Separation of xylose oligomers from autohydrolyzed Miscanthus × giganteus using centrifugal partition chromatography

Autohydrolysis of cellulosic materials for saccharification generates xylose-oligosaccharides (XOS), due to the partial hydrolysis of xylan. Developing an efficient method for the separation and recovery of XOS from the prehydrolyzates would provide an excellent opportunity for the better utilization of the cellulosic material and for value-added co-product production. In this study, we investigated the use of centrifugal partition chromatography (CPC) for the fractionation of XOS from Miscanthus × giganteus (M × G). During autohydrolysis of miscanthus biomass at 180 C for 20 min, 63% of xylan was converted into XOS and xylose. The ensuing XOS concentrate contained up to 30% of XOS, which were distributed as 15.9% xylobiose (DP2), 5.9% xylotriose, (DP3), 5.6% xylotetraose (DP4), 0.8% xylopentaose (DP5) and 0.6% xylohexaose (DP6). The XOS concentrate was further fractionated by CPC with a solvent system composed of 4:1:4 (v/v/v) butanol:methanol:water. Using CPC techniques, 230 mg (80%) of DP2 to DP6 oligomers were fractionated from 1 g of XOS concentrate. The recoveries of individual XOS were 90.2% DP2, 64.5% DP3, 71.2% DP4, 61.9% DP5 and 68.9% DP6. The purities of DP2 to DP6 fractions were 61.9%, 63.2%, 44.5%, 31.5% and 51.3%, respectively. Presence of DP2 and DP3 in the CPC purified fractions was further validated by mass spectrometry analysis. The study provided information on fast recovery of individual XOS from crude biomass prehydrolyzate.