Wash the apples in cold water with a squirt of dish soap and vinegar. Soak them briefly to remove grime and pesticide residues, then rinse and dry.
Peeling the apples is optional (much of the nutrition in apples is close to the peel). Core the apples and cut them into 1/4-inch slices.
Soak the slices in ascorbic acid solution for 1 minute, the drain them.
Arrange the slices in a single layer on the dehydrator trays.
To Dehydrate
Dehydrate at 135F for 4 hours. Reduce the temperature to 125F and continue drying for 4 to 8 hours.
When dried, the apples should be leathery and crisp, with no spongy areas in the middle.
Condition the apples before storing.
To Store
Wrap the slices in a paper towel before sealing in a Mylar bag, to prevent them from piercing the bag in storage. Dried apples stored in vacuum-sealed glass jars, or Mylar bags with oxygen absorbers, will keep for up to 5 years.
Notes
For the best flavor, choose fully ripe, firm, unblemished apples, with tight skin. Firm apples like Golden Delicious, Gala, Fuji, and Honeycrisp are the best for dehydrating, although you can use any kind of apple you have on hand.
To learn to make apple pectin from these dehydrated apples, please see the post.