Optimization of Immobilization Conditions of Wickerhamomyces anomalus Y5-5 and Its Effect on the Wine Making Process

In order to stabilize the activity of ester-producing yeast and elevate the total ester yield of raw liquor,the immobilization conditions of Wickerhamomyces anomalus Y5-5 was optimized by single factor and orthogonal test successively,and the effect of immobilized yeast on brewing process were analyzed. The results showed that the optimization conditions were sodium alginate concentration 3%,calcium chloride concentration 2.0 mol/L,immobilization temperature 25 ℃,yeast cell concentration 10⁹/mL. Under this conditions,the residual sugar reduced to(2.73±0.05) g/L,a very low level meant the immobilization had a better effect. In the brewing experiment with immobilized yeast and free yeast,the total acid,alcohol content and pH of the zymotic fluids have no significant differences,but the total ester reached to 3.4 g/L,which was about twice of that of the control group. It indicated that the reticular structure formed from sodium alginate and calcium chloride could protect the ester-producing yeast cell during fermentation,increased the ester yield of fermented grains effectively,and had a great significance for improving the quality of light-flavor Baijiu.