twelve hours. Preheat your oven and check that it can maintain a temperature of 130 to 145° for at least an hour—some ovens have a difficult time holding low temperatures like this, and going over 150° can be disastrous for drying produce. Wash and prepare the food, then spread food in single layers on baking sheets, making sure the pieces do not touch. Place the sheets directly on the oven racks, leaving at least 4" above and below for air circulation. Also, make sure to leave the oven door slightly ajar to allow moisture to escape. Rearrange the trays and shift food from time to time to ensure even drying.
You may also dry food on your oven’s range by creating a chafing dish. To create a chafing dish on your range, you’ll need two baking trays: The first must be large enough to cover all burners and hold a 3"-deep reservoir of water. The second tray should fit on top of the first. Fill the bottom tray with water and set all burners to low heat. Throughout the process, refill the reservoir periodically to make sure food doesn’t burn, and move/turn food as necessary to ensure even drying. Place a fan nearby to keep the air moving around the room, which will help carry moisture away from the food more quickly.
When drying produce in the oven, leave the door slightly ajar to allow moisture to escape, and carefully monitor temperature to ensure the oven doesn’t heat to over 150°.
An electric produce dehydrator can dry large quantities of fruits or vegetables in a sanitary environment. The stackable trays allow you to match the appliance’s drying capacity to your needs each time you use it.
How Long Does Dehydration Take?
Drying times vary considerably—from a few hours to many days, depending on the climate, humidity, drying method, and the moisture content of the food you’re dehydrating. Generally, fruit is done drying if it appears leathery and tough and no moisture can be squeezed from it. Vegetables should be so brittle and crisp that they rattle on the tray. To check for completed dehydration, you can also check the food’s weight before and after the process. If the food has lost half its weight, it is two-thirds dry, so you should continue to dry for half the time you’ve already dried.
To double-check that your food is dry, place it in a wide-rimmed, open-topped bowl covered with cheesecloth fastened with a rubber band. Place the bowl in a dry place, and keep the food in the bowl for about a week. Stir it a couple times a day—if any moisture or condensation appears, you should continue to dehydrate.
Enjoying Your Dehydrated Food
Many foods are delicious and ready to eat in their dried forms—especially tomatoes and berries. But dried food can also be rehydrated before eating. To rehydrate food, pour boiling water over it in a ratio of 1-1/2 cups of water to 1 cup of dried food, then let the food soak until all the water has been absorbed. You may also steam fruit or vegetables until rehydrated. Rehydrated vegetables should be cooked before eating, whereas rehydrated fruits are acceptable to eat without cooking after rehydration.
Pasteurization and Storage
Regardless of the drying method used, food should be pasteurized before storage to ensure that there are no insect eggs or spoilage microorganisms present. To pasteurize, preheat the oven to 175°. Spread dried food 1" deep on trays and bake in the oven for 10 to 15 minutes. Dried food is best stored in clean glass jars or plastic bags in a cool, dry place. Never store dried food in metal containers and carefully monitor the humidity of the storage environment. Containers should have tight-fitting lids and should be stored in a dark, dry place with an air temperature below 60°.
Use your oven to heat fruits and vegetables to a high enough temperature to kill bacteria and related contaminants. About 15 minutes at 175°F will suffice for most produce, provided it is not in layers over 1" deep. Oven-drying takes about a