Pasteurization of substrate for growing Pleurotus ostreatus by selfheating

Substrate to grow Pleurotus ostreatus must be pasteurized in order to be used for commercial production of Oyster mushrooms. The pasteurizing treatment normally involves steam application during a variable time/temperature procedure. In this research we studied an alternative treatment by forming a substrate compost pile with sufficient size and moisture to generate the necessary heat for pasteurization. A 1 m3 wooden box with 80 kg dry Pangola grass Digitaria decumbens + 2% lime (Ca(OH)2) was adjusted to 55, 60, 65 and 70% moisture. The composting treatment lasted 48 h; subsequently the substrate was cooled to ambient temperature and spawned. The treatment was efficient in preventing other organisms like flies, bacteria and competitor fungi. After two flushes of mushrooms, the biological efficiency was between 70.5 and 88.1% when compared to the control (same substrate steam pasteurized 90ºC, 1 h).