Moisture adsorption–desorption isotherms of Citrus reticulata leaves at three temperatures

The equilibrium moisture contents of Citrus reticulata leaves were measured by the gravimetric static method. The equilibrium was achieved after 12 days for desorption and 10 days for adsorption at 30, 40 and 50 °C with water activity ranging from 5% to 90%. The sorption isotherms of C. reticulata leaves decreased with increase in temperature at constant relative humidity. An hysteresis effect was observed. The experimental data of sorption were fitted by six models (Modified Henderson, Modified Chung-Pfost, Modified Oswin, Modified Halsey, GAB and Modified BET). Only the GAB and modified BET models were found to be the most suitable for describing the sorption curves. The net isosteric heat of sorption of C. reticulata leaves decreases with an increase in moisture content and was found to be a polynomial function of moisture content for adsorption and desorption.