperature to 140 F Drying times vary. Fruits are soft and pliable and
not tacky when dry. Banana and apple chips can be dried until they are
crisp. For recommended drying times, see Table 1 (remember to follow drying
times specified for your commercial dehydrator, if available).
Vegetables contain less carbohydrates and dry faster than fruits. Drying is
an excellent way to preserve potatoes, onions and green or red peppers.
Unused celery or mushrooms can be preserved for later use by drying.
For vegetables, drying time is crucial to tenderness. The longer the drying
time, the less flavorful and the poorer the product. Drying time can be
hastened by drying small uniformly cut pieces. To achieve this, a food
slicer or food processor can be used.
Vegetables also have a lower moisture content than fruits; therefore, a
lower dryer temperature of 125 F is needed (tomatoes and onions with more
water can be dried at 140 F).
Vegetables dry much faster than fruits. Also, as the drying period ends,
they give up moisture rapidly. Vegetables will scorch if too high a
temperature is used and if dried too long. They will be brittle when dried.
Wash vegetables in cool water to remove soil. Trim, peel, cut, slice or
shred. Remove any fibrous or woody portions and core when necessary,
removing all decayed and bruised areas. Keep pieces uniform in size so they
will dry at the same rate and prepare only as many as can be dried at one
time. Holding vegetables, even in the refrigerator, after washing and
preparation for drying will result in loss of quality and nutrients. Dry
vegetables immediately after harvesting.
Blanching is a necessary step in preparing vegetables for drying. It stops
the enzyme action which causes loss of color and flavor during drying and
storage. It also sets the color and shortens the drying and rehydration
time by relaxing the tissue walls so moisture can escape or enter more
rapidly. By definition, blanching is the process of heating vegetables to a
temperature high enough to destroy enzymes present in the tissue. In water
blanching, vegetables are submerged in boiling water. In steam blanching,
they are suspended above the boiling water and heated only by steam. Water
blanching usually results in a greater loss of nutrients but takes less
time than steam blanching. Recommended blanching and drying times are shown
in Table 2.
Water Blanching. Fill a large kettle 2/3 full of water, cover and bring to
a rolling boil. Place vegetables in a wire basket or colander and submerge
them in the water. Cover and blanch according to directions for each
vegetable (Table 2). If it takes longer than 1 minute for the water to come
back to a boil, too many vegetables were added. Reduce the amount in the
To stop blanching, see "Cooling Process" below.
Steam Blanching. Use a deep kettle with a close-fitting lid and wire
basket, colander or sieve placed so steam will circulate freely around the
vegetables. Place vegetables loosely in the basket no more than 2-1/2
inches deep. Add several inches of water to the kettle and bring to a
rolling boil. Place the basket of vegetables in the kettle. Make sure the
water does not come in contact with the vegetables. Cover and steam
according to directions for each vegetable (Table 2).
Cooling Process. After blanching, dip the vegetables briefly in cold water,
only long enough to stop the cooking action; do not cool them to room
temperature. When they feel only slightly hot to the touch, they will be
cooled to about 120 F Drain the vegetables by pouring them directly onto
the drying tray and arrange them in a single layer Then immediately place
the tray in the preheated dehydrator The heat left in the vegetables from
blanching will cause the drying process to begin more quickly.
Dried Food Specialties
Fruit leather is made by drying thin layers of pureed fruit or leftover
fruit pulp in the oven, sun or dehydrator. While most fruits or fruit
combinations can be used for making fruit leathers, grapefruit and lemons
are not recommended because they turn bitter when dried.
Some references for preparation of fruit leather suggest heating the fruit
before drying to stop enzymatic action, help preserve the fruit's natural
color and speed the drying process. Other references simply recommend
blending the fresh fruit with an antioxident and drying the puree as is.
Both methods are given below.
Uncooked method. Select ripe or slightly over-ripe fruit. Sort and wash,
removing blemishes or defective parts of acceptable fruit. Peel apples,
oranges, peaches, pears and tomatoes, if desired. Pit and core fruit as
needed. Remove seeds from grapes, if desired. Hull strawberries. Cut fruit
into chunks and place in food chopper or blender
Add 1/2 to 1 tablespoon lemon juice or 1/4 teaspoon pure ascorbic acid
(ascorbic acid mixtures also may be used according to label instructions)
to each 2 cups of light-colored fruit to help preserve natural color and
slow enzymatic action.
