Optimization of Yeast Lyophilization Protectant Based on Oat β-glucan
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Abstract:
To improve the survival rate of freeze-dried yeast, Saccharomyces cerevisiae was selected as the research object, and the survival rate of the strain was the corresponding index. The main freeze-dried cryoprotector was oat β-glucan, which was combined with γ-poly-glutamic acid and mannitol. The single factor rotation test was used to determine the level of three factors and serve as the central point of response surface optimization test. The regression equation between the survival rate of yeast and the three factors was established by Central Composite response surface method. The effects of various factors on the response values were analyzed by response surface analysis, and the morphology of lyophilized yeast cells was observed by scanning electron microscope. The results showed that the best ratio of cryoprotectores was 6.56% oat β-glucan, 0.15% γ-poly-glutamic acid, 1.15% mannitol, and the mass ratio of bacteria to protective agent was 1:2. Under these conditions, the survival rate of cells could reach 90.69%, which was close to the theoretical predicted value of 89.86%. Compared with the yeast cells without adding cryoprotector, the yeast cells in the group with adding cryoprotector were full in morphology and complete in structure. The results of this study can provide data support for the freeze-drying protection and promotion of yeast.
