Hemicellulose and lignin removal to improve the enzymatic digestibility and ethanol production

Abstract

Fourteen herbaceous energy crops were selected to investigate their recalcitrance to cellulosic enzyme. The results about enzymatic hydrolysis of sorghum and Pennisetum hybrids indicated that both hemicellulose and lignin content had a negative influence on enzymatic digestibility (ED), especially for the latter.Furthermore, liquid hot water (LHW) and aqueous ammonia (AA) methods were applied to enhance the ED of sugarcane bagasse (SCB). A high ED of 90% was obtained for sample with 50% removal of xylan and lignin in the AA process, which was 20% higher than that of LHW due to the significant removal of lignin hindering and exposing of fibers. However, the total sugars recovery of LHW were about 10% higher than that of AA resulted to the high yield of hemicellulose-derived sugars.Moreover, SCB hemicellulose and lignin were removed with the help of LHW and following AA process. The ethanol concentration reached to 30.6 g/L after a fed-batch enzymatic hydrolysis following simultaneous saccharification and fermentation process with a high substrates loadings of 20% (w/v), low enzyme loading of 20 FPU/g glucan, and low fermentation time of 24 h.