Drying Foods

Drying Foods
Drying Foods
Drying or dehydration, the oldest method of food preservation, is particularly
successful in the hot, dry climates found in much of New Mexico. Quite simply,
drying reduces moisture necessary for bacterial growth that eventually causes
deterioration.
Successful dehydration depends upon a slow steady heat supply to assure that
food is dried from the inside to the outside. Drying is also an inexact art. Size of
pieces, relative moisture, and the method selected all affect the time required to
dehydrate a food adequately.
Methods of Drying
Foods may be sun dried with or without a solar dehydrator, in a gas or electric
oven, or with a portable electric dehydrator. Dehydrators with thermostats provide
better control over poor weather conditions and food quality than sun drying.
An effective solar dehydrator is the shelf above the back seat of a car. Clotheslines
are another popular drying rack for ears of corn and strips of jerky. Colorful red
chile ristras hung from vigas are practical as well as decorative.
Sun drying. Prepared foods are placed on drying trays. Stainless steel screening
and thin wood lath are good materials for home-constructed drying trays. As
aluminum screening reacts with acids in the fruit, it is less desirable. Do not use
galvanized, copper, fiberglass, or vinyl screening.
Trays measuring about 14" x 24" x 1" are an easy size to handle. If trays are to be
used in an oven, they should be 1 1/2" smaller in length and width than oven
shelves to allow air circulation.
Place trays of food away from dusty roads and yards. Elevate them at least 1"
above the table with spools or bricks to allow good air circulation below the food.
Cover the food with a muslin or cheesecloth tent to protect it from insects. Dry
fruits and meats in direct sunlight; move trays periodically to assure direct sun
exposure. Place vegetables in the shade to prevent excessive color loss.
If rain threatens or food requires more than one day to dry, cover with a waterproof
material or place the food in a sheltered area.
To destroy insects or their eggs that may be on sun-dried foods and to remove
additional moisture in thicker pieces, heat foods in a 150 degree oven for 30 min.
Oven drying. Either build trays as described for sun drying or convert oven racks
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to drying racks by stretching muslin or cheesecloth across the oven rack. Secure
with toothpicks or long sewn stitches. Alternate trays in the oven periodically to
assure even drying.
Set oven control at its lowest setting, but not below 140-150 degrees. If using an
electric oven, wedge a potholder between oven and door to allow a 1" opening.
Moisture from the drying food will vent through this opening. Close the door on a
gas oven, as into vent will permit moisture to escape.
Dehydrator. There are two types of dehydrators: solar and electric. For each type
of dehydrator, prepare food and place on racks. If using a solar dehydrator, adjust
the position of the food throughout daylight hours to keep in direct sunlight.
Follow manufacturer's instructions for the electric dehydrators. When purchasing
an electric dehydrator, select one that has a thermostat to regulate temperature
and a fan to circulate air.
General Directions for Preparing Foods for Drying. Refer to the tables at the
end of this guide for instructions for specific foods.
Vegetables. Choose tender vegetables. Wash, remove any damaged areas, and
cut into even pieces. Blanch, then chill as though preparing for the freezer. Note:
Do not blanch mushrooms, onions, or sweet peppers.
To blanch in boiling water, use one pound of food for each gallon of boiling water.
Immerse vegetable into the boiling water using a wire basket or mesh bag, cover
kettle, and boil the recommended time (see table). Blanching water may be reused
until it becomes cloudy. Drain vegetables thoroughly.
To steam blanch, place 1" of water in kettle and bring to a rolling boil. Suspend thin
layer of vegetables in basket or loose cheesecloth bag. Cover and steam blanch
required amount of time (see table).
Fruit. Choose firm, mature fruit. Wash, peel if desired, remove any damaged
areas, and cut into even-sized pieces or slices. Some fruits require little or no
pretreatment. However, pretreat apples, apricots, bananas, cherries, peaches, and
pears by one of the following methods to reduce vitamin and flavor loss, browning,
and deterioration during storage.
Immerse fruit in a solution of one of the following to a gallon of water: 1 tbsp of
sodium bisulfate or 2 tbsp of sodium sulfite or 4 tbsp of sodium metabisulfite.
These pretreatment mixtures are available from some grocery stores, pharmacies,
and wine-making shops. Soak fruit pieces for 5 min. and fruit halves for 15 min.
