Effect of grape pretreatment on moisture isotherms

Moisture sorption isotherms are useful in predicting shelf-life stability and in calculating the variations of moisture content during drying, storage and packaging. In this study, the moisture sorption isotherms for pretreated seedless grape were determined using a static-gravimetric method at 40, 50, 60 and 70 C, and the effect of pretreatment solutions on the isotherms was investigated. In order to describe the sorption moisture isotherms, the BET, GAB and Halsey equations were tested to fit the experimental data by using non-linear regression analysis method. According to the modeling results, the GAB and Halsey equations gave the best fit for the samples. The net isosteric heat of desorption was calculated according to the obtained isotherms at different moisture content.