A solar dehydrator collects energy from the sun to heat air, which in turn, is used to dehydrate food and agricultural products. Dehydrated foods have a low moisture content, which helps to make them shelf stable and lightweight. Nutritional properties and health benefits of dehydrated foods are mostly retained compared to fresh. Dehydrated foods span a broad range of products from fruits to vegetables to nuts and meats. Popular dehydrated foods include beef, grapes, apples, prunes, peanuts, coffee and carrots. Dehydrated agricultural products include wood, flowers, hay, plants and insects. The objective of this fact sheet is to provide construction plans for a large-scale, home-use, solar dehydrator for foods and agricultural products.
The solar dehydrator construction plans are intended to serve as a guideline for construction, rather than as a rigid instruction set. Available materials, intended use, capacity, skills of the builder and other factors should be considered in plan implementation. For example, the dehydrator could be set on wheels to facilitate movement to sun-exposed areas, metal or fiberglass might be sub- stituted for some or all of the wood structure, and size of the dehydrator may be increased or decreased.
Some photos of the dehydrator under construction and after completion are provided in the construction plans to help the builder to visualize the process. Page 6 of the construction plans describes how the solar collector should be angled to face the sun to capture the most rays. An example angle (measured from vertical) of 77 degrees is shown. Online solar angle calculators are available to compute the angle, based on the site location and the time(s) of year the dehydrator may be used. A solar angle calculator may be found at http://solarelectricityhandbook.com/solar-angle-calculator.html. The optimum angle for a solar collector used primarily in the spring and fall at Stillwater, Oklahoma, is 54 degrees (measured counterclockwise from the 6 o’clock, or vertical, position).
The builder should consider personal safety while constructing the dehydrator. Follow safety instructions and good manufacturing practices for the tools and materials selected. Organize tools, supplies and instruc- tions to decrease opportunities for mistakes. Secure and protect the job site to prevent accidents from trip and slip hazards, trash and debris, electrical cords and unexpected visitors.
Food safety is a top priority for dehydration of edible materials. Dehydration naturally protects food products but will not inactivate all bacteria, spores, eggs, toxins or chemicals. Cleaning and maintaining clean food products is the best means to producing high-quality, safe, dehydrated foods. Wash and sanitize foods prior to preparation for dehydration. Wash hands thoroughly prior to handling food and frequently during processing. Clean and sanitize all utensils and food contact surfaces prior to use. Keep food products covered and protected from flies and other insects at all times. Store dehydrated foods in airtight containers in a cool place that is not exposed to the sun.
FAPC Food Process Engineer