Green and chemical-free process of enzymatic xylooligosaccharide production from corncob: Enhancement of the yields using a strategy of lignocellulosic destructuration by ultra-high pressure pretreatment

•UHP enhances lignocellulosic destructuration and enzymatic hydrolysis of corncob.•UHP caused significant differences in XOS yields between native and pretreated corncob.•UHP at 100 MPa significantly improved the accessibility of endo-xylanase.•UHP pretreatment at 100 MPa relatively did not affect composition of corncob.

In this study, the pressures at 50-500 MPa were evaluated at different time to pretreat and further enzyme hydrolysis. The ultra-high pressure (UHP) pretreatment at 100 MPa for 10 min led to improved accessibility of enzyme for conversion of xylan to xylooligosaccharide (XOS). The maximum XOS yield of 35.6 mg/g substrate was achieved and firstly reported at 10% (w/v) of substrate, 100 U of endo-xylanase/g corncobs and incubation time of 18 h. The enzymatic hydrolysis efficiency was increased by 180.3% and released a high amount of xylobiose. The UHP pretreatment relatively did not affect to the composition of corncob, but decreased 34.3% of lignin. Interestingly, antioxidant activities of XOS using UHP pretreatment were higher than untreated corncob. The UHP pretreatment improved lignocellulosic destructuration and XOS yields in a shorter time without the need of chemicals, implying that UHP could be an effective pretreatment of biomass with a chemical-free process.

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