Acid hydrolysis of this grass decreased the hemicellulose content
in the solid phase due to solubilization. It has been reported
that the acid hydrolysis of lignocellulosic materials solubilizes
the hemicellulosic fraction by altering the covalent bonds, hydrogen
bonds and van de Walls forces of this fraction [16]. This process
also leads to the formation of degradation compounds which
may have an inhibitory effect on the enzymatic hydrolysis and fermentation.
Table 2 shows a decreased lignin content in the solid
phase of elephant grass pretreated by dilute acid; this could be
possibly due to a partial hydrolysis of the unstable linkages of
some acidic groups present in the lignin in this grass.