影响乳酸菌冷冻干燥抗性因素的研究

研究了生长培养基、菌体收获菌龄、预培养条件、保护剂等因素对保加利亚乳杆菌(Lactobacillus bul- garicus)冷冻干燥存活率和活力的影响。确定了加有1%生长因子和1%CaCO_3的NFM培养基(10%的脱脂乳),可使保加利亚乳杆菌的对数生长期延长。菌体的最佳收获菌龄为4.5 h;保护剂组成为:3%NFM+3%乳糖+3%甘油;40℃预培养1 h,其存活率可达75.5%。具有较为理想的效果。此外,在优化的试验条件下研制的冻干酸奶发酵剂制备的酸奶,达到了预定的标准。

The Study on Factors upon Freeze-drying Livability of Lactobacillus bulgaricus

The paper studied on some factors that affect the frozen drying livability of Lactobacillus bul- garicus.The factors could be culture ingredients,the cell collecting time,the condition of preincubation, and the protective medium components.The results showed that the NFM culture with growth factor and 1%CaCO_3 is relative ideal.The selected culture can extend the Lactobacillus bulgaricus logarithmic phase and enhance the live cell number.The optimal cell collecting time was 4.5 hour.The strain was respectively preincubated for 1,2 and 3 hours at 4℃,20℃,40℃after adding protection additive in enriched cell.Then the freeze-drying livability is measured subsequently.It was confirmed that the one-hour preincubation at 40℃has relative ideal effect.The ideal selected protectant is composed of 3%NFM,3%lactose and 3%glycerol.Under the mentioned condition,the freeze-drying livability can attached to 75.5%.Additionally, the yogurt produced with the freeze-drying cell powder which is made in the mentioned conditions satisfied the requirements.