Pennisetum hybrid I, II and switchgrass were pretreated with liquid hot water to enhance the release of
sugars. The optimum hydrolysis factor for three energy grasses was 5.98, and the total xylose yield was
88.4%, 98.1% and 83.6% for grass I, II and S. It was indicated that the ratio of syringyl and guaiacyl units of
lignin played an important role on the hemicellulose hydrolysis in LHW than branch degree, but latter
contributed more on the characterization of xylooligomers degree of polymerization. Moreover, the analysis
of multi-scale changes of substrate suggested that cellulose crystallinity index and degree of
polymerization seemed no direct relationships for increase of enzymatic digestibility. While lignin barrier
was the main factor limiting efficiency of sugar release, and Pennisetum hybrid with low lignin content
and high sugar recovery was proved to be a prospective plant feedstock for cellulosic ethanol production.
2015 Elsevier Ltd. All rights reserved.