Comparative studies on the physico-chemical properties of hemicelluloses obtained by DEAE-cellulose-52 chromatography from sugarcane bagasse

Water- and alkali-soluble hemicelluloses isolated from dewaxed sugarcane bagasse were sub-fractionated on DEAE-cellulose-52 chromatography and obtained six hemicellulosic sub-fractions by eluting with water, 0.1 M and 0.3 M NaCl aqueous solution, respectively. Sugar composition and molecular weight analysis revealed that the lower molecular weight (14,180–43,590 g mol−1) and more branches of hemicelluloses could be extracted by the hot water, which are rich in glucose, galactose, and xylose, while the higher molecular weight (75,430–138,170 g mol−1) and more linear hemicelluloses were able to be dissolved into 1% NaOH aqueous solution, which are rich in xylose, principally resulting from l-arabino-(4-O-methyl-glucurono)-d-xylans. In addition, it was found that with increasing the concentration of NaCl (aqueous), the hemicellulosic sub-fractions with both higher arabinose to xylose ratio and higher molecular weight were eluted. Based on the FT-IR, sugar composition and 1H and 13C NMR comparative studies, the alkali-soluble hemicellulosic sub-fractions had a classical structure, with a backbone of β-(1→4)-linked xylosyl residue substituted with arabinose at C–2 and/or C–3 of main chain, whereas the difference may occur in the distribution of branches along the xylan backbone.