Chop, grind or blend fruit until a thick puree is formed. One to 2
tablespoons water may be added to help blend some fruits. You may also wish
to add 1 tablespoon of sugar, corn syrup or honey to each 2 cups of tart
fruit such as pineapples or oranges. Additional sugar is not needed for
non-tart fruit. A small amount of spice (1/4 teaspoon or dash of nutmeg) or
1/4 cup sesame, pumpkin or sunflower seeds may also be added per 2 cups
puree, if desired.
Cooked Method. Select, wash, peel, pit and core fruit as described for
uncooked method above. Cut into slices or chunks and place in double
boiler. Add water to bottom of double boiler. Cover and cook for 15 minutes
or until soft. Crush fruit in a blender or food grinder. Addition of sugar
and spices are optional, as described above.
Shortcut Canned Method. Substitute canned fruit or baby food fruit (without
tapioca) for the cooked fruit above. Canned applesauce and strained baby
food will not need to be pureed. Other canned fruits will need to be
drained and pureed. Since canned fruits have been heat processed to stop
enzymatic action, the addition of ascorbic acid is unnecessary.
Spray a cookie sheet or similar flat tray with vegetable spray or line with
plastic wrap. Do not use waxed paper or aluminum foil, as you may end up
eating them with your fruit leather. Spread the fruit concentrate evenly
over the surface of the pan to a depth of no more than 114 inch. Two cups
puree is enough to cover a 12 x 17-inch cookie sheet.
Oven Drying. Set oven at lowest possible setting (140-150 F). Place the
trays of puree on the racks in the oven and leave door cracked open about 2
to 6 inches, depending on oven door. Check temperature of oven periodically
with thermometer. If necessary, turn oven off for short time if temperature
is too high. The fruit concentrate should dry in 4 to 10 hours. Test
frequently for dryness (See test for dryness).
Dehydrator Drying. Place sheets or trays of fruit concentrate in
dehydrator. Set temperature control at 140 to 150 F or follow
manufacturer's directions. Test frequently for dryness. Drying time will be
4 to 10 hours.
Test for Dryness. Properly dried fruit leather will be translucent and
slightly tacky to the touch, but easily peeled from the pan or plastic
wrap. After loosening the edge of the leather from the paper or pan,
loosely roll the leather in plastic wrap or waxed paper in one piece.
Storage. Store fruit leather in a cool, dry, dark place. It will keep up to
a year or more in the freezer, several months in the refrigerator or a few
weeks at room temperature (70 F). Storage time usually reflects surrounding
conditions (temperature fluctuation in refrigerator or freezer) and may
influence shelf life one way or another.
Yogurt leather is made by drying layers of plain or fruit-flavored yogurt
in a dehydrator. Follow general drying directions for fruit leathers.
Preheat dryer to 120 F put tray of yogurt in dehydrator and raise
temperature to 125 F to compensate for initial temperature drop. lower
temperature to 120 F approximately 1 hour after placing tray in dryer.
Check for doneness after 4 to 5 hours. Doneness test is similar to fruit
Meats need to be dried indoors at 145 F using a dehydrator or oven. Jerky
can be stored at room temperature for 1 to 2 months, but placing it in the
refrigerator or freezer extends its shelf life.
Jerky is a marinated meat, sliced thinly and dried. Marinades contain salt,
oil and an acetic liquid such as wine, vinegar or lemon juice. These
ingredients are important because they slow down microbial growth during
the long drying process. Do not omit any ingredient from the recipe.
A number of lean meats can be used to make jerky, including round steak,
flank steak, sirloin tip, rump roast or lean venison. Never use pork or
bear as is, but first cook to 170 F internal temperature to destroy
parasites that cause trichinosis. The use of raw turkey and chicken is
discouraged because drying does not destroy Salmonella (disease-causing
Remove connective tissue and gristle from fresh meat. Trim off visible fat
to prevent rancidity or off-flavors during storage. Freeze meat until firm,
but not solid.
