Simulation of Intermittent Drying of Maitake Mushroom by a Simplified Model

Intermittent drying of Maitake mushroom (Grifola frondosa) was performed and simulated by a simplified plate drying model. The surface mass transfer coefficient H is a unique parameter for this model, capable of simulating every type of drying, including intermittent drying, simply and precisely. Moisture content during the tempering period is calculated using a similar method to that of the drying period except that the value of H is 0. There was a good agreement between the calculated and experimental values for the different tempering conditions. A tempering duration of about 20 min was recommended for intermittent drying of Maitake mushroom. The tempering temperature affected the refreshing effect: a higher tempering temperature yielded a higher refreshing effect. The effect of superficial air velocity υ on the surface mass transfer coefficient H was also determined. For thin layer drying at a constant air temperature and relative humidity H becomes constant if superficial air velocity is greater than the critical superficial air velocity υc.