Select mature, firm apples, picked at the peak of the apple season. Wash well. Peel, core and slice 1/8 to 1/4 thick. Arrange in a single layer on trays. Dry at 135F for 6 to 24 hours. Drying times depend on initial moisture content of the product. The dryness of our typical high desert weather speeds the process! The apples are done when the surface is dry and the center is no longer moist, but the slices will remain soft and pliable. To test for dryness, remove a few pieces and let cool to room temperature. Squeeze with your fingers. If no moisture is left on the hand and pieces spring back when released, they are dry.
When drying is complete, some pieces will be moister than others due to their size and placement during drying. To evenly distribute the residual moisture throughout all pieces, place cooled, dried fruit loosely in large plastic or glass containers, about two-thirds full. Lightly cover and store at room temperature, in a dry, well-ventilated place for 4 to 10 days. Stir or shake containers daily to separate pieces. If beads of moisture form inside, return food to drying trays for further drying, then repeat this step. When done, pack dried apple slices in small amounts in clean and dry glass jars (preferably dark) or in moisture and vapor proof freezer containers, boxes or bags. Label and date packages. Store in a cool, dry, dark place. Properly stored, dried apples keep well for six to 12 months. Discard foods that have off odors or show signs of mold. Read the Food Dehydrating article.