1. Drying Foods Jananne Finck, MS, RD. Nutrition & Wellness Educator
Springfield Center

2. 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

3. 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

4. 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

5. Helps Drying… Low humidity aids drying
Increasing air current speeds up drying, removes air around food

6. 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

7. 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

8. Out-Of-Doors Solar Drying Vine 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

9. 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

10. Drying Foods Indoors Food dehydrators Counter-top Convection ovens
Conventional ovens

11. 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

12. 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.

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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”

19. Pretreating the Fruit Sulfuring Sulfite Dip Ascorbic Acid
Ascorbic Acid Mixtures
Fruit Juice Dip
Honey Dip
Syrup Blanching
Steam Blanching

20. 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

21. 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

22. After Drying…
Cool fruit minutes before packaging…don’t pack too soon or moisture buildup could occur…don’t wait too long or could pick up moisture

23. 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

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

25. 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

26. 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

27. 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

28. Fruit Leathers
Fresh Fruit
Canned or Frozen Fruits

29. 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

30. 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

31. Eliminating E. coli O157:H7 Risk
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.
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.

32. 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.

33. Reference “So Easy To Preserve” Cooperative Extension Service
The University of Georgia, 4th Edition, 1999.