本文研究了水分含量和水分活度（Aw）对干酪乳杆菌LC-134（简称LC-134）冻干粉在贮存过程中的稳定性影响。将不同水分含量和Aw的LC-134冻干粉分别在-18 ℃和25 ℃条件下贮存12个月和6个月，定期测定LC-134冻干粉中的活菌数的变化趋势，并且探讨保护剂中的聚葡萄糖含量对冻干粉的水分含量和Aw的影响；研究表明，贮存于-18 ℃条件下、LC-134冻干粉水分含量≤(5.14±0.06)?10-2 g/g或者Aw≤0.31±0.01时，在贮存的12个月中，活菌数没有明显的下降；然而，贮存于25 ℃条件下达到活菌数稳定，则要求LC-134冻干粉的水分含量低于(3.06±0.05)?10-2 g/g或者Aw低于0.25±0.01。聚葡萄糖的添加，可降低水分含量相同的LC-134冻干粉的Aw，而且水分含量越高，这种作用越明显。

The effects of moisture content and water activity (aw) on the storage stability of Lactobacillus casei LC-134 (LC-134) lyophilized powder were studied. LC-134 lyophilized powders with different moisture contents and aw values were stored at -18 ℃ for 12 months and at 25 ℃ for six months, respectively. Viable cell count variation of the powders were measured regularly, and the influence of polydextrose concentration in the lyoprotectant on the moisture content and aw of the powders was explored. The results showed that during 12 months of storage at -18 ℃, no significant decrease was found in the viable cell counts of the LC-134 lyophilized powders with a moisture content of less than (5.14±0.06)?10-2 g/g or an aw value of less than 0.31±0.01. However, the viable cell count was stable at 25 ℃ during six months of storage if the moisture content was less than (3.06±0.05)?10-2 g/g or aw was less than 0.25±0.01. The addition of polydextrose could reduce the aw value of LC-134 lyophilized powders with the same moisture content. Moreover, the higher the moisture content, the more significant the effect.

2016年广州市科技型中小企业技术创新资金专项（初创项目）（2015051439494）