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Co-extraction of soluble and insoluble sugars from energy sorghum based on a hydrothermal hydrolysis process

Yu, Qiang, Tan, Xuesong, Zhuang, Xinshu, Wang, Qiong, Wang, Wen, Qi, Wei, Zhou, Guixiong, Luo, Yu, Yuan, Zhenhong
Bioresource technology 2016 v.221 pp. 111-120
arabinose, biomass production, cell walls, cellulose, chemical composition, crystal structure, energy, enzymatic hydrolysis, hemicellulose, hydrolysis, lignin, xylose
A process for co-extraction of soluble and insoluble sugars from energy sorghum (ES) was developed based on hydrothermal hydrolysis (HH). Two series of ES were investigated: one (N) with a high biomass yield displayed a higher recalcitrance to sugar release, whereas the second (T) series was characterized by high sugar extraction. The highest total xylose recoveries of 87.2% and 98.7% were obtained for N-11 and T-106 under hydrolysis conditions of 180°C for 50min and 180°C for 30min, respectively. Moreover, the T series displayed higher enzymatic digestibility (ED) than the N series. The high degree of branching (arabinose/xylose ratio) and acetyl groups in the hemicellulose chains of T-106 would be expected to accelerate sugar release during the HH process. In addition, negative correlations between ED and the lignin content, crystallinity index (CrI) and syringyl/guaiacyl (S/G) lignin ratio were observed. Furthermore, finding ways to overcome the thickness of the cell wall and heterogeneity of its chemical composition distribution would make cellulose more accessible to the enzyme.