Abstract: This study describes the optimization of the formulation of cryoprotectants for Bifidobacterium lactis Z-1 using response surface methodology (RSM). Using the Plackett-Burman design, trehalose, sucrose, L-cysteine hydrochloride concentration were identified as factors with a significant influence on the viable count of lyophilized Bifidobacterium lactis Z-1. Subsequently, the optimal response ranges of the three factors were determined using the steepest ascent method. The levels of these factors were further optimized using RSM with Box-Benhnken design. As a result, a regression model was fitted into the experimental data. The optimal levels of trehalose, sucrose and L-cysteine hydrochloride were determined as 200.51, 46.16 and 2.31 g/L, respectively, while the other ingredients were the same as those in the traditional recipe (skimmed milk powder 100 g/L, whey protein powder 20 g/L, glycerol 4 g/L, sodium isoascorbate 10 g/L and sodium glutamate 8 g/L).

Key words: Bifidobacterium lactis Z-1, Plackett-Burman design, steepest ascent method, response surface methodology; cryoprotectants

摘要： 采用响应面法对乳双歧杆菌Z-1冷冻干燥保护剂配方进行优化。通过Plackett-Burman试验与最陡爬坡试验确定影响乳双歧杆菌Z-1冷冻干燥后活菌数的显著因素及最优响应值区间，再通过Box-Benhnken试验优化得到乳双歧杆菌Z-1冷冻干燥保护剂最佳配方。结果表明：海藻糖、蔗糖、L-半胱氨酸盐酸盐添加量是影响乳双歧杆菌Z-1冷冻干燥后活菌数的显著因素；经响应面试验设计建立活菌数和海藻糖、蔗糖、L-半胱氨酸盐酸盐添加量的回归模型，得到乳双歧杆菌Z-1冷冻干燥保护剂最佳配方为海藻糖添加量200.51 g/L、蔗糖添加量46.16 g/L、L-半胱氨酸盐酸盐添加量2.31 g/L，其他成分不变（脱脂乳粉添加量100 g/L、乳清蛋白粉20 g/L、甘油4 g/L、异抗坏血酸钠10 g/L、谷氨酸钠8 g/L）。

关键词: 乳双歧杆菌Z-1, Plackett-Burman试验, 最陡爬坡试验, 响应面试验, 冷冻干燥保护剂