We concluded therefore that it was necessary to abandon the traditional incubation room concept. Tests had shown that circulating water was excellent for heat dissipation. The substrate is on a stainless steel tray. This tray sits on a support and is partially submerged in the waterbath. An insulated lid covers this tray and seals it from the environment.
Air is injected under the lid and drifts over the incubating tempeh to exit at the opposite end.
The temperature of the circulating waterbath is closely regulated for both heating and cooling. The utilization of stainless steel trays for this process was important since food-approved stainless steel is the standard in the commercial food business. Aluminum trays were not considered since the relation of aluminum to Alzheimer's disease is not clear at this time. Other metal trays are available which have a food-approved coating, but this would not stand up to daily use. Fiberglass trays with a food-approved coating would not hold up to the high temperatures reached during pasteurization.