Desorption isotherms and thermodynamic properties of sweet corn cultivars (<i>Zea mays</i> L.)

Abstract

Summary The desorption isotherms and thermodynamic properties of two cultivars of sweet corn were obtained during the drying process of these products. The isotherms were determined by a dynamic method for various temperature and humidity conditions. Equilibrium moisture content ( X eq ) data were correlated by the Guggenheim–Anderson–de Boer model and an artificial neural network (ANN) model. These models were fitted to the experimental data. The X eq for corn grain increased with an increase in the relative humidity at fixed temperature and decreased with an increase in temperature at a constant relative humidity. The experimental data were analysed by a thermodynamic approach to obtain the isosteric heat of desorption (Δ H ), differential entropy (Δ S ), activation energy ( E a ) and Gibbs free energy (Δ G ). The Δ H and Δ S increased with a decrease in moisture content, while Δ G decreased exponentially with an increase in X eq . The Arrhenius equation was used to obtain E a values, with Supersweet corn having higher E a .