Dehydrated Peaches
Select fresh and fully ripened peaches. Immature peaches lack flavor and color. Drying does not improve food quality. Don’t dehydrate bruised and/or mushy peaches, the chips will become see-through, they will be to frail to even peel off the dehydrator tray. Use those peaches for raw peach ice creams or fruit leathers.

Pretreatment:

Treatment Option #1 ~ Ascorbic Acid Pretreatment (vitamin C)
Why: it is an antioxidant that keeps fruit from darkening and enhances destruction of bacteria during drying.
Where can I find this: Pure crystals usually are available at supermarkets and drug stores.
How do I use it: Stir 2 1/2 tablespoons (34 grams) of pure ascorbic acid crystals into one quart (1000 milliliters) of cold water. For smaller batches prepare a solution using 3 3/4 teaspoons (17 grams) of pure ascorbic acid crystals per 2 cups of cold water. Vitamin C tablets can be crushed and used (six 500 milligram tablets equal 1 teaspoon ascorbic acid). One quart of solution treats about 10 quarts of cut fruit. Soak the peach slices for 10 minutes, remove with a slotted spoon, drain well and dehydrate. (source)

Treatment Option #2 ~ Lemon Juice Pretreatment
Why: Lemon juice may also be used as anti darkening and antimicrobial pretreatment.
How do I use it: Mix equal parts of lemon juice and cold water (i.e., 1 cup lemon juice and 1 cup water). Allow the slices to soak 10 minutes, then remove with a slotted spoon, drain well and dehydrate.

Drying Tips:
Arrange the peaches on drying trays in single layers. Don’t over lap because they will stick together. The length of time needed to dry fruits will depend on the size of the pieces being dried, humidity, and the amount of air circulation in the dehydrator. Also keep in mind that thinner slices and smaller pieces will dry more quickly than larger ones. So I recommend slicing all the peaches the same thickness so that they dry evenly. Drying time can range from 6-36 hours at 115 (F)degrees.
Testing: Dry the peaches enough to prevent microbial growth and spoilage. You shouldn’t be able to squeeze any moisture out of the dried fruit. They should be leathery and pliable. To test the peaches for dryness, remove a few pieces and let cool to room temperature. When warm or hot, fruits seem more soft, moist and pliable than they actually will be once cooled. You can remove the peaches when they are more soft and chewy but keep in mind that the more moisture that is left in them, the shorter the shelf life.
Storing:
Pack cooled, dried peaches in small amounts in dry, scalded glass jars (preferably dark) or in moisture and vapor proof freezer containers or bags. Packaging warm dried peaches can cause moisture in the container which will create a breeding ground for mold. Package in small amounts. Every time a package is re-opened, the food is exposed to air and moisture that will lower the quality of the food.
Label packages with name of product, date and method of pretreatment and drying. Tightly seal containers to prevent re-absorption of moisture or entry of insects. Store in a cool, dry, dark place or in the refrigerator or freezer. Properly stored, dried fruits keep well for six to 12 months. Discard if they have off odors or show signs of mold.