Moisture Sorption Isotherms of Lincheu Mushroom (Ganoderma lucidum)

Abstract

Sorption isotherms of lincheu mushroom (ganoderma lucidum), a medicinal herb were determined at three temperature levels of 30°C , 40°C and 50°C in the range of the relative humidity from 11% to 97% by using dynamic method. Ten two variable and five three variable isotherm models were selected to fit the observed data. Two variables models are good for the temperatures for which these models were derived while the three variable models are good for any temperature within the range for which it was derived. Among the two variable models the GAB equation was found to be the best to the experimental isotherm data of lincheu mushroom for the temperature levels of 30, 40 and 50°C and the temperature effect on the parameters was not consistent. Among the three variable models the Day and Nelson equation was found to be the best to the experimental isotherm data of lincheu mushroom for the temperature levels of 30, 40 and 50°C. The GAB model and Day and Nelson model were the most suitable models for estimating sorption isotherms of lincheu mushroom. The heats of sorption of water were determined from the equilibrium data using the Clausiaus-Clapeyron equation. The heat of sorption of lincheu mushroom decreases with an increase in moisture content and is found to an exponential function of moisture content. This equation can be used for computation of heat of sorption of lincheu mushroom.