Cereal Chem. 70:641-646   |  VIEW ARTICLE

Structural Heterogeneity of Wheat Endosperm Arabinoxylans.

M. S. Izydorczyk and C. G. Biliaderis. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

Water-soluble arabinoxylans from flours of 10 cultivars belonging to five classes of Canadian wheat were isolated and purified. Fractionation of arabinoxylans by a graded (NH[4])[2]SO[4] technique gave three fractions: F65, F75, and F100. The numbers refer to the saturation level of the salt at which precipitation occurred. The yield of F65 was 53.3-85.9% of the total material recovered; F75 accounted for 10.2-35.7%; and F100 was only 3.9-11.0%. F65 showed the highest viscosity (3.15-5.24 dl/g). Viscosity decreased in F75 (2.23-3.60 dl/g) and F100 (0.88-1.21 dl/g). Ferulic acid was confined mostly to F65. The xylose-to- arabinose ratio was the highest for F65 (2.23-1.53) and much lower for F75 and F100 (1.22-1.05 and 1.18- 1.03, respectively). F65 was a high molecular mass arabinoxylan fraction with the highest amount of xyloses carrying only one arabinose side chain residue (at C-2 or C-3), but it had the lowest content of xylose residues substituted with arabinoses at both C-2 and C-3. F75 and F100, with decreasing molecular mass of arabinoxylan fractions, had a decreased amount of singly substituted xyloses but an increased amount of doubly branched xyloses. The occurrence of unsubstituted Xylp residues was much higher in the high molecular mass arabinoxylan fractions. The short Araf side chains were more commonly encountered in low molecular mass arabinoxylan fractions.