CFS-146-W

Drying Foods at Home

Food dehydration is a method of preserving food that fits today's lifestyles. Dryingfood offers one of the most economical and energy-efficient ways of preserving avariety of foods. It is estimated that drying costs less than canning and one-quarteras much as freezing.Drying not only preserves foods but also offers new and different nutritious snackssuch as dried fruits, fruit rolls, and meat jerkies.

Consumer and Family Sciences Department of Foods andNutrition

Purdue Extension

Consumer and Family Sciences

How drying works as apreservative

The purpose of drying is to preserve food bylowering the amount of water or moisture in thefood material to a point where microbial growth(bacteria, yeast, and mold) and chemical reac-tions (enzymatic deterioration) cannot destroy thefood during storage. Though drying itself doesnot destroy enzymes, the dried food (especiallypretreated dried food) is considered to be lowenough in moisture to prevent enzymaticdeterioration.

Because drying removes moisture, the foodshrinks and becomes lighter in weight and thus iseasier to store. When food is ready to use, thewater is added back and the food returns to itsoriginal shape and form.

The heat used in drying is generally at a lowtemperature (120° to 150°F). If higher tempera-tures are used, the food cooks rather than dries.When the temperature is too high, the food cookson the outside and the moisture cannot escape,causing “case hardening” and molding of thefood. The drying process should never be hurriedby raising the temperature during drying.

Low humidity aids the drying process,especially if the food naturally contains a lot ofwater. To dry food, the water must move from thefood to the surrounding air. If the surrounding airis humid, drying of the food will be sloweddown.

Air currents speed up drying by moving thesurrounding moist air away from the food surfaceand drawing fresh dry air into contact with thefood.

Foods can be dried by two general procedures:indoor or outdoor drying. Foods dried byindoor drying can be dried in an oven, a fooddehydrator, or by the air. In outdoor drying, thefood is dried directly in the sun, by a solar drier,or on the vine. Outdoor drying is not recom-mended in Indiana and other Midwestern states,because complete drying cannot be assured andthe end quality of the food is questionable. Alldrying methods requite the same essentialguidelines of warm temperatures, low humid-ity, and an available air current.

General drying proceduresWhen selecting foods for dehydration, choose

only foods that are in prime condition and

Adapted byApril C. Mason. Ph.D.;William D. Evers, Ph.D.,RD;and Erin Hanley, RD

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perfectly fresh, just as you would for any othermethod of preservation.

Although drying foods prevents microbialgrowth, certain chemical reactions caused byenzymes can still occur unless the product ispretreated before drying. Fresh produce, forexample, contains many different enzymes thatcause loss of color and loss of nutrients and flavorchanges in dried vegetables and fruits. Theseparticular enzymes must be inactivated by pretreat-ing the food to prevent such reactions from takingplace during the drying of the food.

Enzymes in vegetables are inactivated by theblanching process, which exposes vegetables toboiling water or steam for a brief period of time.Blanched vegetables, when dried, will have bettercolor and flavor than unblanched.

The major problem associated with enzymes infruits is the development of brown colors and theloss of vitamins A and C. Fruits are not blanchedlike vegetables because the blanching processgives them a cooked flavor. Instead, the enzymesin fruits are inactivated by using chemical com-pounds that interfere with deteriorative chemicalreactions. The most common control chemicalused is ascorbic acid (vitamin C). Ascorbic acidmay be used in its pure form or in mixtures ofascorbic acid with citric acid and/or sugar. Sodiumbisulfite is no longer recommended as a pretreat-ment chemical due to the increased number ofpeople reporting sensitivities to sulfiting agents.

Dehydration processesIndoor Drying Methods

Food Dehydrators. A food dehydrator is a smallelectrical appliance for drying foods indoors. Mostfood dehydrators have an electric element for heatand a fan and vents for air circulation. Efficientdehydrators are designed to dry foods rapidly anduniformly. They vary in cost from $50 to $300,depending on features. Some models are expand-able so that additional trays can later be purchased.In general, 12 square feet dries a half-bushel ofproduce.

There are two basic designs for dehydrators:One has horizontal airflow and the other verticalairflow. The major advantages of horizontal floware that it reduces flavor mixture, several different

foods can be dried at one time, all trays receiveequal heat penetration, and juices or liquids do notdrip down into the heating element. The heatingelement and fan are on the side.

Vertical airflow has the heating element and fanlocated at the base. If different foods are dried,flavors can mix, and liquids can drip into the base.

Dehydration of various fruits and vegetables atthe University of Wisconsin-Madison, using the twotypes of dehydrators, has shown a difference in thefinal product depending on the type of dryer used.The vertical dryer usually dried food faster butreadily over-dried the food if dried according tostandard recipe specifications.

Helpful hints for using a food dehydrator:

• Spray trays with a nonstick pan coating sprayto avoid sticking.

• Place food in a single layer. Avoid overlapping.

• Cut food in uniform sizes, shapes, and thick-ness.

• If the heat source and fan are at the bottom, thearomas will mix, so dry similar flavored foods.Horizontal fans and heat do not mix aromas.

• It is best not to dry strong-smelling foods suchas onions and garlic in the home. The odorsmay linger in drapes, clothes, and furniture.Place the dehydrator in a carport or coveredporch or patio. Protect the dehydrator from therain.

