Fig. 2

The chemical structures of xylan from different sources. Xylan consists of the backbone chain of xylose units joined by β-1,4-glycosidic bond, and substituted by α-arabinofuranosyl residues at second or third carbon (C2-O- and/or C3-O-). The xylan backbone chain extension from the non-reducing end is represented by R and extension from reducing ends are represented by R1. The wheat arabinoxylan used in the current study was highly substituted as indicated in a and oat arabinoxylan had lesser substitution as indicated in b. Glucuronoxylan consists backbone of xylose units β-1,4-d-glycosidic bond that is substituted with 4-O-methyl-α-d-glucopyranosyl uronate residues. Beechwood xylan used in the current study consisted mostly of glucuronoxylan as indicated in c