酸奶制作时乳酸菌的分离纯化及最佳添加比例

Separation,Purification and Optimal Addition Ratio of Lactobacillus in Yogurt Production

[目的]研究酸奶制作时保加利亚乳杆菌和嗜热链球菌的分离纯化、发酵性能、添加比例。[方法]使用选择性培养基分离出保加利亚乳杆菌和嗜热链球菌,并对其发酵性能和传代特性进行测定,最终选择出发酵性能较好的保加利亚乳杆菌和嗜热链球菌;将分离出来的保加利亚乳杆菌和嗜热链球菌以不同比例在脱脂乳中进行混合菌株发酵,确定制作酸奶时两者的最佳添加比例。[结果]在酸奶发酵时,保加利亚乳杆菌和嗜热链球菌的添加比例为1∶1时,发酵脱脂乳粉可以在4 h内凝乳,发酵产品活菌数为5.4×10~7CFU/mL,酸度达到78.1°T,pH为4.50,发酵性能较好。[结论]该研究为乳酸菌在实际生产中更好的应用提供理论。

[Objective] The research aimed to study the separation,purification,fermentation performance and addition ratio of Lactobacillus bulgaricus and Streptococcus thermophilus when making yogurt. [Method]Lactobacillus bulgaricus and Streptococcus thermophilus were isolated by selective medium,and their fermentation performance and passaging characteristics were determined. Finally,Lactobacillus bulgaricus and Streptococcus thermophilus with good fermentation performance were selected. The isolated Lactobacillus bulgaricus and Streptococcus thermophilus were mixed fermented in skim milk in different ratios,and the optimum addition ratio of the two was determined.[Result]During the fermentation of yoghurt,when the ratio of Lactobacillus bulgaricus and Streptococcus thermophilus was 1∶ 1,the fermented skim milk powder could be curd within4 h,the viable cell count of the fermented product was 5. 4 × 10^7 CFU/mL,and the acidity reaches 78. 1 °T,pH was 4. 50,and the fermentation performance was better.[Conclusion]This study provides a theoretical basis for better application of Lactobacillus in actual production.