Food Drying Process
Sun or solar dried fruits and vine dried beans need treatment to kill any insect and their eggs that might be on the food. Unless destroyed, the insects will eat the dried food.
There are two recommended pasteurization methods:
1. Freezer Method – Seal the food in freezer-type plastic bags. Place the bags in a freezer set at 0°F or below and leave them at least 48 hours.
2. Oven Method – Place the food in a single layer on a tray or in a shallow pan. Place in an oven preheated to 160°F for 30 minutes. After either of these treatments the dried fruit is ready to be conditioned and stored.
Drying Foods Indoors
Most foods can be dried indoors using modern dehydrators, convection ovens or conventional ovens. Microwave ovens are recommended only for drying herbs, because there is no way to create airflow in them.
A food dehydrator is a small electrical appliance for drying food indoors. A food dehydrator has an electric element for heat and a fan and vents for air circulation. Dehydrators are efficiently designed to dry foods quickly at 140°F. Food dehydrators are a relatively new item and are available from department stores, mail-order catalogs, natural food stores, seed catalogs and garden supply stores. Costs vary from $40 to $350 or above depending on features. Some models are expandable and additional trays can be purchased later. Twelve square feet of drying space dries about a half-bushel of produce.
Everyone who has an oven has a dehydrator. By combining the factors of heat, low humidity and air flow, an oven can be used as a dehydrator. An oven is ideal for occasional drying of meat jerkies, fruit leathers, banana chips or for preserving excess produce like celery or mushrooms. Because the oven is needed for every day cooking, it may not be satisfactory for preserving abundant garden produce. Oven drying is slower than dehydrators because it does not have a built-in fan for the air movement. (However, some convection ovens do have a fan). It takes about two times longer to dry food in an oven than it does in a dehydrator. Thus, the oven is not as efficient as a dehydrator and uses more energy
To Use Your Oven – First, check the dial and see if it can register as low as 140°F. If your oven does not go this low, then your food will cook instead of dry. Use a thermometer to check the temperature at the “warm” setting.
For air circulation, leave the oven door propped open two to six inches. Circulation can be improved by placing a fan outside the oven near the door. CAUTION: This is not a safe practice for a home with small children. Because the door is left open, the temperature will vary. An oven thermometer placed near the food gives an accurate reading. Adjust the temperature dial to achieve the needed 140°F. Drying trays should be narrow enough to clear the sides of the oven and should be 3 to 4 inches shorter than the oven from front to back. Cake cooling racks placed on top of cookie sheets work well for some foods. The oven racks, holding the trays, should be two to three inches apart for air circulation.