The invention relates to
Saccharomyces cerevisiae and a preparation method thereof. A preparation method of high-
nitrogen fresh
yeast is mainly characterized by comprising the following steps of: (1) preparing a strain, i.e.,
Saccharomyces cerevisiae which is collected in the China General
Microbiological Culture Collection Center with the collection number of CGMCC No.5004; (2) preparing a culture medium in a certain
mass ratio; (3) pretreating
sweet sorghum juice; (4) fermenting; (5) undergoing an adaptive phase at the ventilation quantity of 0.8-1.2 V.V.m and the stirring speed of 300-500 r / min for 4-6 hours, and adding nutritional salts, including 0.2-3 percent of (NH4)2SO4, 0.03-1.5 percent of MgSO4 and 0.2-1.5 percent of KH2PO4; (6) undergoing an
exponential growth phase for 10-20 hours, fermenting at the fermenting temperature of 32-35 DEG C, undergoing a decline phase at the ventilation quantity of 0.3-0.5 V.V.m and the stirring speed of 80-150 r / min, stopping feeding
liquid glucose, measuring the concentration of residual
sugar in fermented cheese liquid, and stopping fermenting if the concentration of residual
sugar is less than 0.5 percent; and (7) treating a
fermentation liquid. In the method, the
sweet sorghum juice is taken as a
carbon source in the
fermentation liquid. Compared with other
carbon source culture mediums such as honey and beet, the
sweet sorghum juice has the advantages of simple pretreating process, saving in
energy consumption and increase in production efficiency.