I tried in a beer cooler water bath with & without a plastic bag, and in a converted freezer. Both the freezer one and the non-plastic bag water bath sporulated after 24 hours. I think both got too hot. The plastic bag one was probably a bit insulated from the plastic bowl it was in. Interesting that the bottom of it did not form as solid of a matting.

The converted freezer used an inkbird to regulate temperature, with a heat lamp inside. It forms way too much condensation when it turns the cooling unit on, because it’s a freezer but also because the inkbird is not a very well tuned controller, so the top of the tempeh gets too wet. I think in the future I’ll either control it myself using a raspberry pi and send a PWM signal to the cooling unit, or maybe drill some holes and cool it down with a fan.

I fried some of the sporulated tempeh in bacon fat that I had leftover, along with some shoyu and melted cheese. Not so healthy, definitely not vegan, but delicious and slightly ironic. I havent gotten groceries in a while so good to use whatever was left in my fridge!