Using a microwave oven as a dehydrator is an effective way to dry and preserve low moisture foods, such as herbs, mushrooms and citrus peels. Commercial food dehydrators are available for this preservation method, but many American homes already contain handy microwave ovens. Dehydrating foods is an excellent way to save money when you run across bargains on produce and herbs. Dried foods take up little space and have a long shelf life.
Measure the inside of your microwave oven and cut a piece of cardboard to fit inside the appliance. If the microwave has a turntable, cut the cardboard to fit it.
Cover the cardboard with two layers of white paper towels.
Wash the herbs you want to dehydrate. Allow them to drain on paper towels and then blot them gently with a dry paper towel to remove excess moisture.
Place the herbs in a circle on the covered cardboard, leaving the centre empty. Put it into the microwave.
Set the microwave power to high and turn it on. Dehydrate 1 cup of herbs for approximately three or four minutes or until they are dry and brittle-looking. Twice that amount of herbs takes between five and six minutes, 3 cups dehydrate in approximately seven to eight minutes. Allow 10 to 11 minutes for 5 cups of herbs.
Crush the dehydrated herbs finely before storing them in an airtight container. Use about 1 tsp of dried herbs in a recipe that calls for 1 tbsp of fresh herbs.
Wash and dry the citrus fruit you wish to dehydrate. Leave the fruit whole to make it less difficult to grate. Rub the coloured section of the peel on the grater until you have 3/4 cup. Place it in a circle on the paper towels. Set the microwave at one-third power and turn it on for approximately 12 to 13 minutes. Rearrange the citrus peel halfway through the time. Use one-third of the amount of dried citrus peel to substitute for fresh citrus peel. Store the dried citrus peel in an airtight jar with a lid or another container. In areas with high humidity, microwave dehydration does not work well, because the food rapidly reabsorbs moisture from the air. Wash and dry your mushrooms before dehydrating them. Slice the mushrooms thinly until you have 1 cup. Place them in a circle in a single layer on the paper towels. Turn the power on high for approximately three to four minutes. Rotate the mushrooms. Set the microwave on one-third power and turn it on for another four to five minutes. Allow the mushrooms to cool before storing them in an airtight container.
Avoid using recycled paper towels in the microwave. They may contain bits of metal that can ignite when the power is on.