Moisture Sorption Behavior and Thermodynamic Properties of Gulabjamun Mix

Abstract

The equilibrium moisture contents of gulabjamun mix powder were determined at 10, 25 and 40C. The sorption isotherms of gulabjamun mix were of type II, with the sorption capacity decreasing with temperature. The Guggenheim–Anderson–de Boer best described the sorption data at all temperatures. The isosteric heat of sorption, sorption entropy, spreading pressure, net integral enthalpy and entropy were determined as a function of moisture content. The isosteric heat of sorption decreased with increasing moisture content, and it approached the latent heat of water at 15% moisture content. A plot of differential heat of sorption versus entropy satisfied the enthalpy–entropy compensation theory. The spreading pressures increased with increasing water activity but decreased with increasing temperature. The net integral enthalpy decreased with moisture content to a minimum value of −0.50 kJ/mol. The isokinetic temperature (Tβ) and harmonic mean temperature (Thm) values were determined as 339.5 and 297.5 K, respectively. Practical Applications The instant gulabjamun mix is a dry and convenient ready-to-use mix with long shelf life. In this study, the moisture sorption behavior and the thermodynamics of sorption of gulabjamun mix are presented. This work could be used as a reference to optimize the final moisture content of this product and specify its appropriate storage conditions. The sorption data will also be useful to predict the shelf life and stability of gulabjamun mix against deteriorative reactions.