As shown on our DVD, a cooler is used as an incubator to provide a warm and moist environment. All you need is a small aquarium heater and a small aquarium air pump ( see "Notes"). It takes about 5 gall of water. The water should be emptied after two batches have been made in succession to prevent the growth of unwanted organisms.
Any cooler will work as long as you make the air bubbler tube from 1/2 PVC pieces.
More energy efficient coolers are the so called “ 5 day or 6 day” coolers because they have more insulation and will therefore show less condensation on the inside from the moist warm air during the incubation process. Both Coleman and Igloo carry them.
Make sure the tray you want to work with fits into a cooler comfortably. For the small cooler, the 10”x15” tray was just the right size and it was supported on 4 6” tall glasses; the water level needs to be 2 mm higher. This setup makes just over 2 lb. or 15 patties.
For a larger cooler and about 3 lb. of finished tempeh (18 patties), the food industry’s full size pans (also called 1/1; approx. 20” x 12”) are very useful. These pans will float and need no support. They are available in stainless steel and high temperature poly carbonate and both work fine; they also come with lids, which is helpful when putting them in the oven for pasteurizing after incubation. The full size pan we used has a depth of 2.5”. For this set up you need to use at least 8 gallons of water in the cooler to avoid overheating.
If you are making the tempeh in a cool area you might get condensation on the underside of the lid which could drop down on the tempeh.
To avoid this, make a spacer from 1/2” PVC so the tempeh can still breathe and stay dry.