Effects of Different Pretreatment Methods on the Enzymatic Hydrolysis of Cassava Residue

The enzymatic hydrolysis of cassava residue treated by a hot water (HW) pretreatment, an extreme-low acid (ELA) pretreatment, and an alkaline hydrogen peroxide (AHP) pretreatment was investigated. The results showed that the ELA pretreatment dissolved greater xylan and glucose quantities than the HW pretreatment under the same conditions, and the xylan and glucan contents of the pretreated substrate affected the subsequent cellulase hydrolysis. The conversion to glucose by cellulase hydrolysis reached 81.4% after the HW pretreatment, while the glucose yields under the ELA and AHP pretreatment conditions were 78.3% and 71.0%, respectively. In addition, supplementation with xylanase improved cellulase efficiency. At an equal xylanase dosage, a higher glucose yield (i.e., 91.3%) was achieved for the ELA-pretreated substrates that contained a lower xylan content. Xylanase supplementation in the AHP pretreatment had little effect on the glucose conversion. Finally, X-ray diffraction studies showed that the HW and ELA pretreatments increased the cassava residue crystallinity, while the AHP pretreatment had little effect.