Thermodynamic Analysis of Moisture Sorption Characteristics of Cheese-PuriMix

Abstract

Sorption data were determined by static gravimetric method for cheese–puri mix at 25, 35 and 45C. The Guggenheim-Anderson-deBoer (GAB), Caurie, Henderson, Oswin and Smith isotherm models were attempted to describe the experimental data and were found to describe the sorption behavior of the product adequately. The solid surface area of the product was computed based on the GAB model monolayer moisture contents of the product and was found to increase with temperature. Thermodynamic properties of the product, including the isosteric heat of sorption, sorption entropy, spreading pressure, net integral enthalpy and entropy, were determined as a function of the product moisture content. Application of the enthalpy–entropy compensation theory to the sorption data revealed that the process was enthalpy-driven. The net integral enthalpy and entropy were found to decrease with increasing moisture content and were described as a function of the equilibrium moisture content using a power model. Practical Applications Sorption isotherms are important tools for food scientists to understand the behavior of a food product, especially low-moisture foods, toward the moist air that envelopes its surroundings. They are particularly useful to predict the physical, chemical and microbial stability of the product during storage and reconstitution. Thermodynamic properties of the product provide an insight into the energy requirement associated with moisture sorption and the temperature dependence of water activity. Cheese–puri mix is a value-added convenience dairy product, and information on its sorption characteristics would be useful to monitor its quality and shelf stability.