低浓度的酸碱及双酶解预处理对麦糟发酵乙醇的影响

Fermentation of Brewers' Spent Grain Pretreated by Acid or Alkali with Dilute Concentration and Two-Hydrolases to Produce Alcohol

研究综合利用木质纤维三大组分的生物转化过程。将麦糟的醇不溶物按料液比1:8(W/V)加入0.1 mol·L-1NaOH,浸泡24 h,264 W微波处理20 min后,调pH 5.0、45℃,加50 U·mL-1的木聚糖酶粗酶液反应12 h后,再加入40 mU·mL-1的阿魏酸酯酶粗酶液反应12 h,将沉淀洗至中性,烘干,乙醇抽提,得到酶降解后麦糟的醇不溶物残渣。此残渣在料液比1:40(W/V),纤维素酶量200 U/g(麦糟的醇不溶物),反应时间36 h,初始pH值为4.5,50℃条件下进行水解,此残渣的纤维素酶解糖化率为78.5%。将残渣的水解液进行乙醇发酵,其乙醇的产量为0.27 g g 1(麦糟的醇不溶物),对应的转化率为48.72%,为理论纤维素的糖转化率的86.06%。实验结果表明经低浓度的酸碱及双酶解预处理的麦糟,经纤维素酶酶解,发酵乙醇是可行的,此研究为木质纤维的综合利用提供应用研究基础。

This paper deals with the biological transformation process of the three main ingredients in lignocellulose.Alcohol-insoluble residue（AIR） of brewers’ spent grain（BSG） was put into the 0.1 mol·L-1 NaOH solution at the ratio of 1：8（W/V） and soaked for 24 h.After being treated with 264 W microwave for 20 min,the sample reacts with crude enzyme solution of xylanase（50 U·mL-1） at pH 5.0 and 45℃ for 12 h.Then the crude enzyme solution of feruloyl esterase（40 mU·mL-1） was added and reacts with the sample for another 12 h.The enzyme-treated BSG-AIR was obtained by eluting,drying,and ethanol extracting the precipitate obtained by above-mentioned process.The obtained sample was hydrolyzed with cellulose（200 U per g AIR-BSG） at the ratio of 1：40（W/V）,pH 4.5 and 50℃ for 36 h,and its saccharification ratio is 78.5%.The hydrolyzate of AIR-BSG was fermented and the ethanol product of 0.27 g g 1AIR-BSG） was obtained,the corresponding conversion ratio is 48.72%,which is 86.06% of the theoretical one.Our results show that it is feasible for BSG fermentation to produce alcohol via pretreating the BSG with dilute concentration of acid or alkaline and two kinds of enzymatic hydrolyses.It may provide foundation for research on the multipurpose use of the lignocellulose.