Abstract: The formula of cryprotectants for Lactobacillus plantarum was optimized by 2-Level factorial design and central composite design (CCD). The results indicated that the skim milk, trehalose , and MnSO4 are three key factors, which contribute to the survival of the cells after cryodesiccation. By CCD design and response surface analysis, the quadratic model for the three significant factors was established with cell survival rate as the target response. The optimal formula obtained is skim milk 3.34%, trehalose 1.85% and MnSO4 0.25%, and the cell survival rate reaches 96.8%±1.3%.

Key words: response surface methodology (RSM), Lactobacillus plantarum, cryprotectants, direct-to-vat starter (DVS)