Authors: Tim Roberts, Extension Specialist and Assistant Professor, Virginia Tech; Ruby Cox, Extension Specialist and Associate Professor, HNFE, Virginia Tech;
Publication Number 348-597, Posted February 1999
Food Preparation
Drying
Pasteurizing and Conditioning of Dried Foods
Storing the Food
Reconstituting Dried Foods
References
Heat - high enough to force out moisture but not hot enough to cook the food
Dry air - to absorb the released moisture
Air movement - to carry the moisture away
Natural drying, outdoors, requires warm days of 90 degrees F (32 degrees C) or more, low humidity, and control of insects. Oven drying or using a food dehydrator are alternatives for small quantities of food. The energy cost of operating an oven is high, however, compared to the cost of operating an electric food dehydrator.
Vegetables may be steam or water blanched as follows.
Steps for steam blanching
Steps for water blanching
Dipping is an alternative to blanching used to prevent fruits such as apples, bananas, peaches, and pears from turning brown. Lemon juice, ascorbic acid, or commercial products containing ascorbic or citric acid may be used for dipping. For instance, dipping sliced fruit pieces in 1 teaspoon of ascorbic acid crystals per cup of water or directly in lemon juice for three to five minutes will prevent browning.
* Dried vegetables should be brittle or crisp.
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NOTE: Sun drying is not recommended in cloudy or humid weather. The temperature should reach 90 degrees F by noon and the humidity should be less than 60 percent.
Oven Drying
* Fruits may be dipped in ascorbic acid or citric acid in place of blanching.
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Dried fruits must be conditioned prior to storage. Conditioning is the process of evenly distributing moisture present in the dried fruit to prevent mold growth. Condition dried fruit by placing in a plastic or glass container, sealing and storing for 7 to 10 days. The dried fruit in the containers should be shaken daily to distribute moisture. If condensation occurs, place the fruit in the oven or dehydrator for more drying and repeat the conditioning process.
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Dried foods should be used within 3 to 6 months as they will lose their flavor and color to some extent during storage.
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Food Preservation in Alabama, Alabama Cooperative Extension Service, Auburn University, 1995.
For additional information on drying fruits and vegetables, contact the
local Virginia Cooperative Extension office in your area.
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Food Preparation
You need 3 things for successful home food drying:
Fruit Vegetable
Apples Snap Beans
Apricots Beets
Bananas Carrots
Cherries Sweet Corn
Citrus Peel Garlic
Coconuts Horseradish
Figs Mushrooms
Grapes Okra
Nectarines Onions
Peaches Parsley
Pears Peas
Pineapples Hot and Sweet Peppers
Plums Irish Potatoes
Rhubarb Pumpkin
Tomatoes
Vegetable
Blanching Time
Drying Time*
Method
Minutes
Method
Hours
Broccoli Steam 3 -- 3-1/2 Sun 8 -- 10
Water 2 Oven 3 -- 4-1/2
Snap Beans Steam 2 -- 2-1/2 Sun 8
Water 2 Oven 3 -- 6
Beets Cook before drying Sun 8 -- 10
Oven 3-1/2 -- 5
Carrots Steam 3 -- 3-1/2 Sun 8 Water 3-1/2 Oven 3-1/2 -- 5
Onions Not necessary Sun 8 -- 11
Oven 3 -- 6
Peppers Not necessary Sun 6 -- 8
Oven 2-1/2 -- 5
Summer Squash Steam 2-1/2 -- 3 Sun 6--8
Water 1-1/2 Oven 4 -- 6
Winter Squash Steam 21/2 - 3 Sun 6 - 8
Water 1 Oven 4 -- 5
Tomatoes Steam 3 Sun 8 -- 10
Drying
Natural Sun Drying
Fruit
Blanching Time*
Drying Time**
Method
Minutes
Method***
Hours
Apple Steam 5 Sun 36 -- 48
Oven 6 -- 12
Apricots Steam 3 -- 4 Sun 24 -- 36
Water 4 -- 5 Oven 24 -- 36+
Figs Not necessary Sun 48 -- 60
Oven 12 -- 20
Grapes: seedless Not necessary Sun 36 -- 60
Oven 12 -- 20
Peaches Steam 8 Sun 36 -- 60
Water 8 Oven 36 -- 48+
Pears Steam 6 Sun 60
Water 8 Oven 24 -- 36+
** Test for dryness by cutting the fruit. There should be no moist areas in the center of the fruit.
*** A food dehydrator could be used in place of a range oven due to the extended drying times for most fruits.
+ Drying times for whole fruits. Drying time may be shortened by cutting fruit into slices.
Fresh Fruits Dehydrated apples, 20 lbs. 2 lbs. peaches, 20 lbs. 1-1/2 - 2-1/2 lbs. pears, 20 lbs 2-1/4 lbs. prunes/plums, 20 lbs. 2-1/4 lbs. Fresh Vegetables Dehydrated snap beans, 20 lbs. 1-3/4 lbs. beets, 20 lbs 2 lbs. carrots, 20 lbs. 1-3/4 lbs. onions, 20 lbs. 2-1/2 lbs. squash (summer), 20 lbs. 1-1/2 - 2 lbs. tomatoes, 20 lbs. 3/4 lbs.
Pasteurizing and Conditioning of Dried Foods
All sun-dried fruits and vegetables must be pasteurized to destroy insects. Place dried food evenly in shallow trays no more than 1 inch in depth. Vegetables should be heated at 150 degrees F for 30 minutes or
160 degrees F for 10 minutes. Fruits should be heated at 160 degrees F for 15 minutes.
Storing the Food
Cool dried food should be placed in a closed container that has been washed and dried before storing. Home canning jars are good containers for storing dried foods. Store in a cool, dry, dark place.
Reconstituting Dried Foods
Dried fruits and vegetables may be reconstituted (restoring moisture) by soaking the food in water. Time for reconstituting will depend on the size and shape of the food and the food itself. Generally most dried fruits can be reconstituted within 8 hours, whereas most dried vegetables take 2 hours to be reconstituted. To prevent growth of microorganisms, dried fruits and vegetables should be reconstituted in the refrigerator. One cup of dried fruit will yield approximately 11/2 cups of reconstituted fruit. One cup of dried vegetable will yield approximately 2 cups of reconstituted vegetable. Reconstituted fruits and vegetables should be cooked in the water in which they were soaking.
References
Complete Guide To Home Canning, Extension Service, USDA, 1994.