Drying Foods

Jananne Finck, MS, RD.

Nutrition & Wellness Educator

Springfield Center

Drying is New Again

One of the oldest methods of preserving food

Alternative to canning & freezing Simple, safe and easy to learn Can dry year round No refrigeration needed Takes little space

How Drying Preserves

Removes moisture from food so bacteria, yeasts & molds can’t grow and spoil food

Slows down action of enzymes but doesn’t inactivate them

Temperatures for Drying

Optimum temperature for drying food is 140°F

If higher temps are used, food cooks instead of drying

Avoid “case hardening” – dried outside and moisture is trapped inside – mold results

Helps Drying…

Low humidity aids drying Increasing air current speeds up drying,

removes air around food

Ways To Dry Food

Foods can be dried in the sun, but often doesn’t work well in Illinois…need several days of high temp and low humidity

Dry in an oven Dry in food dehydrator

Drying Out-Of-Doors

Sun Drying Dry fruits, high sugar & acid make them safe Don’t dry vegetables or jerky/meat outdoors Need hot, dry, breezy days Temp of 85ºF. or higher, for several days with

humidity below 60% Need to cover, watch materials used and

control for insects and pests

Out-Of-Doors

Solar Drying Need to make a dryer Need to stir and turn food several times a day Need several days…

Vine Drying Dry beans, lentils and soybeans Leave bean pods on vine until beans inside rattle If not dried can dry further in oven or dehydrator

Pasteurization

Freezer Method – seal food in freezer plastic bags. Freeze at 0ºF for at least 48 hours

Oven Method – Place food in single layer on fray or in shallow pan. Place in oven preheated to 160ºF for 30 minutes

Drying Foods Indoors

Food dehydrators Counter-top Convection ovens Conventional ovens

Food Dehydrators

Small electrical appliance for drying foods indoors

Electric element for heat & fat and vents for air circulation

Dry foods fast at 140ºF Buy at department stores, mail-order,

garden supply, internet

Costs?

Costs vary depending on features. Some are expandable & extra trays can be purchased. Twelve square feet of drying space dries about a half-bushel of produce.

Major disadvantage of dehydrator is limited capacity.

Dehydrator Features

Double wall construction of metal or high grade plastic, not wood

Enclosed heating element

Counter top design Enclosed thermostat

from 85ºF-160ºF

Fan or blower 4-10 open mesh trays,

plastic, sturdy, washable

UL seal 1 year guarantee Convenient service Dial for regulating temp A timer, auto- shut off

Types of Dehydrators

Horizontal Air Flow –

Heating element and fan are located on side

Major advantages – reduces flavor mixing so different foods can be dried at once, all trays get equal heat, juices don’t drip into heating element

Vertical Air Flow –

Heating element and fan located at base

Major disadvantage –

if different foods dried, flavors can mix and liquids can drip into heating element

Oven Drying

Slower than dehydrators, unless you have a convection oven, which has a fan

Take 2 times longer to dry in oven than dehydrator…oven not as efficient and uses more energy

Using Your Oven

Dial needs to go down to 140ºF Leave oven door propped oven 2-6 inches Best if you place a fan outside oven door Oven temp varies…so need accurate oven

thermometer to be sure 140 is achieved Trays should clear sides of oven & 3-4”

shorter front to back of oven, 2-3” between racks in oven

Room Drying

Herbs, hot peppers, & nuts in shell are most common air dried foods

Herbs & peppers – strung on string or tied in bundles and suspended from overhead racks in air until dry.

Can enclose in paper bags, with openings for air circulation

Spread nuts in single layer on paper

Drying Fruit

Preparing the Fruit – wash fruit and core, if needed

Fruits can be halved or sliced and some left whole Thin, uniform, peeled slices dry fastest Apples can be cored and sliced - wedges, rings Bananas can be sliced If fruit dried whole, “check” or crack the skin to

speed drying – cranberries – place in boiling then cold water to “check”

Pretreating the Fruit

Sulfuring Sulfite Dip Ascorbic Acid Ascorbic Acid

Mixtures

Fruit Juice Dip Honey Dip Syrup Blanching Steam Blanching

Drying the Fruit

Place fruit in single layer Follow directions given Follow approximate drying times given Watch food as it dries much faster at the

end of drying period

Determining Dryness of Fruit

Most fruit – should have 20% moisture content when dried

Cut several cooled pieces in half…should be no visible moisture and should not be able to squeeze any moisture from fruit

Not be sticky or tacky If piece folded in half, shouldn’t stick to

itself

After Drying…

Cool fruit 30-60 minutes before packaging…don’t pack too soon or moisture buildup could occur…don’t wait too long or could pick up moisture

Conditioning Fruits

Conditioning equalizes the moisture. Pack cooled fruit in plastic or glass jars,

seal and let stand for 7-10 days Shake jars daily to separate pieces and

check for moisture condensation If condensation, return to dehydrator for

more drying…unless has started to mold, then dispose of

Drying Vegetables

Preparing the vegetables Wash, trim, peel, according to directions Uniform pieces Dry as soon as possible after picking

Pretreating Vegetables

Water blanching – follow times given, start counting time as soon as water returns to boil. If takes more than 1 minute to return to boil, are putting in too many vegetables at a time

Steam blanching – Vegetables should be no more than 2 inches deep above boiling water. Cover and steam according to directions given for each vegetable

Cooling Vegetables

Dip briefly in cold water only long enough to stop cooking

Cool to they feel only slightly hot to touch…about 120ºF

Wipe vegetables and place in dehydrator

Determining Dryness of Veggies

Dry vegetables until brittle or “crisp” Some vegetables shatter if hit with

hammer 10% moisture Don’t need conditioning like fruits, as

lower moisture content

Fruit Leathers

Fresh Fruit

Canned or Frozen Fruits

Drying Fruit Leathers

Pour 1/8-inch thick on drying tray Take 6-8 hours to dry in dehydrator, up to 18 in

oven Dry at 140ºF Dry when no indention in center of leather When warm, peel from plastic and roll , cool and

rewrap roll in plastic Keep up to 1 month at room temp, then may

freeze up to 1 year

Jerky

Lean meat like beef, pork, venison or smoked turkey breast

If wild game is used, treat to kill Trichinella parasite by freezing a portion 6 inches or less thick at 0ºF at least 30 days…this doesn’t kill bacteria though

Eliminating E. coli O157:H7 Risk

Heating meat strips in marinade before drying – drying times will be reduced. Check temp of several strips with metal stem-type thermometer to determine 160ºF is reached.

Heating dried jerky strips in oven after drying process is completed. Heat strips 10 minutes in oven preheated to 275ºF. Thicker strips may take longer heating, check temp (160ºF) with thermometer.

Storing Jerky

Properly dried jerky keeps at room temp for 2 weeks in sealed container.

For best results, to increase shelf life and maintain best flavor and quality, refrigerate or freeze jerky.

Reference

“So Easy To Preserve”

Cooperative Extension Service

The University of Georgia, 4th Edition, 1999.