Evaluation of storage stability of dried cranberry powders based on the moisture sorption isotherms and glass transition temperatures

Abstract

The aim of this study was to evaluate the storage stability of dried cranberry powders based on the moisture sorption isotherms and glass transition temperature (T g). Microwave-vacuum dried (MWVD) and hot air convective dried (HACD) cranberry powders were kept at storage temperatures (T S) of 10, 20, 30 °C. Based on the coefficient of determination (R 2 > 0.99) and percentage global relative square error (1.2 < GRSE < 3.7%) of the approximation it can be stated that Guggenheim–Anderson–de Boer (GAB), Lewicki and Peleg models well described the relationship between water activity (a w) and the equilibrium moisture content (EMC) of dried material. Storage temperature and drying method did not significantly influence the sorption isotherms of cranberry powders. The variations in T g vs. a w and T g vs. EMC were adequately predicted by Khalloufi, linear (R 2 > 0.98; 1.8 < GRSE < 13.7%), square and Gordon–Tylor (R 2 > 0.89; 18.0 < GRSE < 34.6%) models, respectively. The optimum a w, EMC and T S for storage of MWVD and HACD cranberry powders were 0.30, 0.056 g H2O·g−1 DM, ≤ -2.6 °C, and 0.30, 0.055 g H2O·g−1 DM and ≤ -0.7 °C, respectively.