Original article Desorption isotherms and thermodynamic properties of sweet corn cultivars (Zea mays L.)

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 (Xeq) 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 Xeq 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 (DH), differential entropy (DS), activation energy (Ea) and Gibbs free energy (DG). The DH and DS increased with a decrease in moisture content, while DG decreased exponentially with an increase in Xeq. The Arrhenius equation was used to obtain Ea values, with Supersweet corn having higher Ea.