乳酸菌代谢保护剂中糖产酸对冷冻保护的影响  

Effect of acids produced by metabolizing carbohydrate of protectants on viability of Lactobacillus during freezing

作　　者：崔树茂[1] 赵建新[1] 陈卫[1] 张灏[1] 

机构地区：[1]江南大学食品学院,江苏无锡214122

出　　处：《食品与发酵工业》2017年第3期14-19,共6页Food and Fermentation Industries

基　　金：十二五国家科技支撑项目:发酵乳制品乳酸菌菌种与发酵剂的研究与开发

摘　　要：真空冷冻干燥是乳酸菌菌粉制备的关键技术手段,在冻干前须将菌泥与保护剂混匀并进行预冻。文中系统研究了菌泥与保护剂混匀过程中的代谢产酸情况,及产酸引起的pH值降低对预冻的影响。测定了不同菌泥添加保护剂后在室温和冷藏温度下的产酸速率,以及不同pH值下冷冻后菌株的存活率,分析了不同pH值条件下冷冻对菌株ATP酶、β-半乳糖苷酶、乳酸脱氢酶及细胞膜完整性和流动性的影响。结果表明,菌泥与保护剂混合后,室温环境下的产酸速率很快,可在短时间内将菌悬液的pH值降至4.0。而pH值降低确实会对冷冻菌株的存活产生影响,pH值在降至4.0时,菌株冷冻存活率显著降低。低pH值条件下的冷冻,会损伤ATP酶、β-半乳糖苷酶及降低细胞膜的流动性,是导致冷冻存活率降低的原因。因此,为提高真空冷冻干燥的菌株存活率,首先须控制菌泥与保护剂混合时的温度和时间,确保预冻阶段乳酸菌无损失。Vacuum freeze-drying is the key technology for preparing Lactobacillus powder. It is significant for cell pastes to be mixed with protectants before freeze drying. In this paper,the acid production rate in the mixing processing of cell pastes and protectants,and the effect of pH decrease caused by acid production on viability of Lactobacillus during freezing,were studied. The rate of acid production at room temperature and cold storage temperature,as well as the survival rate of Lactobacillus at different pH value after freezing,were determined. In addition,ATPase,β-galactosidase,lactate dehydrogenase（ LDH）,and cell membrane integrity and fluidity of Lactobacillus after freezing at different pH were measured. The results showed that the rate of acid production at room temperature was very fast,which could reduce the pH of the bacterial suspension to 4. 0 in a short time after mixed with protectants. The low pH indeed decreased the survival rate of frozen strains,which was significantly reduced at pH 4. 0. The damage of ATP enzyme and β-galactosidase,and the reduction of the fluidity of cell membrane caused by freezing under low pH could result in the low survival rate. Therefore,the temperature and time for mixing cell pastes with protectants must be controlled to avoid loss of lactic acid bacteria in pre-freezing stage in order to improve the survival rate during vacuum freeze drying.

关 键 词：乳酸菌 产酸速率 存活率 酶 

分 类 号：TS201.3[轻工技术与工程—食品科学]