Drying or dehydrating food involves removing its water content to a point where the food is preserved for a longer time than if left fresh. The lack of water prevents microorganisms, such as mold, from decomposing the food. Food enzymes, which are naturally occurring proteins involved in the growth of a plant, also slow down when food is dried and help lengthen the food’s shelf life.
Drying of foods occurs best around 140°F. At higher temperatures, foods tend to cook rather than dry. Dried fruits should reach 20% moisture and be pliable, but not sticky. Dried vegetables will be brittle or crisp, with a moisture level of 10%.
Drying Methods
Electric Food Dehydrators
Food dehydrators are an electric appliance. Both horizontal and vertical dehydrators are effective and hold racks or trays of food to be dried. With a fan, warm air blows through and around the food, helping to remove moisture.
Oven and Microwave Drying
Drying using an oven or microwave is best for households that only want to dry occasionally and in small batches. When using an oven to dry, make sure the oven can maintain a low temperature of 140°F. If so, proceed with drying. Keep the oven door open slightly and have a fan blowing toward the oven to create a environment similar to an electric food dehydrator. Microwave drying is only recommended for herbs.
Sun, Solar, and Vine Drying
Sun, solar, and vine drying are not recommended methods for preserving food in Illinois since the weather, temperatures, and humidity make ideal drying conditions hard to maintain. In areas that can meet ideal conditions, sun drying is acceptable for fruits but not for vegetables or meats.
- Sundried foods also require pasteurization to destroy insects or eggs that may be present.
- Solar drying uses a foil surface to increase the temperature where the food is being dried and shortens drying times.
- Vine drying is used for legumes and other dry beans. Simply leave the vine alone to let the pods dry and shrivel before harvesting.
Air Drying
This indoor drying method works well for hot peppers and herbs. Create a bundle of hot peppers or herbs. Tie them together with string, and leave the bundles in a well-ventilated area until the food dries completely. Consider covering the food bundles with a paper bag poked with holes to prevent dust from gathering on the food’s surface. Drying outside can lead to a loss of flavor and color.
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Drying Fruits
Dried fruits are full of flavor, make tasty snacks, and can be added to a wide variety of dishes, including salads, meat dishes, and hot or cooked cereals. Rehydrated dried fruits make delicious baked goods such as cobblers, pies, puddings, and breads.
Pre-treatment
Treating fruits before drying improves colors and quality. For fruits that brown when exposed to air, use vitamin C (Ascorbic acid), citric acid, or lemon juice. For small fruits with skins or pits, pre-treat by blanching. Choose a pre-treatment method based on the type of fruit you plan to dry.
Pre-treatment Options
For Fruits that Brown
| Pre-treatment | Amount | Action |
|---|---|---|
| Vitamin C (Ascorbic acid) | 2-½ Tablespoons per 1 quart cold water | Prepare pre-treatment mixture. Soak fruit for 10 minutes. Drain and add to dehydrator to begin drying |
| Citric acid | 1 teaspoon citric acid per 1 quart cold water | |
| Lemon juice | 1:1 parts lemon juice and cold water |
For Small Fruits and Fruits with Pits
| Pre-treatment | Amount | Action |
|---|---|---|
| Boiling | Enough water to hold the amount of fruit. | Bring a pot of water to a boil. Add fruit, and boil for 30 to 60 seconds. Remove to very cold water. Place fruit on clean cloth to dry, then add to dehydrator. |
Conditioning Fruit
After drying, fruits need an additional step called “conditioning”. Since some pieces of fruit may be larger or smaller and are at different spots in the dehydrator, moisture may vary through each piece of fruit.
- Let dried fruit cool.
- Pack loosely into food-safe jars or covered containers.
- Close the containers.
- Let stand at room temperature for 7 to 10 days.
- Check the container daily for any condensation or moisture. If condensation is visible, add the fruit back to the dehydrator until dry.
Conditioning Instructions
- Let dried fruit cool.
- Pack loosely into food-safe jars or covered containers.
- Close the containers.
- Let stand at room temperature for 7 to 10 days.
- Check the container daily for any condensation or moisture. If condensation is visible, add the fruit back to the dehydrator until dry.
Need More Details?
For full instructions on preserving food by drying, visit the National Center for Home Food Preservation.