Growing Appetite for Solar Energy in Food Processing


Open-sun drying has long been used to preserve many fruits, vegetables, and fish. The reason is simple: dehydrated foods stay fresher, longer on market shelves and at home. This is why you can purchase some fruits “off season.” What’s more, dehydrated products weigh less and are more compact, making them easier to store and ship across long distances. Solar food processing hopes to change the way food is dehydrated, adding cost efficiencies to the entire process.

Ideal for Rural Settings

Solar food processing provides high quality foods while minimizing today’s rising fuel costs. Many solar dryers, collectors and concentrators are already being employed in various areas of food processing and in adding value to foods. The basic design of solar food dryers as well as their handling ease has made products like the SEED Solar Dryer an ideal choice for food processing, especially in rural areas. By drying food close to where it’s harvested, the need for expensive transportation or storage of fresh produce is significantly reduced.

Conventional Drying Alters Food—Chemically and Physically

Conventional methods of drying fruits, vegetable and fish can change their physical and chemical properties—including altered color, texture, flavor and loss of nutrients. This is most often caused by the high temperatures conventional drying methods employ. One can lower the temperature but with that comes longer dehydration times and subsequent increases in overall product cost. Considering the fact that fresh fruits and vegetables are made up of nearly 80% moisture, dehydrating them to a moisture content of just 10% can take a considerable amount of energy. In some cases, dehydrating fresh produce can consume nearly one third of total processing costs.

The Many Factors of Solar Drying

Solar food drying employs a variety of processing steps. The product must first be pre-treated and spread out properly to allow free air circulation. Hot air must be efficiently circulated to draw out the product’s moisture. And drying times must be controlled by factors that include the initial moisture content vs. the product’s final moisture content. While freezing fresh food may be seen as a convenient way to preserve food, this method needs a steady, uninterrupted source of electricity. That means any foods so preserved will be vulnerable to power failures. Consider, too, the problems associated with freezer burn, which can limit the storage life of most frozen foods to approximately six months.

Uniting Two Emerging Technologies

Solar food processing combines two two emerging technologies to help address two critically important world problems: generate the energy needed for an ever-expanding world population and feeding the people in it. These problems are most acute in today’s developing countries where growing populations and lack of funds have left many rural areas far behind and undernourished. These far-flung regions often lack the reliable and affordable energy sources needed to properly store and transport fresh fruits, vegetable and fish.  Solar food processing efficiently addresses this disparity. It provides faster, cheaper and safer ways to both conserve and distribute food to many poor, typically rural peoples. Women and children are must vulnerable to the lack of availability of healthy foods.  Some statistics note that as much as 40% of food goes to waste in countries like India every year. The reason for this is that foods don’t survive post-harvest processing and preservation.

Small Scale Solutions

To provide underserved far-flung rural locales with nutritious fruits, vegetables and fish, solar food processing can begin in these areas on a small scale. With current available technologies, small solar food processing systems can concentrate solar energy for immediate and local use. Simple homemade solar food dryers use a clear glass top on a wooden dehydrator box. The heat trapped in the box dries the food, aided in some cases by an absorber plate inside, which indirectly heats the food via convection that enters through a vent at the bottom. As the food dries, hot air evaporates the moisture.

Posted on Wednesday, September 21st, 2016