益生菌干酪乳杆菌LC-15生长及发酵特性研究

Biological and Fermentation Properties of the Lactobacillus casei LC-15

益生菌发酵剂对于益生菌发酵乳制品的开发与应用有很重要的研究意义,对一株具有降低胆固醇作用的益生菌干酪乳杆菌LC-15(Lactobacillus casei LC-15)进行生长发酵特性的研究。通过对干酪乳杆菌LC-15的生长及发酵特性的测定:确定了干酪乳杆菌LC-15在复原脱脂乳中凝乳需10h,12h时pH达到4.5,滴定酸度达到81.5°T,最适生长温度为38℃;药敏实验表明,干酪乳杆菌LC-15对四环素、氯霉素和红霉素高度敏感;该菌发酵乳所含挥发性风味物质中酮类物质与各类挥发性脂肪酸总含量分别达到了35.91%和52.52%;干酪乳杆菌LC-15发酵乳在前期发酵中酸度变化不大,有一定程度的后酸化现象;在pH4.0的PBS缓冲溶液4℃贮存10d总菌落下降近一个数量级;干酪乳杆菌LC-15在与其他发酵菌以3:1:1混合培养时,在39℃培养条件下6h开始凝乳,比干酪乳杆菌LC-15单菌发酵缩短4h。

Probiotic starter culture plays an important role in developing probiotic yoghurt or fermented dairy products. In this paper, the biological and fermentation properties of the cholesterol-reducing probiotic strain Lactobacillus casei LC-15 was studied. Results showed that： the fermented RSM was coagulated at 10 h, the high pH 4.5 was obtained at 12 h, titratable acidity was 81.5°T, and the optimal growth temperature is 38 ℃; antibiotic sensitivity test found that the strain showed significantly sensitive to tetracycline, chloramphenicol and erythromycin; volatile flavor components analysis showed the major compounds are ketone and volatile fatty acid, their proportion are 35.91%and 52.52%; the acidity of fermented milk changed indistinctively in 0 to 7d, and became 0.16% higher at 14 d, having the post-acidify profile; when stored in PBSbuffer （pH 4.0） at 4℃ for 10 days, the viable cells changed from 6.35×10^7 to 5.61×10^6 cfu/mL. Mixed fermentaion of Streptococcus thermophilus, Lactobacillus bulgaricus and Lactobacillus casei LC-15 study showed optimal conditions are 1：1：3 with inoculum of 3% at 39 ℃, the coagulated time was 4 h less than single fermentation.