Sorption isotherms and drying kinetics modelling of convective and refractance window drying of feijoa slices (<i>Acca sellowiana</i> Berg)

Abstract

The refractance window and convective drying modelling of feijoa is important to dryers design used for the fruit preservation. This work presents the sorption isotherms and the drying kinetics of the convective and refractance window drying of feijoa slices. Feijoa was dried by convective drying at 50, 60, and 70°C, air velocities of 0.5 and 1 ms−1 and by refractance window at 60, 70, 80°C, with thicknesses of 3 mm and 5 mm for both technologies. The sorption isotherms were determined at 25, 35 and 45°C. Twelve thin-layer models and the effects of the operative conditions were analysed. The most suitable models were the logistic and Midilli for both drying methods. The Peleg adsorption model adequately described the experimental data over the entire measured range of the water activity. Drying modelling and sorption isotherms can be used in process optimisation and dryers design.