Patent ID: 8192968

Claim:
A method for obtaining a fermentation product from a sugar hydrolysate obtained from a feedstock comprising hemicellulose, comprising: (i) removing suspended fiber solids from the sugar hydrolysate to obtain a clarified sugar solution; (ii) fermenting xylose in the clarified sugar solution in a fermentation reaction with yeast to produce a fermentation broth comprising a fermentation product; (iii) separating the yeast from the fermentation broth to produce a yeast slurry and a fermentation product, (iv) treating the yeast slurry with an oxidant to reduce microbial contaminants in the yeast slurry, thereby producing oxidant-treated yeast slurry; (v) re-introducing at least a portion of the oxidant-treated yeast slurry back to the step of fermenting, step (ii), to increase the concentration of yeast in the fermentation reaction; and (vi) recovering the fermentation product.