A food dehydrator is a small electrical appliance for drying foods indoors. A food dehydrator has an electric element for heat and a fan and vents for air circulation. Dehydrators are efficiently designed to dry foods fast at 140ºF.
Food dehydrators are available at online shopping sites, department stores, natural food stores, and seed or garden supply catalogs.
Costs vary depending on features. Some models are expandable and additional trays can be purchased later. Twelve square feet of drying space dries about a half-bushel of produce. The major disadvantage of a dehydrator is its limited capacity.
Dehydrator Features to Look For
Double wall construction of metal or high grade plastic. Wood is not recommended, because it is a fire hazard and is difficult to clean.
Enclosed heating elements.
Counter top design.
An enclosed thermostat from 85ºF to 160ºF.
Fan or blower.
Four to 10 open mesh trays made of sturdy, lightweight plastic for easy washing.
UL seal of approval.
A one-year guarantee.
A dial for regulating temperature.
A timer. Often the completed drying time may occur during the night and a timer could turn the dehydrator off and prevent scorching.
Types of Dehydrators
There are two basic designs for dehydrators. One has horizontal air flow and the other has vertical air flow. In the units with horizontal flow, the heating element and fan are located on the side of the unit. The major advantages of horizontal flow are that it reduces flavor mixture so several different foods can be dried at one time, all trays receive equal heat penetration, and juices or liquids do not drip down into the heating element. Vertical air flow dehydrators have the heating element and fan located at the base. If different foods are dried, flavors can mix and liquids can drip into the heating element.
Excerpt from the National Center for Home Food Preparation - Food Dehydrators