Drying removes the moisture from the vegetables so that bacteria, yeasts and molds cannot grow and spoil the vegetables. It also slows down the action of enzymes, but does not inactivate them. Because drying removes moisture, the vegetable becomes smaller and lighter in weight. The optimum temperature for drying vegetables is 140° F. If higher temperatures are used the vegetables may "case harden", that is cook and harden on the outside while trapping moisture on the inside. The vegetables will eventually mold when the moisture equilibrates in the item. Thus, the drying process should never be hurried by raising the drying temperature.
For vegetables, drying time is critical to tenderness. The longer the drying time, the less flavorful and poorer the product. Drying time can be hastened by drying small, uniformly cut pieces.