Note: Approximately 5% of asthmatics are sensitive to sulfites. Use one of the
following pretreatments if sulfites present a potential health problem:
Dip fruit in a commercial ascorbic acid/water mixture from the grocery store. Follow
manufacturer's instructions when preparing and using the solution.
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Steam blanch fruit for 5-6 min.; water blanch fruit for 4-5 min. (see information on
water and steam blanching above).
Dip prepared fruit in a saline solution composed of 2-4 tbsp of salt and l gallon of
water for 10-15 min.
Meat. Choose lean cuts of beef or venison. Partially freeze and remove all visible
fat. Slice with the grain of the meat into strips, 1" wide, 1/2" thick and 8-10" long.
Pound strips flat to tenderize and season with salt, chile, or other desired flavors.
Marinate and refrigerate overnight for additional tenderness and flavor. Popular
marinades include teriyaki, sweet and sour, soy, Worcestershire, and chile sauces.
Fish. Slice salmon filets into thin strips. Place strips in a dish or enamel pan. Salt
strips using 2 tbsp. salt per pound. Refrigerate overnight. Oven or dehydrator
drying is preferable to sun drying fish.
Drying Times
Drying time varies widely because of the method selected and the size and
amount of moisture in food pieces. Sun drying requires the most time; an electric
dehydrator requires the least. Vegetables take from 4-12 hours to dry; fruits take 6-
20 hours. Meats require about 12 hours. Making raisins from grapes may require
days/weeks when dried outside.
When testing foods for dryness, remove a piece from the center of the drying tray
and allow it to come to room temperature. Fruits and meat jerky should be leathery
and pliable; vegetables should be brittle.
Conditioning Dried Foods
Food should be conditioned for a week before being packaged for long-term
storage. To condition food, place it in a container such as a cloth sack or a clear,
covered container and allowing any remaining moisture to redistribute itself
through the fruit.
If using a clear, covered container, watch for moisture beads. If they form, continue
drying food. If using the cloth bag, hang it in a convenient location and shake the
bag daily to redistribute food and moisture.
Storing Dried Foods
Place dried food in freezer-weight plastic storage bags, press out air, and then put
in containers with a tight-fitting lid. Store in a cool, dark, dry area.
Dried foods store well at room temperature for a month. Refrigerate foods if they
will be used within three months; freeze foods for storage periods between three
months and one year. Foods should be used within one year.
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Instructions for Specific Food Drying
VEGATABLES (See text for general directions)
Using Dried Foods
Dried meat, commonly called jerky, is normally not rehydrated and is eaten in the
dried state. Dried meats and vegetables used in soups rehydrate during the
cooking process.
Rehydrate vegetables by soaking them in 1 1/2-2 cups of water for each cup of
dried vegetable. If necessary, add more water during the soaking process. Heat
and eat.
Cover dried fruit with boiling water and let stand for 5 min. Drain. Dried fruit may
also be steamed for 3-5 min. until plump. Fruits may be eaten immediately or used
in a recipe.
Making Fruit Leather
Fruit leathers, also called fruit roll ups, can be made from almost all fruits or
combinations of fruits. However, peaches, apricots, cherries, and nectarines are
ideal. Pears and apples, sufficiently softened, also work well.
Wash well, peel (if desired), cut into pieces, and puree fruit in a blender. Sweeten
to taste with sugar or honey. Spread evenly, no more than 1/4" deep, on a cookie
sheet. The cookie sheet should either be lightly sprayed with a vegetable
shortening or covered with plastic paper.
If using plastic paper, tape edges down to prevent them from folding into the
puree. Dry fruit leather until it is slightly tacky to the touch.
When dried, lift leather (including plastic paper if used), and roll or cut into small
sections and roll. Storage recommendations are the same as those described
previously.
Nutritional Value of Dried Foods
Dried foods retain their protein, mineral and vitamin A content fairly well if soaking
water is also consumed. Because they are concentrated into a small mass, dried
foods can also be high in calories. It's important to brush teeth after eating dried
fruit because they stick to the teeth.
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Vegetable Preparation
Blanching
Time(mins.)
with Steam
Cooling Time
(mins.) with
Cool Water
Dryness Test
Asparagus
Wash
thoroughly.Halve
large tips.
4-6 4-5 Leathery to
brittle
Green Beans Wash. Cut in
pieces or strips. 2-3 2 Very dry brittle
Beets
Cook as usual.
