乳酸乳球菌乳脂亚种冷冻干燥保护剂优化及其贮藏稳定性

采用单因素试验、Plackett-Burman试验设计和Box-Behnken响应面法，筛选和优化乳酸乳球菌乳脂亚种KLDS4.0326真空冷冻干燥保护剂工艺，并分析冻干菌粉在不同温度下的贮藏稳定性。结果表明：脱脂乳粉、海藻糖和甘油含量是影响菌体细胞存活率的关键因素；以菌体细胞存活率为响应值，对3 个因素进行优化分析，保护剂最佳配比为：脱脂乳粉10.77 g/100 mL、海藻糖7.81 g/100 mL、甘油3.31 g/100 mL，此条件下菌体细胞存活率为（87.43±1.62）%，与理论预测值接近。在4 ℃和25 ℃条件下保藏12 个月后，菌体细胞存活率分别为40.63%和8.67%，冻干菌粉在4 ℃条件下具有更高贮藏稳定性。

Optimiztion of Cryoprotectants for Lactococcus lactis subsp. cremoris KLDS 4.0326 and Its Storage Stability

The formulation of cryoprotectants for Lactococcus lactis subsp. cremoris KLDS 4.0326 was optimized by
combined use of single-factor, Plackett-Burman and Box-Behnken response surface designs, and the storage stability at
different temperatures of bacterial powder made with the optimized cryoprotectants was analyzed. The results indicated
that the survival rate was significantly affected by skim milk powder, trehalose and glycerol. By regression analysis of
the obtained experimental data, the optimum cryoprotectant formulation was composed of skim milk powder, trehalose
and glycerol at concentrations of 10.77, 7.81 and 3.31 g per 100 mL water, respectively for maximum cell survival rate of
(87.43±1.62)%, which was close to the theoretical prediction. After the bacterial cells were stored at 4 and 25 ℃ for 12
months, their cell survival rates were 40.63% and 8.67%, respectively. Therefore, the freeze-dried bacterial powder had a
relatively higher storage stability at 4 ℃.