A few days back I set up a batch of tomato slices to dry in my tote-based solar food dehydrator. Without perfect weather, it was a race between sunlight and mold.
Mold won, as shown above.
At the minimum, this convinces me that I need an indirect solar dryer, as described in the just-prior post. My little plastic-tote dryer just doesn’t have enough power to dry tomatoes in less-than-perfect weather.
The interior of the tote seemed to get pretty hot, in full sunlight. As in 130F, loaded with just two small trays of tomato slices. So I’m not quite sure why this failed so badly.
One possibility is lack of direct ventilation of the tomato slices. I had a computer fan pulling air through this tote. While that did in fact exhaust the humid air in the tote, there was nothing blowing on the tomatoes to disrupt the “boundary layer” of air directly adjacent to each tomato slice. I would then guess that the air directly adjacent to each slice stayed quite humid, thus encouraging mold growth.
A second possibility is the lack of sterilizing UV radiation inside the tote. I believe the clear Sterilite tote is made of polyethylene, which is a reasonably good absorber of UV radiation. UV strongly inhibits mold growth, so the presence of warmth without UV was less than ideal.
Yet a third is the level of cloud cover. Depending on the day and the hour, the summer sky in Virginia can be quite cloudy. This power-ventilated box is going to cool off pretty rapidly in any extended period of cloud cover.
My bottom line is that if the weather is good enough to use this tote-based direct solar dehydrator, I’d be better off just sun-drying my tomatoes the traditional way. Lay them on a screen, cover them with netting, and expose them to the breeze and the sunlight.
Illustrations in this post are from Gencraft.com and Freepik AI. The only real picture is the first one, of blackened tomato slices sitting on drying trays.