Slice the meat into long, thin strips, 1/8 to 1/4 inch thick, 1 to 1-1/2
inches wide and 4 to 12 inches long. Most references recommend cutting with
the meat grain. Lay the strips out in a single layer on a smooth, clean
surface. Flatten strips with heel of hand or a rolling pin so they are
fairly uniform in thickness.
Season the meat strips by rubbing in no more than 1 teaspoon salt per pound
of fresh meat. Add pepper, garlic and onion powder, favorite herbs or other
seasonings to taste. Curing salts are also available and often contain
premixed spice mixtures.
Jerky may also be seasoned by marinating for several hours. A recipe for
seasoning with Liquid Smoke and two recipes for seasoning with marinades
are given below.
Smoke Seasoning (seasons 2 pounds lean meat)
2 tablespoons water
1/2 teaspoon Liquid or Powdered Smoke
Salt and pepper
Combine water and smoke flavoring.
Brush mixture on both sides of meat
strips. Place the meat strips, layer on
layer, in a large bowl. Cover with a plate
and put a weight on top. Refrigerate for
at least 2 hours or overnight.
Spicy Marinade (seasons 2 pounds lean meat)
l-1/2 teaspoons seasoned salt
1-1/2 teaspoons onion powder
1/4 teaspoon black pepper
1/2 teaspoon garlic powder
1/4 cup soy sauce
1/3 cup Worcestershire sauce
Combine seasonings, pour over meat
strips and mix gently. Cover and
refrigerate for at least 2 hours or oven
night. Stir occasionally while
Teriyaki Marinade (seasons 2 pounds meat)
1/4 cup soy sauce
2 cloves garlic, crushed
1 teaspoon freshly grated ginger
root or 1/2 teaspoon ground
2 teaspoons sugar
1 teaspoon salt
Combine seasonings, pour over meat
strips in a large bowl and mix gently.
Cover and refrigerate for at least 2 hours
or overnight. Stir occasionally while
Remove meat strips from marinade, if used, and pat dry with paper towels.
Dry strips in the oven or dehydrator
Oven drying. Stretch strips across clean oven racks or other drying trays.
If any strips are too short, fasten several together with wooden
toothpicks. Allow edges of the meat strips to touch but not overlap. Leave
enough open space on the racks for air to circulate around strips. Arrange
racks so that the top one is at least 4 inches below the top heat source
and the bottom rack is at least 4 inches above the bottom heat source. Set
oven temperature at 140 to 150 F and let strips dry for about 11 hours, or
until they are chewy and leathery.
Dehydrator drying. Follow manufacturers or oven drying instructions.
Test for dryness. Properly dried jerky is chewy and leathery. Be sure to
test for dryness after cooling; warm jerky will be pliable, even though
enough moisture is removed.
When jerky is sufficiently dry, remove from drying area and blot up any
drops of oil that have accumulated from marbled fat with paper towels.
Cool. Serve, or store in an airtight container. Too much air causes
off-flavors and rancidity.
Store containers of jerky in a cool, dry, dark place or the refrigerator or
freezer. Dried jerky may be stored up to a year
The best time to harvest most herbs for drying is just before the flowers
open when they are in the bursting bud stage. Rinse herbs in cool water and
shake to remove excess moisture. Discard all bruised, soiled or imperfect
leaves and stems.
Herbs with long stems such as marjoram, sage, savory, mint and rosemary can
be dried in bunches. Tie the stem ends together into small bunches and hang
them upside down in a warm, dry, shaded area. Do not hang them against a
wall. Air should circulate freely around the drying herbs to remove the
moisture without destroying the oils. If herbs are dried outside, bring
them inside at night to prevent them from reabsorbing moisture. To protect
the herbs from dust and other air-borne contaminants, place each bunch
inside a paper bag. Gather and tie the bag firmly around the stem ends so
that the herb leaves hang freely in- side the bag. Cut out the bottom of
the bag or leave air holes in the sides to provide ventilation.
