复凝聚法鼠李糖乳杆菌微胶囊工艺优化及储藏稳定性

为提高鼠李糖乳杆菌在贮藏过程中的稳定性,以明胶、阿拉伯胶为壁材,采用复凝聚法制备鼠李糖乳杆菌微胶囊。研究以湿态微胶囊的包埋率为指标,考察pH、壁材浓度、转速和菌添加量对复凝聚法微胶囊制备的影响,在单因素试验的基础上进行正交试验,优化最佳工艺。将最优条件下的湿微胶囊进行喷雾干燥和真空冷冻干燥,并在不同水分活度和不同温度条件下研究了喷雾干燥和真空冷冻干燥鼠李糖乳杆菌微胶囊的储藏稳定性。结果表明,pH 3.75、壁材浓度1.5%、转速200 r/min、菌添加量109 CFU,此条件下制备的鼠李糖乳杆菌微胶囊包埋率最高,为93.21%;复凝聚法制备的鼠李糖乳杆菌湿微胶囊干燥后,每克真空冷冻干燥微胶囊的活菌数比喷雾干燥微胶囊高1.9个对数值;储藏时水分活度越低,温度越低,鼠李糖乳杆菌微胶囊的储藏性越好;与喷雾干燥微胶囊相比,储藏时真空冷冻干燥微胶囊在高水分活度下较稳定,且在不同水分活度、不同温度条件下的活性均高于喷雾干燥微胶囊。因此复凝聚法制备的鼠李糖乳杆菌微胶囊真空冷冻干燥后能更好的保护鼠李糖乳杆菌,延长其储藏期。

Optimization of the preparation technology of Lactobacillus rhamnosus GG microcapsules by complex coacervation and the storage stability

In order to improve the stability of Lactobacillus rhamnosus GG during storage,Lactobacillus rhamnosus GG was microcapsuled via complex coacervation with type B of gelatin and gum Arabic.The encapsulation efficiency of microcapsules was investigated under different processing conditions,including pH,the wall material concentration,stirring speed and number of viable bacteria added.The optimal conditions were obtained by orthogonal test based on single factor experiments using the embedding rate as the index.Meanwhile,this study also investigated the storage stability at different water activities and temperatures of Lactobacillus rhamnosus GG microcapsules using spray drying and vacuum freeze drying.The optimal conditions for preparing the microcapsules were pH=3.75;wall material concentration of 1.5%;stirring speed at 200 r/min;and the number of viable bacteria of 109 CFU.Under this optimal condition,the encapsulation efficiency was 93.21%.The viability of the microcapsules after vacuum freeze drying was 1.9 lg CFU/g higher than that of spray dried microcapsules.The storage stability studies demonstrated that the lower the water activity and the lower the temperature,the higher the cell survival.Considerably better survival was observed for vacuum freeze dried microcapsules compared to spray dried microcapsules at higher water activities,and the activity of vacuum freeze dried microcapsules was higher in any cases.The results indicated that vacuum freeze drying is an effective way to enhance storage stability for Lactobacillus rhamnosus GG microcapsules.