• Near the end of the drying period, observe thefood closely to avoid scorching.

The suggested temperatures for dehydrators withtemperature control are:

Herbs 95°FVegetables 125°FFruits, fruit leathers 135°FJerkies 145°F

Portable dehydrators can be used on a 110/120-volt general-purpose circuit (15 AMP). Whendrying a particular food, follow the recipe accompa-nying the commercial dehydrator closely for asuccessfully dehydrated product.

Oven Drying. Everyone who owns an oven ownsa food dehydrator. By combining the three factorsdiscussed earlier — heat, low humidity, and aircurrent — an oven can be used as a dehydrator.

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An oven is ideal for occasional drying of meatjerkies, fruit leathers, and banana chips or forpreserving leftovers like celery or mushrooms.Because the oven is needed for cooking, it may notbe satisfactory for preserving abundant gardenproduce.

Drying in an oven is slower than in a dehydratorbecause ovens do not have built-in fans for the airmovement (however, some convection ovens have afan). It takes two to three times longer to dry foodin an oven than in a dehydrator. Thus, the oven isnot as efficient as a dehydrator and uses a great dealmore energy.

To use your oven, check the oven dial to see if ithas a reading as low as 140°F. If the thermostatdoes not go this low, your food will cook instead ofdry.

For air circulation, leave the oven door proppedopen 2 to 4 inches. Place a fan near the outside ofthe oven door to improve circulation.

Because the door is left open, the drying tempera-ture will vary. An oven thermometer placed near thefood gives an accurate reading of the dryingtemperature. Adjust the temperature dial to giveproper heat. Ovens can be heated 20 degrees higherthan the recommended drying temperature andlowered to the suggested temperature after 2 hours.

Place food on wire racks 2 to 3 inches apart forproper air circulation.

Air Drying. This drying method differs from sundrying, since it takes place indoors in a well-ventilated attic, room, or screened-in porch. Herbs,hot peppers, and mushrooms are the most commonair-dried items.

Herbs and peppers are not pretreated, but aresimply strung on a string or tied in bundles andsuspended from overhead racks until dry. Enclosethem in paper bags to protect them from dust, looseinsulation, or other pollutants.

Microwave Drying. Drying food successfully ina microwave oven is not possible, except for herbsand some leaf vegetables. Food that has beenmicrowave dried tastes overcooked rather thandried. To dry herbs and leaf vegetables in a micro-wave, follow instructions in a microwave cook-book, or on page 10 of this publication.

Dehydrofreezing. Dehydrofreezing is a methodof food preservation that combines the techniquesof drying and freezing. Fruits or vegetables driedat home have had 85 to 90 percent of their mois-ture removed to prevent mold growth. However,by removing only 70 percent of the moisture andstoring the fruit or vegetable in the freezer, a tastierproduct results. The freezer's low temperatureinhibits microbial growth.

Fruits and vegetables processed this way havegood flavor and color and reconstitute in about halfthe time it takes for dried foods.

This process is not freeze drying, which is acostly commercial technique that forms a vacuumwhile the food is freezing and is not available forhome use.

Outdoor Drying Methods

Sun Drying. The high sugar and acid content offruits make them relatively safe to dry outdoors.Sun-dried raisins are the best known of all driedfoods. The San Joaquin Valley in Californiaproduces the world's largest supply of raisins. Thewarm temperature, low humidity, and constantbreeze in the valley are ideal conditions for dryinggrapes.

High humidity or low drying temperatures areconditions that could halt the drying process, thusallowing favorable surroundings for the food tomold or rot before it is dried. For these reasons,outdoor drying of foods is not recommended inIndiana and other Midwestern states.

All foods dried outdoors also need a pasteuriza-tion treatment following drying to kill insects andtheir eggs. Unless destroyed, the insects will eatthe dried food.

There are two recommended pasteurizationmethods:

Freezer Method. Seal the food in a plasticfreezer bag, place in a freezer set at 0°F or belowand hold for at least two days (48 hours).

Oven Method. Place the food on a tray or in ashallow pan and put in an oven preheated to 140°to 160°F for 30 minutes. Spread the food in asingle layer when pasteurizing and package it assoon as possible following the brief heat treatment.

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Solar Drying. Efforts to improve on sun dryinghave, in recent years, led to what is known as solardrying. Solar drying still uses the sun as the heatsource, but a specially designed container in-creases the temperature and air current to speed updrying. The shorter drying time reduces the risk offood spoilage or molding.

Solar driers use a reflectant such as aluminumfoil or glass to increase the sun's temperature from85-100°F to 105-130°F. Air movement is increasedby using air vents at each end. Cooler air enters thedryer, crosses the food, removes moisture, andescapes. Plastic covers the frame and prevents rainor condensation from dampening the food. Screensover the vents keep insects and birds off the food.

Solar dryers may need turning or tilting through-out the day to capture the direct, full sunlight.Food on the shelves needs to be stirred severaltimes a day. Again, the food must be pasteurizedprior to storage.

