Abstract: Wet brewer’s spent grain was dried to the water content around 10%,and then smashed with the undersized machine. After 20 to 40 mesh screening,grains were soaked with 0.80% H2SO4 for 10 h at the ratio of solid to liguid 1:11,and then were prehydrolyzed for 90 min at 121 ℃. The pre-hydrolysates were hydrolyzed with 0.20% cellulase(W/V) for 5 h at 50 ℃ after adjusting pH to around 4.0 with 2.0 % NaOH,and the hydrolysate with 8.82 % reducing sugar content was obtain. After adjusting pH to around 6.0,the hydrolysate added with 5.0 % CaCO3 was fermented at 55 ℃ by batch feeding,and the yield of L-lactic acid in the fermentation broth is 80.75 g/L.

Key words: brewer&rsquo, s spent grains； enzymic hydrolysis； lactic acid fermentation