Solar Food Drying
The art of drying food using solar energy is a little more complicated than you might think. We have tried to gather some practical information and to provide links to other resources. Although dried food is popular with campers, backpackers etc. this page
is driven by the need for solar dryers in areas where fruit is plentiful in summer months, but because there is no simple and economic method to preserve it, much of it is left to rot, while in the winter there is hunger.
Solar food drying can be used in most areas but how quickly the food dries is affected by many variables, especially the amount of sunlight and relative humidity. There are some basic guidelines to drying food.
Most of the resources we researched recommend pre-treatment of the food, such as blanching, (boiling/steaming). Many experienced users do not pre-treat food.
Wash fresh fruits and ripe vegetables thoroughly.
Effective drying is accomplished with a combination of heat and air movement.
Remove 80 to 90% of moisture from the food.
Typical drying times range from 1 to 3 days, again depending on sun, air movement, humidity, and type of food.
Once the drying process has started it should not be interrupted, do not allow to freeze.
Direct sunlight is not recommended.
Temperature ranges of 100 to 160 degrees will effectively kill bacteria and inactivate enzymes, although temperatures around 110 degrees are recommended for solar dryers.
Too much heat especially early in the process will prevent complete drying.
Food should be cut into thin slices, less than 1/2″ thick and spread out on trays to allow free air movement.
Rotate trays 180 degrees daily for uniform drying. Move dryer food to bottom racks.
Safe tray materials include Stainless steel rack-wood slats-cheesecloth-Teflon -Teflon coated fiberglass-nylon -food grade plastics
Allow food to cool completely before storing.
Store food in air tight jars or plastic containers, and do not expose dried food to air, light or moisture.
Most fruits taste great dried including apples, apricots bananas, grapes etc.
Vegetables are best reconstituted by covering with cold water until they are near original size.
They can be added in their dry form to soups/stews. Vegetables can also be ground into powders and used for instant soups or flavoring.
Proceedings of Ises Solar World Congress
Budapest 1993, Volume 8.Numerous papers on
solar drying of various crops.
Basic Solar Dryer
Led by Associate Professor Greg Metha, Head of Chemistry, the researchers are exploring how the metal nanoparticles act as highly efficient catalysts in using solar radiation to split water into hydrogen and oxygen. “Efficient and direct production of hydrogen from solar radiation provides a renewable energy source that is the pinnacle of clean energy,” said Associate Professor Greg Metha. “We believe this work will contribute significantly to the global effort to convert solar energy into portable chemical energy.”
Inkjet printers, a low-cost technology that in recent decades has revolutionized home and small office printing, may soon offer similar benefits for the future of solar energy. Engineers at Oregon State University have discovered a way for the first time to create successful “CIGS” solar devices with inkjet printing, in work that reduces raw material waste by 90 percent and will significantly lower the cost of producing solar energy cells with some very promising compounds.