Vine Drying. Another method of dryingoutdoors is drying on the vines. To dry beans(navy, kidney, butter, great northern, lima, lentils,and soybeans), leave bean pods on the vine in thegarden until the beans inside rattle. When the vinesand pods are dry and shriveled, pick the beans andshell them. No further treatment is necessary. Ifbeans are still moist, the drying process is notcomplete and the beans will mold if not morethoroughly dried. If needed, drying can be com-pleted in an oven or a dehydrator. Pasteurization isneeded for those beans dried entirely in the sun.

Determining dryness of foodDrying food is a slow process. Solar drying

takes one to two days. It will take six or morehours to dry foods in a dehydrator and eight ormore hours in your oven. Drying time depends ontype of food, thickness, and type of dryer. Don’t betempted to speed up the drying time by increasingthe temperature. You will end up cooking the foodon the outside before it dries on the inside. This iscalled “case hardening.” While the food mayappear dry on the outside, it can be moist on theinside. Moisture left in the food will cause the foodto 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, cutthrough the center of the thickest part. There shouldbe no visible signs of moisture. A darker, wetinterior indicates the need for extended dehydration.

To test for doneness, remove a piece of foodduring the end of the drying period. Cool to roomtemperature and check for the following signs:

• Fruit is pliable, springy, and will not sticktogether if folded (figs and cherries may be sticky).

• Vegetables are brittle and would shatter if hitwith a hammer

• Meats are very dry. Jerky is dark, fibrous, andforms sharp points when bent.

• Herbs are brittle.

• Fruit leathers are dry to the touch. Fruit peelsaway from plastic wrap.

Packaging and storingDried foods must be properly stored to maintain a

low moisture content and to prevent microbialdeterioration. Before packing the foods, allow thedried pieces to cool. After the product has cooled,the food should be allowed to equilibrate for 5 to 10days before storing. Place food in a coveredcontainer and recheck each day to see if the productis sufficiently dry; if not, dehydrate longer.

To store dried foods, pack them in clean, dry,insect-proof containers as tightly as possiblewithout crushing. A recommended dry storagemethod is to place the dried food in plastic bags,press out air, seal or close and place in tightlysealed glass jars. Old peanut butter, mayonnaise, orother one-trip jars are recommended for storage ofdried food.

To be sure that the food remains dry, add desic-cant or silica gel, which are available in the notionsor housewares section of department stores or athobby shops. Place the substance in the glass jar tocover the bottom of the container to a depth of 1/4inch. The desiccant absorbs any moisture from thesurroundings and prevents the food from absorbingmoisture. Place the dried food wrapped in a closedplastic bag over the desiccant and tightly seal thejar.

Packaged dried food should be stored in a dry,cool place at about 60°F. Because food quality isaffected by heat, the storage temperature helps

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determine the length of storage; the higher thetemperature, the shorter the storage time. Anacceptable storage area in winter may be too warmin the summer. Keep dried food out of the sun toprevent discoloration and nutrient loss. Some driedfoods can also be stored successfully in the refrig-erator or freezer.

Foods that are packaged seemingly “bone dry”can spoil if moisture is reabsorbed during storage.Check dried foods frequently during storage to seeif they are still dry. Foods affected by moisture butnot spoiled should be used immediately or redriedand repackaged. Moldy foods should be discarded.

Rehydration of dried foodsWater removed during drying must be replaced

either by soaking, cooking, or a combination ofboth.

Dried vegetables need about two hours soakingtime before cooking. When you soak or rehydratethe vegetables, they should plump to nearly thesame size they were when fresh. Start with 11/2 to 2cups water for each cup of dried vegetables. Ifnecessary, add more water during the soakingprocess.

Soak root, stem, and seed vegetables for 1/2 to 2hours in sufficient cold water to keep them covered(soaking in too much water may cause over-softening of vegetables). After soaking, simmeruntil tender, allowing excess water to evaporate.Greens, cabbages, and tomatoes do not need to besoaked. Simply add sufficient water to keep themcovered and simmer until tender. Many vegetableslose their fresh flavor during drying. For thisreason, flavorings such as basil, garlic, onions, andchili sauce may be added during cooking toimprove flavor. Cook the vegetables in the samewater in which they have soaked to save nutrients.Dehydrated vegetables are usually not used ascooked side dishes. They are best when used asingredients for soups, casseroles, sauces, stuffings,and stews.

Dried fruits can be eaten or used in recipes asthey are. If you wish to plump or soften the fruitslightly to make it more chewable, you can use oneof these methods:

• Cover the dried fruit with boiling water, let itstand for five minutes and drain.

• Place the dried fruit in the top of a steamerover boiling water and steam three to five minutesuntil the fruit is plump.

Foods you should not dry athome

Milk, eggs, fish, and poultry are not recom-mended for home drying. Salmonella and Staphy-lococcus bacteria, which thrive on these foods, cansurvive and grow at low temperatures used to drymeat and dairy products. These bacteria grow veryrapidly in such products because all the nutrientneeds of these pathogenic or disease-producingbacteria are supplied by poultry, eggs, and dairyproducts.

Salmonella and Staphylococcus in home-driedfoods have caused food poisoning outbreaks.

