Wu Wentao, Ju Meiting, Liu Jinpeng, Liu Boqun
College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park 16802, United States.
Sheng Wu Gong Cheng Xue Bao. 2016 Apr 25;32(4):457-467. doi: 10.13345/j.cjb.150335.
Ensilage is a traditional way of preserving fresh biomass. However, in order to apply ensilage to the ethanol biorefinery, two parameters need to be evaluated: quantity and quality changes of the biomass; and its effects on bioconversion process. To study these two aspects, switchgrass harvested on three different time points (Early, mid and late fall) were used as feedstock. The early fall harvested biomass was ensiled at 5 moisture levels ranging from 30% to 70%. Silage of 40% moisture and 3 other raw switchgrass were pretreated with liquid hot water, followed by enzymatic hydrolysis as well as simultaneous saccharification and fermentation. After 21 days storage pH values of all silages decreased below 4.0 and the dry matter losses were less than 2.0%, and structural sugars contents did not change dramatically. Liquid hot water caused more hemicellulose dissolution in the silage than in unensiled switchgrass. However, ensilage also increased the risk of releasing more sugar degradation products; After enzymatic hydrolysis, silage obtained higher total glucose, xylose and galactose yields than raw materials; After simultaneous saccharification and fermentation, ethanol concentration in silage was 12.1 g/L, higher than the unensiled switchgrass (10.3 g/L, 9.7 g/L and 10.6 g/L for early, mid and late fall respectively). Our results suggest that ensilage helps increase pretreatment efficiency and sugar yield, which increases final ethanol production.
青贮是保存新鲜生物质的传统方法。然而，为了将青贮应用于乙醇生物精炼厂，需要评估两个参数：生物质的数量和质量变化；以及其对生物转化过程的影响。为了研究这两个方面，将在三个不同时间点（初秋、中秋和晚秋）收获的柳枝稷用作原料。初秋收获的生物质在5个水分水平（30%至70%）下进行青贮。将40%水分的青贮料和其他3种未青贮的柳枝稷用液态热水预处理，然后进行酶水解以及同步糖化发酵。储存21天后，所有青贮料的pH值均降至4.0以下，干物质损失小于2.0%，结构糖含量没有显著变化。液态热水使青贮料中半纤维素的溶解比未青贮的柳枝稷更多。然而，青贮也增加了释放更多糖降解产物的风险；酶水解后，青贮料获得的总葡萄糖、木糖和半乳糖产量高于原料；同步糖化发酵后，青贮料中的乙醇浓度为12.1 g/L，高于未青贮的柳枝稷（初秋、中秋和晚秋分别为10.3 g/L、9.7 g/L和10.6 g/L）。我们的结果表明，青贮有助于提高预处理效率和糖产量，从而提高最终乙醇产量。
