Drying also slows down the action of enzymes, which cause food to ripen and eventually spoil. Because drying removes moisture, the food shrinks, and becomes lighter in weight. When the food is ready for use, water is added, and the food returns to its original shape. Certain foods can be dried in the sun, in an oven, or in a food dehydrator by using the right combination of warmth, low humidity and air currents. In drying, a warm temperature allows the moisture to evaporate.
Air currents speed up drying by moving the surrounding moist air away from the food.
Low humidity allows moisture to move from the food to the air. Drying food is a slow process. Sun drying takes three to five days while solar drying takes one or two days. It is difficult to do sundrying or solar drying in Minnesota because humidity is often too high. In a dehydrator, it will take 6 or more hours to dry foods, and in your oven, it will take 8 or more hours.