酸乳冻干产品的复水性研究

Study on re-hydration quality of freeze-dried yoghourt

将20g冻干酸乳与80g温水混合搅拌3～5min，与冻干前相比色泽无明显变化，外形类似鲜牛乳，不能恢复发酵酸乳的凝固状态。相比于新鲜发酵酸乳。黏度由100-125mPa·s下降至80—95mPa·s。气质串联色谱分析表明：酸乳冻干复水后风味物质种类、含量变化较小；感官实验表明，冻干复水酸乳的口感与新鲜制品极为相似。

After 20 g Freeze-dried yoghourts and 80 g water at room temperature were mixed round, the distinct change in color of freeze dried yoghourt did not occur compared to the fresh yoghourt. However, the semisolid state of yoghourt was replaced to liquid state which was very similar to fresh milk. Meanwhile, the viscous declined from 100-125 mPa.s to 80-95 mPa .s.The freeze-drying process affected survival of the lactic acid bacteria, resulting in a 2-3 log population reduction. After the analyses of volatile were performed using a Finnigan Trace GC-MS, the results showed that the distinct change in sorts and content of volatile did not occur compared to the fresh yoghourt. The sensory test showed that the flavor of rehydrated products was very similar to the fresh ones.