双歧杆菌冻干菌粉制备工艺的研究

优化双歧杆菌冻干菌粉的制备工艺及检测冻干菌粉在模拟人体胃肠环境中的耐受性和贮存稳定性，采用3 种方法制备双歧杆菌冻干菌粉。方法1：双歧杆菌在牛奶还原培养基中的扩大培养液加入甘露醇作为保护剂制备冻干菌粉；方法2：双歧杆菌在PTYG 培养基中的扩大培养液经低温离心得到菌泥，向菌泥中加入保护剂甘露醇、增量赋形剂脱脂乳粉制备冻干菌粉；方法3：同方法2 得到菌泥，向其中加入保护剂甘露醇、包埋剂明胶及增量赋形剂脱脂乳粉制备冻干菌粉。由方法2 得到菌粉活菌数较高，为1.31 × 1010CFU/g；经模拟胃肠环境处理后，活菌数仍保持在4.19 × 108CFU/g；对胃酸、胆汁酸具有很高的耐受力。经典加速实验证明由方法2 制备的菌粉室温保存1 年以上活菌数仍保持在107 数量级，具有较好的贮存稳定性。

Preparation of Lyophilized Bifidobacterium bifidum Powder

This study investigated the preparation of lyophilized powder of Bifidobacterium bifidum and assayed its tolerance to simulated human gastrointestinal environment and stability during storage at 37 ℃. Three methods used to prepare lyophilized powder of Bifidobacterium bifidum were described as follows: Method 1: B. bifidum strain was amplified by culturing in reconstituted milk based medium and mannitol was then added as cryoprotectant to prepare lyophilized powder; Method 2: B. bifidum strain was amplified by culturing in PTYG medium and a bacterial mud was then obtained after hypothermal centrifugation. Finally, mannitol as cryoprotectant was added to the bacterial mud to prepare lyophilized powder; Method 3: A bacterial mud obtained as described in Method 2 was added with mannitol as cryoprotectant, gelatin as embedding medium, skim milk powder as excipient to prepare lyophilized powder. The results indicated that a higher viable count was observed in the lyophilized powder prepared by Method 2, which was up to 1.31 × 1010 CFU/g and although exposed to simulated gastrointestinal environment, the lyophilized powder exhibited a viable count of up to 4.19 × 108 CFU/g, which suggests that the lyophilized powder has excellent tolerance to gastric acid and bile acid. The classic accelerated experiment proved that the lyophilized power obtained Method 2 had good stability during storage at 37 ℃ and the viable count still kept at a magnitude of 107 after storage for up to one year.