Method for efficiently producing lactic acid by fermenting brewers' spent grains

Abstract

The present disclosure relates to a method for efficiently producing lactic acid by fermenting brewers' spent grains. The method specifically includes the following steps: (1) adding water to brewers' spent grains after alkali pretreatment so as to adjust a solid content of a fermentation production system to 10%-15%, adding cellulase to the brewers' spent grains according to an addition amount of 5 FPU/g-10 FPU/g, carrying out hydrolysis at 50° C.-60° C. and pH of 4.5-5.2 for 20 hours-48 hours, and obtaining a prehydrolyzed substrate; and (2) inoculating hydrolysate prepared in step (1) with a lactic acid bacteria seed solution with a viable count of 1×10CFU/mL-1×10CFU/mL according to an inoculation amount of 10%-15% (v/v), conducting fermentation at 40° C.-55° C. and pH of 6.0-7.2 for 72 hours-96 hours, and obtaining a fermentation broth.