Study of rehydration of osmotically pretreated dried fruit samples

Hydration properties of osmotically pretreated apple samples were studied during storage in a humid environment. Hydration kinetics was measured and the effective water diffusivity was estimated. The hydration kinetics showed that there was a gradual water uptake to a maximum moisture content significantly lower than the expected equilibrium moisture content. Products that absorbed a high quantity of moisture during rehydration seemed to lose water. The explanation for the decreasing moisture content, after a certain moisture uptake, was related to the crystallization of amorphous sugars. The diffusion coefficient of water during rehydration of dried apple samples depends strongly on the osmotic treatment.