Nutritive value of driedfoods

The nutritive value of dried foods, like that offoods preserved by canning and freezing, dependslargely on the care exercised in preparation,processing, and storage. Some of the sugars, saltsand water-soluble vitamins are lost during prepara-tion. Some of the volatile oils and esters andreadily oxidizable substances such as ascorbic acid(vitamin C) are lost during the drying process. Thevitamin A content of vegetables decreases duringstorage. The loss of this vitamin is greatest inunblanched vegetables. Carbohydrates, minerals,and proteins are concentrated but are otherwiseunaffected by drying. Further loss of nutrients canoccur during storage unless the foods are properlypackaged and sorted.

To keep the nutritional losses to a minimum,package dried foods in airtight containers, storethem at the lowest temperature possible, andconsume them within several months to a yearafter processing.

For those who follow the diabetes eating plan orother reduced-fat and reduced-calorie eating plans,dried fruits may satisfy a craving for sweets.However, be careful to consume only the amountequal to the fresh fruit exchange or serving. Dryingremoves water, not calories or sugar.

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Drying fruitsDried fruits are unique, tasty, and nutritious. It

might be argued that they are even tastier thanfresh fruits, and some people call them nature’scandy. They taste sweeter because the water hasbeen removed, thus concentrating the fruit’s flavor.Dried fruit can be eaten as a snack or added tocereals, muffins, or ice cream.

Preparing the Fruit

There are many ways to slice fruit for drying.Thin, even, peeled pieces dry the fastest. The peelcan be left on the fruit, but it will take longer todry. Use a food processor for uniform, even slices.

Because fruits contain sugar and are sticky,spray the trays with nonstick pan coating spraybefore placing fruit on them. After the fruit driesfor one to two hours, lift each piece gently with ametal spatula and turn.

Fruits dried whole take the longest to dry. Skinsneed to be cracked to speed up drying.

Pretreating the Fruit

Many fruits will darken rapidly after peeling dueto oxidation, but there are several ways to preventthis color change:

Antioxidants

Ascorbic acid (vitamin C) is effective inpreventing oxidation of most fruits. Ascorbic acid,in crystalline or tablet form, is available atdrugstores. One teaspoon weighs about threegrams (3,000 milligrams). Use 1/2 teaspoon perquart of water as a dip to hold sliced peaches,apples, pears, or similar fruits while you get themready for drying. Ascorbic acid may be addeddirectly to fruit purees.

Ascorbic-citric acid mixture (A-C-MEverfresh*). Available in many supermarkets; canbe used to prevent darkening. Use according tomanufacturer's directions.

Ascorbic acid-sucrose mixture (Fruit-Fresh*).This product, available in supermarkets, is anotheranti-darkening product that should be used

according to manufacturer's directions. Because theascorbic acid is diluted by the presence of sugar inthe mixture, larger amounts than pure ascorbic acidare needed.

Lemon juice or citric acid can help preventdarkening of some fruits, but they are not aseffective as ascorbic acid. One tablespoon of lemonjuice per quart of water can be used as a dip. Theremay be a slight but usually unobjectionable flavorchange.

Simply dipping the fruits into a fruit juicecontaining vitamin C (ascorbic acid) will help keepthe natural color and prevent further darkening.Suggested fruit juices include orange, lemon,pineapple (may be diluted half strength with water),grape, or cranberry with added vitamin C.

Pour two cups fruit juice into a one- to two-quartbowl. Slice fruit and place immediately in the bowlof juice. Soak fruit for three to five minutes, drainand place on sprayed trays. Fruit juice can bereused; cover and store in refrigerator and usewithin one to two days.

Honey

Honey is a sweetened dip that coats fruit toprevent darkening. Many of the commerciallyproduced dried fruits are honey-dipped. Thismethod can be used at home. Honey-dipped fruitsare higher in calories.

Prepare the dip by dissolving 1/2 cup sugar in 11/2cups boiling water. Cool to lukewarm and add 1/2cup honey. Makes 21/2 cups. Dip fruit in smallbatches. Allow to soak three to five minutes.Remove with slotted spoon and drain.

Hot Syrup

This is another type of sweetened dip. Combine 1cup each of corn syrup, sugar, and water. Bring toboil, add fruit, simmer 15 to 20 minutes and drainwell. Place on sprayed trays and lift fruit gently.Syrup dip increases drying time. This product islike a candied fruit. For further recommendationson specific fruit pretreatment, see Table 1.

Drying Temperature

Fruits are generally dried at 140°F for varyinglengths of time. Preheat the oven or dehydrator to160°F. Load trays. After two hours, decrease thetemperature to 140°F. Drying times vary. Fruits aresoft and pliable and not tacky when dry. Banana

* References to products in this publication are foryour convenience and are not an endorsement of oneproduct over similar products. You are responsible forusing products according to the manufacturer’s currentlabel directions.

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and apple chips can be dried until they are crisp.For recommended drying times, see Table 1(remember to follow drying times specified for yourcommercial dehydrator, if available).

Drying vegetablesVegetables contain less carbohydrates and dry

faster than fruits. Drying is an excellent way topreserve potatoes, onions, and green or red peppers.Unused celery or mushrooms can be preserved forlater use by drying.

For vegetables, drying time is crucial to tender-ness. The longer the drying time, the less flavorfuland the poorer the product. Drying time can behastened by drying small uniformly cut pieces. Toachieve this, use a food slicer or food processor.

