jeremiah bailey wrote:
For sun dried tomatoes, there is a variety cultivated just for this purpose in Italy and available here in several seed catalogues. Principe Borghese, is a small, low water type tomato that has a flavor that is apparently improved by sun drying. It is a determinate plant, so the crop yields in a short window. They also hold very well on the vine, as long as it is still attached to the root system. When most of the fruit has ripened, simply cut the entire plant at the base of the vine and hang in the sun. The plant acts as a moisture extractor. Since it is no longer in contact with ground water via the roots, the water stored in the fruits reverses flow and exits back through the stems and leaves of the still attached plant. Pick the fruits once dry. I grew this variety last year, but only learned of the drying technique too late in the season. I did save the seed, but I'm not 100% sure of the purity of the strain as I didn't bag flowers and grew several other varieties nearby. I bought my seed from Territorial Seed Co., but other vendors sell it as well. I imagine this drying technique would work with other fruits as well.
paul wheaton wrote:
Nobody has answered. With zero knowledge, I'm gonna take a stab.
I think that that the sun will help to sterilize the food.
Emerson White wrote:
A bit nitpicky perhaps, but sterilize is not the word you want here, to sterilize is to kill everything living, and that would be very difficult to do with the sun, unless you were to get much much closer.
Emerson White wrote:
There is no such thing as partially sterile, so unless you do sterilize then nothing can have helped sterilize. Do you understand what I'm saying?
We have experimented with about every solar dryer design out there in the past 35 years and came up with our own design back in the mid-1980's that is actually pretty similar to the original posting. But it uses clear glazing and either black cloth or metal over the screen of food. And the roofing is at an angle to improve thermo-syphoning of airflow.
You can see the details on our webite at http://www.GeoPathfinder.com/9473 . That page gets about 150 hits/day, and we do workshops on the design, self-published a booklet about food drying, and do dryer building workshops with groups of folks in our area where we build 10, 4-by-4 foot dryers in a day. Our design was used by the U.N. in a publication they did back in the late '80's since it works well in humid regions, can be modified easily to adapt it to any climate, altitude, or latitude, and it's easy to use found or local materials as long as you stick to the basic physics of the design. It's now used from Alaska to Mexico, at least.
The box-type dryers are all based on adding a solar crutch to an electric box dryer. They work but you have to track the sun, they're slow, they're harder to build, and you can't leave food in them overnight.
We try to keep the direct UV of sunlight off everything but mushrooms. Some varieties, like shiitake, can have 10 times or more their normal vitamin D level if dries gill side up in direct sun. Fruits and veggies all get done in the dark to preserve nutrients and color.
Does anyone here know what material window screen is made from? Aluminum? Stainless steel? Galvanized steel? I've always wanted to make the simplest version possible of this dryer for mushroom drying (just a frame-mounted screen), but I've always beem concerned about aluminum or something toxic like zinc being absorbed by the mushrooms while drying. Is there any info on this?
Stainless is the safest kind of screen but costs more. I would think if you can get steel with no coating it would be ok. rub a bit of oil on it before use.
Mark Vander Meer wrote:This is a food dehydrator that works even in winter in Missoula