Structure and rheological behaviour of arabinoxylans from Canadian bread wheat flours

Abstract

Water-soluble arabinoxylans from 10 flours of eight different varieties of the Canada western red spring (CWRS) wheat class (Neepawa, Katepwa, Roblin, Columbus, Benito, Lauro, Lancer, and Selkirk) were isolated and purified. Chemical analyses indicated only a small variation in the degree of branching among arabinoxylans; arabinose to xylose ratios ranged from 0.62 to 0.68. In contrast, substantial differences were found in the content of ferulic acid (0.93 to 1.52 mg/g), molecular size distribution, and in molecular weight (134,700-201,600) of the 10 arabinoxylan preparations. Oxidative gelation studies (using H202peroxidase) revealed significant differences in the capacity of these polymers to form gels via intermolecular cross-linking. The values of elastic modulus, G’, of arabinoxylan gels (10 g/L) varied from 5.8 Pa to 43.0 Pa. The high molecular weight arabinoxylans formed more rigid gels at low polymer concentration than did their low molecular weight counterparts. In addition to molecular weight, the ferulic acid content was an important determinant of gel network rigidity. © 1994 Academic Press, Inc.