Vegetables also have a lower moisture contentthan fruits; therefore, a lower dryer temperature of125°F is needed (tomatoes and onions with morewater can be dried at 140°F).

Vegetables dry much faster than fruits. Also, asthe drying period ends, they give up moisturerapidly. Vegetables will scorch if too high atemperature is used and if dried too long. They willbe brittle when dried.

Preparing Vegetables

Wash vegetables in cool water to remove soil.Trim and peel, then cut, slice, or shred. Remove anyfibrous or woody portions and core when necessary,removing all decayed and bruised areas. Keeppieces uniform in size so they will dry at the samerate, and prepare only as many as can be dried atone time. Holding vegetables, even in the refrigera-tor, after washing and preparation for drying willresult in loss of quality and nutrients. Dry veg-etables immediately after harvesting.

Pretreating Vegetables

Blanching is a necessary step in preparingvegetables for drying. It stops the enzyme actionthat causes loss of color and flavor during dryingand storage. It also sets the color and shortens thedrying and rehydration time by relaxing the tissuewalls so moisture can escape or enter more rapidly.By definition, blanching is the process of heatingvegetables to a temperature high enough to destroyenzymes present in the tissue. In water blanching,vegetables are submerged in boiling water. In steamblanching, they are suspended above the boiling

water and heated only by steam. Water blanchingusually results in a greater loss of nutrients buttakes less time than steam blanching. Recom-mended blanching and drying times are shown inTable 2.

Water Blanching. Fill a large kettle two-thirdsfull of water, cover and bring to a rolling boil.Place vegetables in a wire basket or colander andsubmerge them in the water. Cover and blanchaccording to directions for each vegetable (Table2). If it takes longer than one minute for the waterto come back to a boil, too many vegetables wereadded. Reduce the amount in the next batch.

To stop blanching, see “Cooling Process” below.

Steam Blanching. Use a deep kettle with aclose-fitting lid and wire basket, colander or sieveplaced so steam will circulate freely around thevegetables. Place vegetables loosely in the basketno more than 21/2 inches deep. Add several inchesof water to the kettle and bring to a rolling boil.Place the basket of vegetables in the kettle. Makesure the water does not come in contact with thevegetables. Cover and steam according to direc-tions for each vegetable (Table 2).

Cooling Process. After blanching, dip thevegetables briefly in cold water, only long enoughto stop the cooking action; do not cool them toroom temperature. When they feel only slightly hotto the touch, they will be cooled to about 120°F.Drain the vegetables by pouring them directly ontothe drying tray and arrange them in a single layer.Then immediately place the tray in the preheateddehydrator. The heat left in the vegetables fromblanching will cause the drying process to beginmore quickly.

Dried food specialties: Fruitleathers

Fruit leather is made by drying thin layers ofpureed fruit or leftover fruit pulp in the oven, sun,or dehydrator. While most fruits or fruit combina-tions can be used for making fruit leathers,grapefruit and lemons are not recommendedbecause they turn bitter when dried.

Some references for preparation of fruit leathersuggest heating the fruit before drying to stopenzymatic action, help preserve the fruit’s naturalcolor, and speed the drying process. Other refer-

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use waxed paper or aluminum foil, as you may endup eating them with your fruit leather. Spread thefruit concentrate evenly over the surface of the panto a depth of no more than 1/4 inch. Two cups pureeis 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 racksin the oven and leave door cracked open about twoto six inches, depending on oven door. Checktemperature of oven periodically with thermometer.If necessary, turn oven off for short time if tempera-ture is too high. The fruit concentrate should dry infour to 10 hours. Test frequently for dryness (See

“Test for Dryness” section below).

Dehydrator Drying. Place sheets ortrays of fruit concentrate in dehydrator.Set temperature control at 140° to150°F or follow manufacturer’sdirections. Test frequently fordryness. Drying time will be four to10 hours.

Test for Dryness. Properly driedfruit leather will be translucent and

slightly tacky to the touch, but easilypeeled from the pan or plastic wrap.

After loosening the edge of the leatherfrom the plastic wrap or pan, loosely roll

the leather in plastic wrap or waxed paper in onepiece.

Storage. Store fruit leather in a cool, dry, darkplace. It will keep up to a year or more in thefreezer, several months in the refrigerator, or a fewweeks at room temperature (70°F). Storage timeusually reflects surrounding conditions (tempera-ture fluctuation in refrigerator or freezer) and mayinfluence shelf life one way or another.

Dried food specialties:Yogurt leathers

Yogurt leather is made by drying layers of plainor fruit-flavored yogurt in a dehydrator. Followgeneral drying directions for fruit leathers. Preheatdryer to 120°F, put tray of yogurt in dehydrator, andraise temperature to 125°F to compensate for initialtemperature drop. Lower temperature to 120°Fapproximately one hour after placing tray in dryer.Check for doneness after four to five hours.Doneness test is similar to fruit leathers.

ences simply recommend blending the fresh fruitwith an antioxidant and drying the puree as is.Both methods are given below.

