干酪乳杆菌T1发酵方法及其热冲击研究

Method of fermentation and thermal shock study of Lactobacillus casei T1

从青藏高原牧区的牦牛酸乳中分离出一株产细菌素的干酪乳杆菌T1(Lactobacillus casei T1),作为添加剂加入食品中,能够抑制细菌的生长,具有食品防腐的作用。从生产条件出发,探索其作为食品添加剂的最适发酵条件并进行5 t发酵罐的扩大培养,以及针对菌粉制作过程常用喷雾干燥法进行的最适热冲击条件探索。结果表明,L.casei T1最适培养温度为32℃;控制p H5.5条件下发酵能有效促进菌体生长;按原培养基中碳源和氮源总含量的5%对培养基进行补料,发酵液OD600 nm及活菌数也有较大提升;在5 t发酵罐中扩大培养,活菌数达到8.3×109 cfu/m L。对提高L.casei T1耐热性的热冲击研究结果显示,对照组L.casei T1菌液不进行热冲击,直接置于60℃水浴锅中12 min热致死,菌体存活率为0.01%,而按最适热冲击条件即52℃、30 min条件下对L.casei T1菌液热冲击后再置于60℃水浴锅中12 min热致死,菌体存活率达到10%,表明合适的热冲击条件能有效解决乳酸菌在加工贮藏时成为技术瓶颈之一的活菌数稳定性问题。

A strain of Lactobacillus casei T1 that can stably produce bacteriocin was isolated from the Tibetan plateau yak yogurt. As an additive into the food, there is a certain antibacterial and preservative. We studied the efficient preparation technology of high activity Lactobacillus casei. The results showed the optimal cultivation temperature of T1 was 32 ℃. pH 5.5 and 5% medium supplement can effectively promote the growth of T1, and the number of live bacteria-I received 8.3x109 cfu/mL which was cultivated in 5 t fermentation tank. The thermal shock study to improve thermal stability of T1 showed： compareing to 0% of survival rate heated under the condition of 60 ℃, 12 min, thermal shock under the condition of 52 ℃, 30 min, the survival rate under the condition of 60 ℃, 12 min increased to 10%, which will be effectively solve the problem of living bacterium stability of lactic acid bacteria in processing and storage which becomes one of the technical bottleneck.