Tray drying is best for seeds and large-leaved herbs such as basil and
those with short-tipped stems. Spread seeds or herbs one layer deep on
screens so air can circulate freely. If drying outside, cover trays with
cheesecloth to protect herbs from birds, insects and air-borne
contaminants. Stir or turn herbs daily to ensure uniform and thorough
Drying should be complete in 1 to 2 weeks, depending upon temperature and
humidity. When leaves are crispy dry and crumple easily in the fingers,
they are ready to be packaged and stored. Place herbs in airtight
containers and store in cool, dry, dark areas to protect color and
Microwave ovens are a quick way to dry herbs when only small quantities are
to be prepared. Place no more than four or five herb branches between two
paper towels and put in the oven. Turn oven on for 2 to 3 minutes. Remove
herbs from oven and place them on a rack for cooling. If herbs are not dry
and brittle, repeat microwave drying for 30-second intervals until dry.
Prepare and store as for air-dried herbs.
Thomas, Theodore. Dried Fruit Leathers. 1983. Cooperative Extension Service. Washington State University. Pullman, Washington,
Klippstein, R.N. and K.J.T. Humphrey. 1982. Home Drying of Foods. Extension Service. Cornell University. Ithaca, New York.
Ybarra, P.W. Preserving Food: Crying 1984. Cooperative Extension Service. University of Georgia. Athens, Georgia.
Kendall, P 1978. Leathers and Jerkies-Dried Food Specialties. Extension Service. Colorado State University. Fort Collins, Colorado.
Hertzberg, R., B. Vaughan and J. Green. 1982. Putting Food By. The Stephen Green Press. Brattleboro, Vermont.
Reynolds, S. and P.W. Ybarra. So Easy to Preserve. 1984. Cooperative Extension Service. University of Georgia. Athens, Georgia.
Table 1. Home Drying of Fruits
Treat before drying with one of these methods (minutes) Drying times --------------------------- ------------- Sun Dehy- Test for Fruit Preparation Dipping Steam Water Drying drator Dryness (cool Blanch Blanch (days) (hours) first) -------------------------------------------------------------------------------------------------------- Apples Peel and core, cut 3-5* 5, ---- 3-4 6-12 Soft, pliable, into slices or depend- no moist area rings about 118 inch thick. ing on in center texture when cut
Apricots Pit and halve for steam blanch. 3-5* 3-4 4.5 2-3 24-36** Same as for Leave whole for water blanch. apples Pit and halve after blanch.
Bananas 3-5* N.R. N.R. 4-5 5-24 Light to medium brown, pliable to brittle
Figs In dry, warm, sunny climates, it No treatment necessary 4.5 12-20 Flesh pliable, is preferable to partly dry on the slightly sticky, tree. Figs normally drop from the but not wet tree when 2/3 dry. In coastal areas, pick fruit when ripe.
Grapes: Grapes dry in less time if Optional Optional 3.5 12-20 Raisin-like tex- Muscat, blanched 1/2 to 1 minute. ture, no moist Tokay, center or any seedless grape
Nectarines For steam and water blanching, 3-5* 8 8 3-5 36-48* Same as for and Peaches leave whole, then pit and halve. apples
Pears Cut in half and core. Peeling 3-5* 6 ----- 5 24-36* Same as for preferred. (peeled apples will be soft)
Persimmons Use firm fruit when using the No treatment necessary 5-6 18-24 Light to long, softer variety, and use riper medium fruit when using the round, drier brown, tender, variety. Peel and slice with but not sticky stainless steel knife.
Prunes For sun drying, blanch in boiling Optional Optional 4-5 24-36 Leathery; pit water or steam for 1 to 1 1/2 should not slip minutes to "check" skins. For when squeezed oven drying, rinse in hot tap if prune not water. Leave whole. cut --------------------------------------------------------------------------------------------------------- *Preferred method. **Drying times can be shortened by cutting fruit into slices.
Table 2. Home Drying of Vegetables (cont.) For portable dehydrators, set temperature at 140 F. Sun drying requires temperatures of 98 to 100 F (Not recommended in humid climates)
Blanching Drying Time Time Vegetable Preparation Method (minutes) Method (hours) -------------------------------------------------------------------------------------------------------- Asparagus Wash thoroughly. Halve large tips. Steam 4-5 dehydrator 6-10
Water 3 1/2 - 4 1/2 sun 8-10 Beans, green Wash thoroughly. Cut in short Steam 2-2 1/2 dehydrator 8-14 pieces or lengthwise. Water 2 sun 8-10
Beets Cook as usual. Cool; peel. Cut into Already cooked; no --- dehydrator 10-12 shoestring strips 1/8 inch thick. further blanching sun 8-10
Broccoli Trim, cut as for serving. Wash Steam 3-3 1/2 dehydrator 12-15 thoroughly. Quarter stalks Water* 2 sun 8-11 lengthwise.
