Moisture sorption studies on vacuum dried coconut presscake.

Moisture sorption isotherms of vacuum dried coconut presscake were determined at 25 °C, 30 °C, and 38 °C using a gravimetric technique. Sorption isotherms exhibited Type II behaviour. The effect of temperature on equilibrium moisture content was not significant (p > 0.05). Three models available in the literature viz., GAB, BET, and Halsey models were fitted to the sorption data. Out of the three tested models, Halsey model best fitted the experimental data with a relative deviation percent below 10%. The net isosteric heat of sorption was determined from the equilibrium adsorption data using the Clausius-Clapeyron equation. Isosteric heats of sorption were found to decrease exponentially with increasing moisture content.