Dehydration characteristics of the Oyster Pleurotus variety of mushroom were studied. Both untreated and treated (steam blanching followed by sulphiting and citric acid pretreatment before drying) mushrooms were dried in the thin layer drying experimental equipment at each of the drying air temperatures of 45, 50 and 60 degrees C with air velocities of 0.9 and 1.6 m/s. Studies on the equilibrium moisture content (EMC) of both untreated and treated dehydrated mushrooms were performed at different relative humidities ranging from 11.2 to 86.3% at 30 degrees C. In thin layer drying, mushrooms are dried under a constant-rate period for a short time at the beginning, and subsequently, they are dried under a falling-rate period for the rest of the time. Drying equations and EMC models for both untreated and treated mushrooms were developed. The quality characteristics of dehydrated mushrooms were analysed. Taking drying time and quality of the dehydrated product into account, a combination of a drying air temperature of 50 degrees C and an air velocity of 0.9 m/s appears to be suitable for drying of both untreated and treated mushrooms for a good dehydrated product. Copyright (C) 1996 Elsevier Science Ltd
