热休克处理对直投式乳酸菌发酵剂在不同贮存温度下存活率的影响

以嗜酸乳杆菌为代表菌种, 利用快速保质期试验法, 研究热休克处理结合冻干保护剂对直投式乳酸菌发酵剂在不同贮存温度下存活率的影响 以筛选出存活率最高的冻干保护剂, 并确定冻干后菌粉半致死时间最长的贮存温度. 结果表明: 乳酸菌在冷冻干燥前进行热休克预处理, 冻存期间存活率显著高于未进行热休克处理的对照组; 冻干保护剂效果由高到低依次为: 10脱脂乳>10葡萄糖>水; 贮存温度降低, 乳酸菌半致死时间延长. 最后获得直投式发酵剂贮存期间存活率最高的实验条件为: 嗜酸乳杆菌经46处理30min后, 加入10葡萄糖、2.5甘油、1.5山梨糖醇以及10脱脂乳为冻干保护剂 冻干后菌粉于20℃冻存121d后存活率达88.48, 与以水为冻干保护剂且未加热休克处理的对照组相比, 冻干存活率提高了30.69.

Effect of heat shock treatment on survival rate of direct vat set Lactobacillus acidophilus starter at different storage temperatures

In the current study, Lactobacillus acidophilus was used as the representative strain. ASLT was used to investigate the effect of heat shock treatment combined with lyoprotectant on the survival rate of direct vat set lactic acid bacteria starter at different storage temperatures. The lyophilized protective agent with the highest survival rate and the storage temperature of the longest lethal time of the powder after lyophilization was determined. The results showed that the lactic acid bacteria were subjected to heat shock pre-treatment before freeze-drying. The survival rate during cryopreservation was significantly higher than that in the control group without heat shock treatment. The order of lyophilization protection effect was from high to low: 10% skim milk>10% glucose>water. The decreased storage temperature increased the semi-lethal time of the lactic acid bacteria. Finally, the experimental conditions for obtaining the highest survival rate during the storage of the direct-injection starter include treatment with Lactobacillus acidophilus for 30 min at 46℃, followed by adding 10% glucose, 2.5% glycerol, 1.5% sorbose and 10% skim milk for lyophilization. The granules were frozen at -20℃ after lyophilization, and the survival rate reached 88.48% after 121 days, and the freeze-drying survival rate was increased by 30.69% compared with the control group treated with water as a lyoprotectant and without heat shock