Stiebel Eltron
Stiebel Eltron Accelera 300 E Heat Pump Water Heater
The Stiebel Eltron Accelera 300 E Heat Pump Water Heater represents the pinnacle of water heating technology, engineered in Germany and leading the European ...
$2799
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How Does a Solar Dehydrator Work?
The system works by first having an intake at the bottom of the solar dehydrator. From here, the air draws into the collector box, where the sunlight passes through the clear glass or plastic cover and absorbs into a dark mesh screen. This screen transfers the absorbed heat to the surrounding air, which then naturally rises to the drying chamber on top. At this point, as the air moves up and out of the collector box through vents. Negative pressure is created at the base of the system, drawing more air and repeating the process. As the warm air reaches the drying chamber, it passes over the fruits, vegetables, and herbs, drawing moisture out of them as it moves through to the vent at the top of the section.
Over the years, the solar dehydrator has been experimented with and modified in various ways. The group found that the dehydrator resulted in higher drying temperatures by adding a double layer of glazing. Single glazed dehydrators still performed optimally, only operating with slightly reduced temperatures to the double glazed counterpart.
Scanlin and others also experimented with utilizing reflectors (aluminum foil, mirrors, reflective mylar) to gather additional solar energy into the system. By adding a vertical reflective wall on the drying chamber, they saw slight increases in the temperatures inside the system and even more from a single reflector mounted at the bottom. Side-mounted reflectors were also experimented with, showing a significant rise in temperature at the cost of needing more attention to adjust the solar dehydrator throughout the day. They concluded that single reflectors were the best option when adding additional solar power to your system.
On top of experimenting with gathering more sunlight, the group also delved into what made the best absorber within the dehydrator's collector chamber. They found that galvanized steel lath painted flat black produced a higher temperature in the drying chamber than the initially tested aluminum screen layers. However, steel lath can be harder to work with more expensive. The researchers also found that two to three layers of the screen or painted steel lath were more than enough for the dehydrator to work effectively. This discovery was contrary to their original design of five layers. Additional layers did add extra heat absorption, but at an increased cost.
Now, there are dehydrators for sale at various stores. But the majority of the products you will find for sale at retailers will be exclusively for powered dehydration and require an outlet. The price-point for a plug-in dehydrator will vary depending on the quality and functionality of the product. With standard dehydrators ranging from $60 to over $500, there are various options for every household. The DIY dehydrator is comparable to a higher-end product in material cost. They offer similar drying space and max temperature ratings. However, they are nowhere near as compact as the paid-for options.
Other options you will find available are drying racks which have their place for select herbs and vegetables.
Nutritional Value
One of the benefits of correctly dehydrating your foods comes from the retention of nutrients. When drying fruits and vegetables, you are removing water from the plant. This process leaves you with more concentrated carbohydrates, fats, and proteins per weight of fresh foods. Some vitamin loss does occur during dehydration, but this can be limited depending on your preparation methods and drying techniques.
Microorganisms
Microorganisms, like all living things, require moisture. Through dehydration, you remove the medium that these creatures thrive, reducing the likelihood that they grow to damage your food. While "microorganism" is a blanket term for microscopic organisms, we are referencing specifically bacteria, mold, and yeast in this discussion. By reducing moisture below 30%, you add an extra layer of protection to your food against the average bacteria or yeast. Molds, on the other hand, generally continue to be problematic down to 12% moisture content. You can take extra measures to either prepare or store your food after dehydration to get the most extended life out of your preserves.
Enzymes
Enzymes can lead to discoloration and the breakdown of plant tissue when damaged. This process can result in a loss of vitamins. Luckily most of these become inactivated at 158F and require moisture to enable activity. There can still be the chance of enzymes surviving the dehydrating process and affecting the final dried product. Extra steps recommended by Scanlin include blanching or sulfuring before drying to deactivate the enzymes.
Food Storage
Besides the benefits drying has for the health of your shelved produce, it benefits you by how much farther your summer harvest can go. Needing only a sunny day to dehydrate your crop, you can extend how long you enjoy the flavors of garden tomatoes or climbing beans for months to come. Using tiny garden methods, like Square Foot Gardening, you can plan out what crops to enjoy and what ones to store. Using this method, you are getting the best of both worlds by enjoying a flavourful treat now and saving some for a later date.
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