Effect of osmotic dehydration on desorption isotherms and glass transition temperatures of mango

The influence of different osmotic solution pretreatments (sucrose and glucose with concentration of 45%) on desorption isotherms and glass transition temperatures (T-g) of mango was investigated. The Peleg model satisfactorily described the relationship between water activity (a(w)) and moisture content of all samples (0.992 < r(2) <0.997). The equilibrium moisture content of mangoes osmotically pretreated in sucrose was higher than that of samples pretreated in glucose. Differential scanning calorimetry was used to measure the T-g of samples equilibrated with different a(w) (0.12-0.75). The dependence of T-g on moisture content was adequately fitted by Gordon-Taylor model (0.946 < r(2) <0.949). The osmo-dehydrated mangoes showed lower T-g than fresh samples at the same moisture content. Additionally, the samples osmotically pretreated in glucose showed the lowest T-g value.