Response Surface Optimization of Lyoprotectant from Amino Acids and Salts for Bifidobacterium Bifidum During Vacuum Freeze-Drying

High quality probiotic powder can lay the foundation for the commercial production of functional dairy products. The freeze-drying method was used for the preservation of microorganisms, having a deleterious effect on the microorganisms viability. In order to reduce the damage to probiotics and to improve the survival rate of probiotics during freeze-drying, the Response Surface Methodology (RSM) was adopted in this research to optimize lyoprotectant composed of amino acids (glycine, arginine) and salts (NaHCO₃ and ascorbic acid). Probiotic used was Bifidobacterium bifidum BB01. The regression model (p<0.05) was obtained by Box–Behnken experiment design, indicating this model can evaluate the freeze-drying survival rate of B. bifidum BB01 under different lyoprotectants. The results indicated these concentrations as optimal (in W/V): glycine 4.5%, arginine 5.5%, NaHCO₃ 0.8% and ascorbic acid 2.3%, respectively. Under these optimal conditions, the survival rate of lyophilized powder of B. bifidum BB01 was significantly increased by 80.9% compared to the control group (6.9±0.62%), the results were agreement with the model prediction value (88.7%).