Yours truly enjoys growing tomatoes with kids in the neighborhood, meaning I usually have a cherry tomato plant, roma varieties, etc. Producing more fruits than I can reasonably eat, give away, etc.
What I have yet to pull off to add to my cooking repertoire is ... sun-dried tomatoes. Love 'em, cook with 'em, but don't love paying for them, but past attempts to dry the via non-electric means have mostly failed for reasons I attribute to Missouri's summer humidity. With growing season oncoming, I am wondering if y'all have any suggestions to get my excess tomatoes dried?
Also, if any of you have any flavoring tricks while the drying is going on, I'd love to experiment... is that a thing to do or no?
I also live in a humid area 90% is normal (97% right now) and I have not found any way to dry that is unpowered, we don't get much sun in the autumn so that means that trying to dry in a solar dehydrator or a car won't work. I've tried drying in the greenhouse as a larger and better ventilated version of the two previous methods but it doesn't work, they start to dry and then they go mouldy after about 4 days while still not being at all "dry".
I found the best method is a dehydrator with a heating element and a fan, but an oven set on it's lowest setting (50C) for my oven with the door cracked open and the fan on does the same job. For small amounts later in the year I can put them over the hot water tank on the furnace, but that's not in use in the summer. Whatever method I use I always finish them in the dehydrator/oven and then store straight away in airtight containers. leaving anything dried out for more than a few hours means it's not dried anymore!
Running a dehumidifier in the same room as the dehydrator/oven really helps reduce the time as well (not exactly a method avoiding electric though)
A car can work as a solar dryer. My tips to make it work most efficiently are to park it with the biggest window facing the equator and the windows down about an inch. Cover your screens of trays of food with a black or very dark cloth and it will help to generate heat while keeping sunlight off the food which would otherwise bleach out some of the nutrients.
As for tomatoes, you can give poor solar drying conditions a boost by how the tomatoes are prepped for drying. Start with small, less juicy tomato varieties. Black Cherry and Atomic Grape are a couple of our favorites for flavor. Cut the fruits in half and squeeze out the seedy, jelly-like interior (save for eating or drain and drink the juice). Then turn the tomatoes inside out and place skin side down on your trays. To further hasten drying along you can use your fingers to flatten out any thick areas of the fruits after they have started to form a dry surface, to break it up and expose the wet interiors. Another handy tool is a rolling mincer - it looks like several little pizza cutters side by side, about 1/4" apart. Running it across the fruits at 90 degree angles will help to speed up the drying process. These are my tricks for drying tomatoes in humid Minnesota and they work well in other areas of the midwest also.
I realize not everyone has this possibility but we live in an old house with a walk-up attic. There's a window at one end and we installed an attic fan at the other to keep the house cooler and preserve the roof and wood from the excessive heat. Even in our humid climate, the attic is the absolute best place for drying anything. I ran a clothesline on a pulley and we don't even own a clothes-dryer. In the summer, whoever does laundry wants to do it early in the day. I've dried elderberries up there as well as herbs. Haven't tried tomatoes yet but will give it a go this year. By autumn it's warm but not roasting so I cure our sweet potatoes and squashes up there. I even had success curing storage potatoes there.
Could you prepare them the way you like them and then freeze dry them? This process allows you to make thousands, freeze dry, bag 'em and they last for 15-25 years WITHOUT any flavor or nutrient changes!
The problem with the Appalachian or any dryer that emulates the stacked arrangement of trays like an electric dryer is that you're trying to move humidity-laden air through several layers of screens/food. Our dryer design, http://geopathfinder.com/Solar-Food-Drying.html works in a humid climate, or anywhere else for that matter, since the food is only one layer deep. This design has been in use by us since about 1985 and is easier to build than any other solar dryer I've come across and/or experimented with.
My wife and I have had this issue in Kansas, too. Even an electric dehydrator on low isn't fast enough to prevent mold in the really humid season. I think the issue in the Midwest is we don't cool off at night to drop enough dew out of the air so it starts muggy in the morning.
Best answer we have found is a small dehumidifier in a closet or other controlled airflow space. We are talking a less than $100 less than 100 watt unit. I know it is power, but not much and should be able to be sized for even a modest solar system.
We are definitely going to try Larissa's suggestions, they sound EXCELLENT.
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If you look at the 2 graphs on this page of our website webpage, you can see the data collected in an experiment with our design versus a couple of others. Yes, the humidity in the midwest is tropical. But our dryer design easily overcomes the humidity during the day. The humidity increase overnight is helpful when drying things like tomatoes as it allows you to come out the next morning and release the partially dried fruit from the trays and flip them or shift them around. Otherwise sticky foods have a tendency to "glue" themselves to the trays. This regained humidity is readily removed by the sun's energy on day 2, even if the weather is partially cloudy. Interestingly, this experiment shows that our dryer's temperature is below the ambient at night due to the physics of "black body radiation."
Running a dehumidifier on an off-grid solar system is no small load. I can't imagine our dehumidifier being able to accomplish anything close to what the solar dryer does all on its own power.
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