Cool & peel. Cut
into shoe-string
strips 1/8" thick.
Included in
cooking
Included in
cooking
Brittle, dark
red
Broccoli
Trim, cut as for
serving Wash.
Quarter stalks
lengthwise.
3-4 2 Crisp, brittle
Brusselssprouts
Cut in half
length-wise
through stem.
7-8 5-6 Tough to
brittle
Cabbage
Remove outer
leaves quarter
and core. Cut
into strips 1/8"
thick.
3 2 Crisp to brittle
Carrots
Select crisp,
tender
vegetables.
Wash. Cut off
roots and tops,
peel. Cut in
slices or strips
1/8" thick.
3-4 4 Tough to
brittle
Cauliflower Prepare as for
serving. 5-6 4-5 Tough to
brittle
Celery
Trim stalks.
Wash stalks and
leaves
thoroughly, Slice
stalks.
2-3 2-3 Very brittle
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Green Chile
Peppers
Wash. To
loosen skins, cut
slit in skin, then
rotate over
flame 6-8 min.
or scald in
boiling water.
Peel and split
pods. Remove
seeds and stem.
None None Crisp, brittle,
medium green
Red Chile
Peppers
Wash. String
whole pods
together with
needle and cord
or suspend in
bunches, root
side up in area
with good air
circulation.
None None
Shrunken,
dark redpods,
flexible
Corn on the
Cob
Husk, trim,
blanch until milk
in corn is set.
3-5 3 Brittle
Corn, cut
Prepare as for
corn on the cob,
except cut the
kernels from the
cob after
blanching.
3-5 3 Brittle
Eggplant Wash, trim, cut
into 1/4" slices. 3-4 3-4 Leathery to
brittle
Horseradish
Wash, remove
small roots and
stubs. Peel or
scrape roots.
Grate.
None None Brittle,
powdery
Mushrooms
(see note
below)
Scrub. Discard
tough woody
stalks. Slice
tender stalks
1/4" thick. Peel
large
mushrooms,
slice. Leave
small
mushrooms
whole.
None None Dry and
leathery
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Onions
Wash, remove
outer
"papershells."
Remove tops
and root ends,
slice 1/8-1/4"
thick.
None None Very brittle
Parsley and
other herbs
Wash
thoroughly.
Separate
clusters. discard
long or tough
stems. Dry on
trays or hang in
bundles in area
with good
circulation.
None None Flaky
Peas Shell. 3-4 3
Hard,
wrinkled,
green
Peppers and
pimentos
Wash, stem.
Remove core
and seeds. Cut
into 1/4"-1/2"
strips or rings.
None None Tough to
brittle
Potatoes
Wash, peel. Cut
into 1/4" shoestring
strips or
1/8" thick slices.
7-9 6-7 Brittle
Spinach and
other greens
(kale, chard,
mustard)
Trim and wash
very thoroughly.
Shake or pat dry
to remove
excess
moisture.
2-3 (until
wilted) 2 Crisp
Squash,
winter
Cut or break into
pieces. Remove
seeds and cavity
pulp. Cut into 1"
wide strips. Peel
rind. Cut strips
crosswise into
pieces about
1/8" thick.
3 1-2 Tough to
brittle
Squash,
summer or
banana
Wash trim, cut
into 1/4" slices. 3 1-2 Leathery to
brittle
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Instructions for Specific Food Drying
FRUITS (See text for general directions.)
Tomatoes
Steam or dip in
boiling water to
loosen skins.
Chill in cold
water. Peel.
Slice 1/2" thick
or cut in 3/4"
sections.
None None Crisp
Fruit Preparation Pretreatment Drying Procedure
Apples
Wash. Pare, if
desired, and core.
Cut in rings or
slices 1/8-1/4" thick
or cut in quarters
or eighths Coat
with ascorbic acid
solution to prevent
darkening during
preparation (uses
2 1/4 tsp/cup
water).
Choose one: Soak
5 min in sodium
sulfite solution.
Steam-blanch 3-5
min., depending on
size and texture.
Arrange in single
layer trays, pit side
up. Dry until soft,
pliable and
leathery; no moist
area in center
when cut.
Apricots (firm, fully
ripe)
Wash. Cut in half
and remove pit (do
not peel). Coat
with ascorbic acid
solution to prevent
darkening during
preparation (1
tsp/cup).
