Rehydration and sorption properties of osmotically pretreated freeze-dried strawberries

The aim of this work was to investigate the influence of osmotic dehydration and type of osmotic solution on selected physical properties of freeze-dried strawberries. Frozen Senga Sengana strawberries were dehydrated in osmotic solution with water activity of about 0.9 (sucrose and glucose solutions and starch syrup). Osmotically dehydrated fruits were frozen and freeze-dried at heating shelf temperature of 30 °C for 24 h.Rehydration, sorption isotherms and adsorption rate were determined for the freeze-dried strawberries. A decrease in rehydration capacity and adsorption rate was observed in the case of freeze-dried strawberries that were osmotically dehydrated in sucrose and glucose solution. Osmotic dehydration in glucose solution resulted in flatter sorption isotherms than osmotic dehydration in sucrose and starch syrup solution.