In addition to the influence of pretreatment severity on the recovery yield and chemical composition of elephant grass, changes were also observed in the physical structure of steam-treated biomass. Fig. 1S (Supplementary material) presents the morphological analysis of both untreated and steam-exploded elephant grass by scanning electron microscopy. Samples that were pretreated at higher temperatures suffered greater fragmentation and these changes increased the accessibility of cellulose to the subsequent enzymatic hydrolysis. Also, these morphological changes agreed well with the observed mass loss (Table 2). With a decrease in biomass particle size at increasing temperature and extraction time, higher concentrations of low molar mass compounds were observed in the water solubles, such as in the case of xylose and arabinose (Table 3A).