Water sorption enthalpy-entropy compensation based on isotherms of plum skin and pulp

The net isosteric heat and entropy of water sorption were calculated for pl um, based on sorption isotherms obtained by the static gravimetric method a t different temperatures (20 to 70 degrees C). The Guggenheim-Anderson-deBo er model was applied to the experimental data giving a good agreement betwe en experimental and calculated values. The net isosteric heat of water sorp tion, estimated by applying Claussius-Clapeyron equation to sorption isothe rms, was found to be different for plum skin and pulp, mainly at low moistu re contents, and could be well adjusted by an empirical exponential relatio nship. Plots of enthalpy in contrast to entropy provided the isokinetic tem peratures for skin and pulp, indicating an enthalpy-controlled sorption pro cess. Thermodynamic data on water sorption for plums are not found in liter ature, as opposed to prunes for which the data are abundant.