Mass Transfer Kinetics of Osmotic Dehydration of Strawberries with Various Small-Molecule Sugars and Their Effect on the Quality of Freeze-Dried Strawberries

In order to systematically understand the osmotic dehydration behavior of strawberries with different small-molecule sugars, especially oligosaccharides and sugar alcohols, as well as their effect on the quality of freeze-dried strawberries, the osmotic dehydration kinetics of strawberries with 10 common small-molecule sugars (at a concentration of 40 °Brix) was fitted using two mathematical models and the physicochemical properties of freeze-dried strawberries obtained after osmotic dehydration were characterized. The results showed that the Weibull model was more suitable for describing the solid gain (SG) of osmotically dehydrated strawberries, while the Peleg model could better describe the water loss (WL). The SG of strawberries differed depending on the sugars used. More specifically, the SG of strawberries was 6.84 g/100 g after osmotic dehydration with sorbitol, which was 6.16 times higher than that with isomalt oligosaccharides. In addition, after osmotic dehydration, the hardness of strawberries was enhanced by 94.58% to 223.23%; the crispness of strawberries dehydrated with glucose, fructose and sorbitol was decreased by 16.70%, 20.74% and 41.45%, respectively. The texture characteristics of strawberries dehydrated with fructooligosaccharide were the closest to those with sucrose. Overall, considering the osmotic efficiency, sensory and nutritional quality and production cost, fructooligosaccharide seems to be a superior solute for osmotic dehydration of fruits and vegetables compared to sucrose.