Lactobacillus paracsei L9冷冻保护剂的优化

The optimization of cryogenic protectant for Lactobacillus paracasei L9

副干酪乳杆菌L9(Lactobacillus paracsei L9)是1株具有突出益生功能及生产性能的益生菌菌株,现阶段高性能发酵剂的制备是其成功应用于工业化生产的关键技术。而液氮深冷技术是高性能发酵剂制备的有效手段,其中保护剂的应用是液氮深冷工艺的关键因素。该研究以菌种存活率作为评价指标,在已有研究基础上对液氮深冷保护剂种类进行筛选,对保护剂浓度进行正交优化,并确定菌体与保护剂最佳混合比例。结果表明脱脂乳粉、果糖、海藻酸钠及Vc四种保护剂能对副干酪乳杆菌L9起到良好的保护作用;通过正交实验优化了保护剂配方:脱脂乳粉质量分数为10%,果糖质量分数为5%,海藻酸钠质量分数为5%,Vc质量分数为0.075%,可使菌体冷冻后存活率达到(92.23±0.86)%,显著提高在冻藏过程中菌体的存活率(P<0.05),较好地优化了Lactobacillus paracsei L9发酵剂的制备技术,并为实际的生产提供了理论依据。

Lactobacillus paracsei L9 was a probiotic strain with health benefit and productive performances. The preparation of high-performance starter was the key technology for successful application in industrial production. To improve starter＇s activity, the liquid nitrogen cryogenic treatment was employed in the preparation of starter cultures, and protective agents were important to strain activity during the liquid nitrogen cryogenic process. The optimal formu- la of cryoprotectant was determined by single-factor experiments. Then the concentration of preferred cryoprotectant was optimized by orthogonal test. The definitive protection formulations were to （skim milk powder） 10% ,to （fructose） 5% ,to（alginate） 5%, and to（Vc） 0. 075%. The viability of bacteria cells could reach （92.23±0.86）% after freezing with our eryoprotectant. It indicated that the optimized cryoprotectant could improve the viability of L9 cells during the freezing and storage process.