Choose one: Soak
5 min. in sodium
sulfite solution.
Steam blanch 3-5
min.
Arrange in single
layer trays, pit side
layer up; pop the
cavity up to expose
more flesh to air.
Dry until soft
pliable and
leathery; no moist
area in center
when cut.
Bananas (firm,
ripe)
Peel. Cut in 1/8"
slices
No treatment
necessary; may
dip in lemon juice.
Arrange in single
layer on trays. Dry
until tough and
leathery.
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Berries (firm)
Wash. Leave
whole or cut in
half.
No treatment
necessary; may
dip in boiling water
15-30 sec., to
crack skins. Steam
blanch 30 sec. to 1
min.
Spread in layer not
more than two
berries deep. Dry
until hard and
berries rattle when
shaken on trays.
Cherries (fully ripe) Wash. Remove
stems and pits.
No treatment
necessary; may
dip whole cherries
in boiling water 15-
30 sec. crack
skins.
Arrange in single
layer on trays. Dry
until tough,
leathery and to
slightly sticky.
Citrus peel (thickskinned
with no
signs of mold or
decay and no color
added)
Wash. Thinly peel
outer 1/16-1/8" of
the peel; avoid
white bitter part.
No pretreatment
necessary.
Arrange in single
layers on trays.
Dry at 130 degrees
1-2 hours; then
120 degrees until
crisp.
Figs (fully ripe)
Wash or clean with
damp towel. Peel
dark-skinned
varieties if desired.
Leave whole if
small or partly
dried on tree; cut
large fig in halves
or slices.
No treatment
necessary; may
crack skins of
whole figs in
boiling water 15-30
sec.
Arrange in single
layer on trays. Dry
until leathery and
pliable.
Grapes (seedless
varieties)
Wash, sort, leave
whole on stems in
small bunches, if
desired, May also
remove stems.
No treatment
necessary; may
crack skins in
boiling water 15-30
sec. Steam blanch
1 min.
Spread in thin
layer on trays. Dry
until pliable and
leathery with no
moist center.
Melons (mature,
firm and heavy for
size: cantaloupe
dries better than
watermelon)
Wash. Remove
outer skin, any
fibrous tissue and
seeds. Slice 1/4-
1/2" thick.
No pretreatment
necessary.
Arrange in single
layer on trays. Dry
until leathery and
pliable with no
pockets of
moisture.
Peel. Cut in half Arrange in single
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Nectarines and
Peaches (ripe,
firm)
and remove pit.
Cut in quarters or
slices if desired.
Coat with ascorbic
acid solution to
prevent darkening
during preparation
(1-tsp/cup)
Choose one: Soak
5-15 min in sodium
sulfite. Steam
blanch halves 8-10
min., slices 2-3
min.
Arrange in single
layer on trays pit
side up. Turn
halves over when
visible juice
disappears. Dry
until leathery and
somewhat pliable.
Pears (Bartlett
variety is
recommended)
Wash. Pare, if
desired. Cut in half
lengthwise wash
and core. Cut in
quarters or eighths
or slice 1/8-1/4"
thick. Coat with
ascorbic acid
solution to prevent
darkening during
preparation (1-
tsp/cup)
Choose one: Soak
5-15 min. in
sodium sulfite.
Steam blanch 5-7
min.
Arrange in single
layer on trays pit
side up. Dry until
springy and suede
like with no
pockets of
moisture.
Plums and prunes
Wash. Leave
whole if small; cut
large fruit into
halves (pit
removed) or slices.
No treatment
necessary; may
choose: Steam
blanch halves or
slices 5-7 min.
Crack skins in
boiling water 1-2
min.
Arrange in single
layer on trays pit
side up, cavity
popped out. Dry
until pliable and
leathery; pit should
not slip when
squeezed if prune
not cut.
(1) Blanching times are for 3,000-5,000 ft. Times will be slightly longer at higher
altitudes, or if the quantity of vegetable is large.
(2) Dry in thin layers on trays to desired state of dryness.
(3)WARNING: The toxins of poisonous varieties of mushrooms are not destroyed
by drying or by cooking. Only an expert can differentiate between poisonous and
edible varieties.
By Alice Jane Hendley, Extension Diet and Health Specialist . New Mexico State
University is an equal opportunity/affirmative action employer and educator. NMSU
and the U.S. Department of Agriculture cooperating.