pH-controlled acetic acid pretreatment for coproduction of low degree of polymerization xylo-oligosaccharides and glucose from corncobs.

Acetic acid (HAc) pretreatment has been widely used for the production of xylo-oligosaccharides (XOS), requiring harsh reaction conditions because XOS are intermediates during the xylan degradation process. This complexity makes the pretreatment process difficult to regulate. In this study, a pH-controlled HAc pretreatment using sodium hydroxide (NaOH) was proposed to enhance the yield of XOS and to reduce its degree of polymerization (DP) from corncobs (CC). By employing this method (0.3 M-2.7), 49.7 % of XOS with DP 2-6 was obtained, alongside a notable increase in the fraction of XOS with DP 2-4 (10.1 g/L). This performance significantly surpassed that of the HAc alone (0.3 M). Moreover, the glucose yield from CC via pH-controlled HAc pretreatment was as high as 93.1 % after 72-h enzymatic hydrolysis. These results suggested that the pH-controlled HAc pretreatment could be a promising strategy for the coproduction of low-DP XOS and fermentable sugars.