The art of food dehydration does not lend itself to iron-clad rules or specific times or temperatures. Much of what you do will be based on experimenting with different ways of preparing the fresh food or by varying times or temperatures. When something doesn’t work, evaluate the process you used to find out why. Many people like to keep a drying diary to refer to.
One of the most frequent problems is discoloration. Darkening, caused by enzyme action or oxidization, is a natural process that does not affect flavor. It occurs more easily in some produce than in others. Drying techniques also affect color.
Darkening may occur if:
Chemical dips are NOT necessary. Many books recommend that fruit or vegetables be dipped in solutions of sulfur, sodium bisulfite, or metabisulfite. This is not only unnecessary, but it has questionable health effects. If the above suggestions do not help, try dipping the fruit or vegetable in lemon juice, pineapple juice, or a solution of ascorbic acid (may be purchased at a health food store). These will help prevent oxidization, provide extra vitamin C, and add a pleasant flavor.