The chemical composition of elephant grass before and after pretreatment has been already reported elsewhere (Scholl et al.,
2015). In general, steam explosion modified the chemical composition of elephant grass primarily by decreasing its hemicellulose content as previously observed for other lignocellulosic materials such as cane bagasse (Pitarelo et al., 2012) and Eucalyptus grandis (Emmel et al., 2003). Most of the hemicellulose sugars that were released by acid hydrolysis during steam explosion were recovered in the primary and secondary water soluble fractions, which were obtained from the steam-treated materials by filtration and extensive water washing, respectively. Hemicellulose removal reflected in an increase in both glucan (mostly cellulose) and lignin contents in the steam-treated cellulosic substrate. Hence, hemicelluloses were the most severely affected biomass component during steam explosion and this explains the high concentration of pentose sugars in the water solubles, even at relatively mild pretreatment
conditions (Pitarelo et al., 2012).