o Total Drying or Dehydrating Area – How much space does the dehydrator have to dry food? The total dehydrating area is expressed in square feet and is calculated as follows: The product of a) the number of drying drays multiplied by the size of the drying trays (length by width in inches) divided by b) 144 square inches. As an example, if a dehydrator has 9 drying trays that are 15 inches by 15 inches each, then the total drying area equals 14.1 square feet (15 multiplied by 15 multiplied by 9 = 2,025, 2,025 divided by 144 equals 14.1). Obviously, the total dehydrating area determines how much food you can dry at one time. The total drying area should be adequate for the largest amount of food you will dry during a twenty-four hour period. As a rough rule of thumb, approximately one pound of food can be dried per square foot of drying area. However, this amount will vary depending on the type of food being dried, the thickness of the food slices and the food’s water content.
o Air Flow – Dehydrators remove moisture from food via heat and air flows. Food dehydrator air flows are designed either horizontally or vertically. Horizontal air flow food dehydrators have their heating element and fan located on one side of the dehydrator. The drying trays that hold the food are arranged like drawers inside the food dehydrator. Typically, horizontal air flow dehydrators are better at dehydrating different types of food at the same time as the horizontal air current mixes the food flavors less than vertical air flow dehydrators. Also, horizontal air flow dehydrators better prevent food juices from dripping down onto the heating element, thus making cleaning easier.