Carefully use a sharp knife or a mandolin to slice the apples into ¼ inch thick slices. As you slice the apples put the slices into the bowl of pretreatment solution. Repeat until all of the apples have been sliced and dipped.
Arrange the apple slices on prepared dehydrator trays.
Set the temperature to 135°F and let the magic happen for 6 to 8 hours. If your model doesn't have an adjustable temperature just turn the dehydrator on.