Preparation

Uncooked Method. Select ripe or slightly over-ripe fruit. Sort and wash, removing blemishes ordefective parts of acceptable fruit. Peel apples,oranges, peaches, pears, and tomatoes, if desired.Pit and core fruit as needed. Remove seeds fromgrapes, if desired. Hull strawberries. Cut fruit intochunks and place in food chopper or blender.

Add 1/2 to 1 tablespoon lemon juice or 1/4teaspoon pure ascorbic acid (ascorbicacid mixtures also may be usedaccording to label instructions) toeach 2 cups of light-colored fruit tohelp preserve natural color and slowenzymatic action.

Chop, grind, or blend fruit until athick puree is formed. One to 2tablespoons water may be added tohelp blend some fruits. You may alsowish to add 1 tablespoon of sugar, cornsyrup, or honey to each 2 cups of tart fruitsuch as pineapples or oranges. Additional sugar isnot needed for nontart fruit. A small amount ofspice (1/4 teaspoon or dash of nutmeg) or 1/4 cupsesame, pumpkin, or sunflower seeds may also beadded per 2 cups puree, if desired.

Cooked Method. Select, wash, peel, pit, andcore fruit as described for uncooked method above.Cut into slices or chunks and place in doubleboiler. Add water to bottom of double boiler.Cover and cook for 15 minutes or until soft. Crushfruit in a blender or food grinder. Addition of sugarand spices are optional, as described above.

Shortcut Canned Method. Substitute cannedfruit or baby food fruit (without tapioca) for thecooked fruit above. Canned applesauce andstrained baby food will not need to be pureed.Other canned fruits will need to be drained andpureed. Since canned fruits have been heatprocessed to stop enzymatic action, the addition ofascorbic acid is unnecessary.

Drying

Spray a cookie sheet or similar flat tray withvegetable spray or line with plastic wrap. Do not

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Drying meatsMeats need to be dried indoors at 145°F using a

dehydrator or oven. Jerky can be stored at roomtemperature for one to two months, but placing it inthe refrigerator or freezer extends its shelf life.

Meat Jerky

Jerky is a marinated meat, sliced thinly and dried.Marinades contain salt, oil, and an acetic liquidsuch as wine, vinegar, or lemon juice. Theseingredients are important because they slow downmicrobial growth during the long drying process.Do not omit any ingredient from the recipe.

A number of lean meats can be used to makejerky, including round steak, flank steak, sirloin tip,rump roast, or lean venison. Never use pork or bearas is, but first cook to 170°F internal temperature todestroy parasites that cause trichinosis. The use ofraw turkey and chicken is discouraged becausedrying does not destroy Salmonella (a disease-causing bacteria).

Preparation

Remove connective tissue and gristle from freshmeat. Trim off visible fat to prevent rancidity oroff-flavors during storage. Freeze meat until firm,but not solid.

Slice the meat into long, thin strips, 1/8 to 1/4 inchthick, 1 to 11/2 inches wide and 4 to 12 inches long.Most references recommend cutting with the meatgrain. Lay the strips out in a single layer on asmooth, clean surface. Flatten strips with heel ofhand or a rolling pin so they are fairly uniform inthickness.

Season the meat strips by rubbing in no morethan 1 teaspoon salt per pound of fresh meat. Addpepper, garlic and onion powder, favorite herbs, orother seasonings to taste. Curing salts are alsoavailable and often contain premixed spice mix-tures.

Jerky may also be seasoned by marinating forseveral hours. A recipe for seasoning with LiquidSmoke and two recipes for seasoning with mari-nades are given on this page.

Drying

Remove meat strips from marinade, if used, andpat dry with paper towels. Dry strips in the oven ordehydrator.

Oven Drying. Stretch strips across clean ovenracks or other drying trays. If any strips are tooshort, fasten several together with woodentoothpicks. Allow edges of the meat strips to touchbut not overlap. Leave enough open space on theracks for air to circulate around strips. Arrangeracks so that the top one is at least four inchesbelow the top heat source and the bottom rack is atleast four inches above the bottom heat source. Setoven temperature at 140° to 150°F and let stripsdry for about 11 hours, or until they are chewy andleathery.

Dehydrator Drying. Follow manufacturer’s oroven drying instructions.

Smoke Seasoning(seasons 2 pounds lean meat)2 tablespoons water1/2 teaspoon Liquid or Powdered SmokeSalt and pepper

Combine water and smoke flavoring. Brush mixture on bothsides of meat strips. Place the meat strips, layer on layer, in alarge bowl. Cover with a plate and put a weight on top.Refrigerate for at least two hours or overnight.

Spicy Marinade(seasons 2 pounds lean meat)l1/2 teaspoons seasoned salt11/2 teaspoons onion powder1/4 teaspoon black pepper1/2 teaspoon garlic powder1/4 cup soy sauce1/3 cup Worcestershire sauce

Combine seasonings, pour over meat strips, and mix gently.Cover and refrigerate for at least two hours or overnight. Stiroccasionally while refrigerating.

Teriyaki Marinade(seasons 2 pounds meat)1/4 cup soy sauce2 cloves garlic, crushed1 teaspoon freshly grated ginger root or 1/2 teaspoon

ground ginger2 teaspoons sugar1 teaspoon salt

Combine seasonings, pour over meat strips in a large bowl,and mix gently. Cover and refrigerate for at least two hours orovernight. Stir occasionally while refrigerating.