Brussels Cut in half lengthwise through Steam 2 1/2-3 dehydrator 12-18 Sprouts stem. Water 1 1/2-2 sun 9-11
Cabbage Remove outer leaves; quarter and Steam until wilted. 2 1/2 -3 dehydrator 10-12 core. Cut into strips 1/8 inch thick. Water. 1 1/2 -2 sun 6-7
Carrots Use only crisp, tender carrots. Wash Steam 3-3 1/2 dehydrator 10-12 thoroughly. Cut off roots and tops; Water 3 1/2 sun 8 preferably peel, cut in slices or strips 1/8 inch thick.
Cauliflower Prepare as for serving. Steam 4-5 dehydrator 12-15 Water* 3 1/2 sun 8-11
Celery Trim stalks. Wash stalks and leaves Steam 2 dehydrator 10-16 thoroughly. Slice stalks. Water 2 sun 8
Corn on the Husk, trim. Steam until milk does 2-2 1/2 dehydrator 12-15 Cob not exude from kernel 1 1/2 sun 8 when cut. Water
Corn, cut Prepare in the same manner as corn dehydrator 6-10 on the cob, except cut the kernels sun 6 from the cob after blanching.
Eggplant Use the same directions as for sum- Steam 3 1/2 dehydrator 12-14 mer squash. sun 6-8
Horseradish Wash; remove small rootlets and None dehydrator 4-10 stubs. Peel or scrape roots. Grate or sun 7-10 cut into 1/8-inch slices.
Mushrooms Scrub thoroughly. Discard any None dehydrator 8-10 (see tough, woody stalks. Cut tender sun 6-8 WARNING stalks into short sections. Do not below)*** peel small mushrooms or "buttons" Peel large mushrooms, slice.
Okra Wash, trim, slice crosswise in 1/8 to None dehydrator 8-10 1/4-inch disks. sun 8-11
Onions Wash, remove outer "paper shells" None dehydrator 10-20 Remove tops and root ends, slice sun 8-11 1/8 to 1/4-inch thick or dice.
Parsley Wash thoroughly. Separate clusters. None dehydrator 1-2 Discard long or tough stems. sun 6-8
Peas Shell. Steam 3 dehydrator 8-10 Water 2 sun 6-8
Peppers and Wash, stem, core. Remove "parti- None dehydrator 8-12 Pimientos tions" Cut into 3/8-inch disks. sun 6-8
Potatoes Wash, peel. Cut into shoestring Steam 6-8 dehydrator 8-12 strips 1/4 inch thick, or cut in Water 5-i sun 4-6 slices 1/8 inch thick. 8-11
Spinach and Trim, wash very thoroughly. Steam until thoroughly 2-2 1/2 dehydrator 8-10 Other wilted. sun 6-8 Greens (kale, chard, mustard)
Squash: Winter Cut or break into pieces. Remove Steam 2 1/2 dehydrator 10-16 seeds and cavity pulp. Cut into 1 Water 1 sun 6-8 inch-wide strips. Peel rind. Cut strips crosswise into pieces about 1/8-inch thick.
Summer Wash, trim, cut into 1/4-inch slices. Steam 2 1/2-3 dehydrator 10-12 Water 1 1/2 sun 6-8
Tomatoes, Dip in boiling water to loosen dehydrator 10-18 for stewing skins. Chill in cold water. Peel. Cut sun 8-10 into sections about 3/4 inch wide, or slice. Cut small pear or plum tomatoes in half. -------------------------------------------------------------------------------------------------------------- *Preferred method ***WARNING: The toxins of poisonous varieties of mushrooms are not destroyed by drying or cooking. Only an expert can differentiate between poisonous and edible varieties.
Reprinted by permission of the authors and the University of Wisconsin- Madison. For further information, contact your county Extension office; Bill,Evers or April Mason, Extension Foods and Nutrition Specialists, Purdue University, West Lafayette, Indiana.
Cooperative Extension work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agriculture cooperating: H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Cooperative Extension Service of Purdue University is an equal opportunity/equal access institution.