Xylooligosaccharides and glucose preparation from sugarcane bagasse by a combination of acetic acid treatment and sequential xylanase and cellulase enzymatic hydrolysis

Acetic acid of 2.5-10% (m/v) can be exploited to assisted hydrolyze sugarcane bagasse for directly producing XOS, however, it simultaneously generated high amounts of byproducts, increasing the difficulty of products purification, and there are evidences that the ratio of active ingredients (xylobiose (X2) and xylotriose (X3)) was lower. In this study, a strategy of acetic acid pretreatment with post-xylanase treatment of sugarcane bagasse for preparing xylooligosaccharides (XOS) was put forward. Firstly, the acid hydrolysis with post-xylanase hydrolysis processes varied the parameters applying single-factor experiments design using the 2.5-10% (m/v) acetic acid at a temperature of 130-190 C-degrees and a duration of 20-60 min. According to single-factor experiments, a threelevel three-factor Box-Behnken Design with response surface methodology was performed to maximize the XOS yields. As a results, the maximum XOS yield was achieved at over 60.7% with a sequential operation of acid hydrolysis (3.6% acetic acid, 180 C-degrees, 35 min) and xylanase hydrolysis (12 h), and the ratio of (X2 + X3)/XOS was over 70%. Moreover, the treatment with 3.6% acetic acid and xylonase also improved enzymatic hydrolysis yield to 82.1%. Overall, favorable outcomes suggest that the combined approach of acidic and enzymatic hydrolysis is cost-effective for XOS with desired degree of polymerization and glucose preparation.