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Test for Dryness. Properly dried jerky is chewyand leathery. Be sure to test for dryness aftercooling; warm jerky will be pliable, even thoughenough moisture is removed.

When jerky is sufficiently dry, remove fromdrying area and blot up any drops of oil that haveaccumulated from marbled fat with paper towels.Cool. Serve, or store in an airtight container. Toomuch air causes off-flavors and rancidity.

Store containers of jerky in a cool, dry, darkplace or the refrigerator or freezer. Dried jerkymay be stored up to a year.

HerbsThe best time to harvest most herbs for

drying is just before the flowers openwhen they are in the bursting bud stage.Rinse herbs in cool water and shake toremove excess moisture. Discard allbruised, soiled, or imperfect leaves andstems.

Herbs with long stems such as marjoram, sage,savory, mint, and rosemary can be dried inbunches. Tie the stem ends together into smallbunches 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 herbsto remove the moisture without destroying the oils.If herbs are dried outside, bring them inside atnight to prevent them from reabsorbing moisture.To protect the herbs from dust and other airbornecontaminants, place each bunch inside a paper bag.Gather and tie the bag firmly around the stem endsso that the herb leaves hang freely inside the bag.Cut out the bottom of the bag or leave air holes inthe sides to provide ventilation.

Tray drying is best for seeds and large-leafedherbs such as basil and those with short-tipped

stems. Spread seeds or herbs one layer deep onscreens so air can circulate freely. If drying outside,cover trays with cheesecloth to protect herbs frombirds, insects, and airborne contaminants. Stir orturn herbs daily to ensure uniform and thoroughdrying.

Drying should be complete in one to two weeks,depending upon temperature and humidity. Whenleaves are crispy dry and crumble easily in thefingers, they are ready to be packaged and stored.Place herbs in airtight containers and store in cool,

dry, dark areas to protect color andfragrance.

Microwave ovens are a quickway to dry herbs when only smallquantities are to be prepared. Placeno more than four or five herbbranches between two paper towelsand put in the oven. Turn oven onfor two to three minutes. Removeherbs from oven and place them on a

rack for cooling. If herbs are not dryand brittle, repeat microwave drying

for 30-second intervals until dry. Prepareand store as for air-dried herbs.

ReferencesThomas, Theodore. Dried Fruit Leathers. 1983.

Cooperative Extension Service. WashingtonState University. Pullman, Wash.

Klippstein, R.N. and K.J.T. Humphrey. HomeDrying of Foods. 1982. Extension Service.Cornell University. Ithaca, N.Y.

Ybarra, P.W. Preserving Food: Drying. 1984.Cooperative Extension Service. University ofGeorgia. Athens, Ga.

Kendall, P. Leathers and Jerkies - Dried FoodSpecialties. 1978. Extension Service. ColoradoState University. Fort Collins, Colo.

Hertzberg, R., B. Vaughan and J. Green. PuttingFood By. 1982. The Stephen Green Press.Brattleboro, Vt.

Reynolds, S. and P.W. Ybarra. So Easy to Preserve.1984. Cooperative Extension Service. Universityof Georgia. Athens, Ga.

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Table 1. Home Drying of Fruits

Treat before drying withone of these methods(minutes) Drying times

Sun Dehy- Test forSteam Water Drying drator Dryness

Fruit Preparation Dipping Blanch Blanch (days) (hours) (cool first)

Apple 3-5* 3-5, - - 3-4 6-12 Soft, pliable, no moistarea in center when cut

Apricots 3-5* 3-4 4-5 2-3 23-36* Same as for apples

Bananas 3-5* N.R. N.R. 4-5 5-24 Light to medium brown,pliable to brittle

Figs No treatment necessary 4-5 12-20 Fresh, pliable, slightlysticky, but not wet

Grapes: Opt. Opt. 3-5 12-20 Raisin-like texture, noMuscat, moist centerTokay,or any-seedlessgrape

Nectarines 3-5* 8 8 3-5 36-48* Same as for applesandPeaches

Pears 3-5* 6 (peel- - - 5 24-36* Same as for applesed willbe soft)

Persimmons No treatment necessary 5-6 18-24 Light to medium brown,tender but not sticky

Prunes Opt. Opt. 4-5 24-36 Leathery: pit should notslip when squeezed ifprune not cut

*Preferred method**Drying times can be shortened by cutting friut into slices.

Peel and core, cut into slices or ringsabout 1/8 inch thick.

Pit and halve for steam blanch. Leavewhole for water blanch. Pit and halveafter water blanch.

In dry, warm, sunny climates, it ispreferable to partly dry on the tree.

Figs normally drop from the treewhen 2/3 dry. In coastal areas, pickfruit when ripe.

Grapes dry in less time if blanched1/2 to 1 minute.

For steam and water blanching,leave whole, then pit and halve.

Cut in half and core. Peelingpreferred.

Use firm fruit when using the longer,softer variety, and use riper fruitwhen using the round, drier variety.Peel and slice with stainless steelknife.

