With Niuxin persimmon as the raw material,optimized vacuum drying and vacuum freeze-drying processes are used to prepare Niuxin persimmon powder,and the effects of different processes on the quality of fruit powder are compared.The results show that the optimal vacuum drying process is filling thickness of 6 mm,drying time of 12 h and drying temperature of 60 ℃,and the optimal vacuum freeze-drying process is filling thickness during pre-freezing stage of 15 mm,pre-freezing time of 4 h and pre-freezing temperature of-35 ℃.Gradient heating method is used in both sublimation drying and analytical drying.The quality of fruit powder prepared by the two processes is compared.The reducing sugar content(566.3 mg/100 g),total phenol content(13.24 g/kg)and total sugar content(731.6 mg/100 g)of vacuum freeze-dried fruit powder are all higher than those of vacuum dried fruit powder,but the total acid content(31.34 g/100 g)is lower than that of vacuum dried fruit powder.The color,taste and mouthfeel,solubility and water holding capacity of vacuum freeze-dried fruit powder are superior to those of vacuum dried fruit powder,but the fluidity is lower than that of vacuum dried fruit powder.The quality of Niuxin persimmon powder prepared by the optimized vacuum freeze-drying process is better than that processed by vacuum drying process.
维普
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