Using your dehydrator is the easy part. Wash your produce, slice it, place it on the trays, and set the thermostat! Though the owner’s manual may recommend higher temperatures for faster drying, optimal temperature for preserving nutrients is about 115 to 120 degrees.
Drying time depends on a variety of factors, including the thermostat temperature (higher temperatures dry faster), the thickness of the produce (generally ¼ inch thickness is recommended, thicker pieces dry more slowly), the type of produce (the juicier the fruit, the longer the dehydration time), and even the humidity level in your house! Set at a high temperature, your dehydrator may scorch foods if they are left in too long. But set at the recommended low temperature, you can usually leave the food in for days without worrying about scorching or nutrient loss. (At low temperatures, longer is better, because it is better for stored food to be as dry as possible.) Simply place the food in, turn on the machine, and then check it in a day or two, and your food will probably be dry.
To determine if your food is done, touch it with your fingers. Does it feel dry? The type of food determines the texture it will exhibit when dried. Strawberries may be spongy, apples leathery, pears sticky, and herbs crumbly. Check the book that comes with your dehydrator for drying time and ideal texture for individual food types.