For sun drying, blanch in boilingwater or steam for 1 to 11/2 minutesto “check” skins. For oven drying,rinse in hot tap water. Leave whole.

dependingon texture

12

Table 2. Home Drying of Vegetables

For portable dehydrators, set temperature at 140°F.Sun drying requires temperatures of 98° to 100°F (Not recommended in humid climates.)

Blanching DryingVegetable Preparation Method Time Method Time

(minutes) (hours)Asparagus Steam 4-5 dehydrator 6-10

Water 31/2-41/2 sun 8-10Beans, green Steam 2-21/2 dehydrator 8-14

Water 2 sun 8-10Beets Already cooked; no further dehydrator 10-12

blanching sun 8-10Broccoli Steam 3-31/2 dehydrator 12-15

Water 2 sun 8-11Brussels Steam 21/2-3 dehydrator 12-18sprouts Water 11/2-2 sun 9-11Cabbage Steam until wilted 21/2-3 dehydrator 10-12

Water 11/2-2 sun 6-7Carrots Steam 3-31/2 dehydrator 10-12

Water 31/2 sun 8

Cauliflower Steam 4-5 dehydrator 12-15Water 3-4 sun 8-11

Celery Steam 2 dehydrator 10-16Water 2 sun 8

Corn on the cob Steam until milk 2-21/2 dehydrator 12-15does not exudefrom kernelwhen cut.Water 11/2 sun 8

Corn, cut dehydrator 6-10sun 6

Eggplant Steam 31/2 dehydrator 12-14sun 6-8

Horseradish None - - dehydrator 4-10sun 7-10

Wash thoroughly. Halve large tips.

Wash thoroughly. Cut in short pieces orlengthwise.Cook as usual. Cool. Peel. Cut intoshoestring strips 1/8 inch thick.Trim, cut as for serving. Wash thoroughly.Quarter stalks lengthwise.Cut in half lengthwise through stem.

Remove outer leaves; quarter and core.Cut into 1/8-inch strips.Use only crip, tender carrots. Wash thoroughly.Cut off roots and tops; preferably peel, cut inslices or strips 1/8inch thick.

Prepare as for serving.

Trim stalks. Wash stalks and leavesthoroughly. Slice stalks.

Husk, trim.

Prepare in same manner as corn on the cobafter blanching.

Wash, trim, cut into 1/4-inch slices.

Wash; remove small rootlets and stubs.Peel or scrape roots. Grate or cut into1/8-inch slices.

13

Reprinted by permission of the authors – Mary K. Wagner, Mary E. Mennes, and Clarence E. Johnson –and the University of Wisconsin-Madison. For further information, contact Bill Evers, Purdue foods and

nutrition Extension specialist.

REVIEWED 6/01

It is the policy of the Purdue University Cooperative Extension Service, David C. Petritz, Director, that all persons shall haveequal opportunity and access to the programs and facilities without regard to race, color, sex, religion, national origin, age, marital

status, parental status, sexual orientation, or disability. Purdue University is an Affirmative Action employer.This material may be available in alternative formats.

1-888-EXT-INFOhttp://www.agriculture.purdue.edu/AgComm/

Table 2. Home Drying of Vegetables (continued)

Blanching DryingVegetable Preparation Method Time Method Time

(minutes) (hours)Mushroom None - - dehydrator 8-10(See warning sun 6-8below)***

Okra None - - dehydrator 8-10sun 8-11

Onions None - - dehydrator 10-20sun 8-11

Parsley None - - dehydrator 1-2

sun 6-8Peas Steam 3 dehydrator 8-10

Water 2 sun 6-8

Peppers and None - - dehydrator 8-12Pimientos sun 6-8

Potatoes Steam 6-8 dehydrator 8-12Water 5-6 sun:

1/4" strips 8-11 1/8" slices 4-6

Spinach and Steam until 2-21/2 dehydrator 8-10other greens thoroughly sun 6-8(Kale, Chard, wiltedMustard)

Squash: Steam 21/2-3 dehydrator 10-12Summer Water 11/2 sun 6-8

Squash: Steam 21/2 dehydrator 10-16Winter Water 1 sun 6-8

Tomatoes, for dehydrator 10-18stewing sun 8-10

*** WARNING: The toxins of poisonous mushrooms are not destroyed by drying or cooking. Only an expert can differentiate between poisonousand edible varieties.

Scrub thoroughly. Discard any tough, woodystalks. Cut tender stalks into short sections. Donot peel small mushrooms or “buttons.” Peeland slice large mushrooms.

Wash, trim, slice crosswise in 1/8 to 1/4-inchdisks.Wash, remove outer “paper shells.” Removetops and root ends, slice 1/8 or 1/4 inch thick, ordice.

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

Shell.

Wash, stem, core. Remove “partistions.” Cutinto 3/8-inch disks.

Wash; peel. Cut into shoestring strips 1/4 inchthick, or cut in slices 1/8 inch thick.

Trim, wash very thoroughly.

Wash, trim, cut into 1/4-inch slices.

Cut or break into pices. Remove seeds andcavity pulp. Cut into 1 inch-wide strips. Peelrind. Cut strips crosswise into pieces about 1/8inch thick.

Dip in boiling water to loosen skins. Chill incold water. Peel. Cut into sections about 3/4inch wide, or slice. Cut small pear or plumtomatoes in half.

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