This document provides instructions for different methods of drying foods, including fruits, vegetables, and meats, as a method of food preservation. It discusses that drying removes moisture from food to prevent bacterial growth. The optimal temperature for drying is 140°F in a food dehydrator or oven to dry foods without cooking them. Various fruits and vegetables must be prepared and pretreated before drying, then dried until crispy or brittle indicating they reached about 10-20% moisture. Dried foods can be stored at room temperature or refrigerated for longer shelf life. Jerky made from lean meat must be heated to 160°F to eliminate bacteria risks.

1. Drying Foods

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
 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 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

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 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.

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.