摘要：Pentosans, which are the main non-starch polysaccharides of wheat kernel can be separated in to water-soluble and water-insoluble fractions. Arabinoxylans and arabinogalactans are the fundamental constituents of both. Arabinoxylans have a backbone of (1-4)-linked β-D-xylopyranosyl residues, which may be un-, mono-, or di-substituted with terminal α-L arabinofuranosyl residues. Arabinogalactans have a branch structure with β-D-galactopyranosyl residues linked through (1-3) and (1-6) glycosidic bonds and terminal α-L arabinofuranosyl residues. When compared with arabinoxylans, arabinogalactans have a higher ratio of galactose and lower ratio of xylose. Arabinose and xylose is the main constituent of water insoluble pentosans. Arabinoxylans form an average 60% of them. Arabinose to xylose ratio of water insoluble pentosans is higher than water soluble pentosans. Therefore they have higher branched structure, molecular weight and water binding capacity than water-extractable pentosans.
