Water-extractable Arabinoxylan from Pearled Flours of Wheat, Barley, Rye and Triticale. Evidence for the Presence of Ferulic Acid Dimers and their Involvement in Gel Formation

Abstract

Cereal grains from wheat, barley, triticale and rye were pearled and milled. Part of the flours were treated in boiling aqueous ethanol and both the ethanol-treated and untreated flours were extracted with water. Yields of arabinoxylan in the extracts were higher for the untreated flours. Chemical, physico-chemical and structural studies showed differences between the arabinoxylans in extracts of the different cereals although arabinoxylans extracted from untreated and the corresponding ethanol treated flours were similar in neutral sugar content and patterns of substitution. Analyses showed that low amounts of ferulic acid dimers (8-O-4′, 8-5′, and 5-5′ forms) were present in all the extracted arabinoxylans. Oxidative gelation studies, using peroxidase/H₂O₂, revealed significant differences in the capacity of extracted arabinoxylans to form gels via intermolecular cross-linking. The values of elastic modulus (G′) of gels from the arabinoxylan extract of ethanol-treated flours varied from 2 to 40 Pa and were higher than those obtained from the untreated flours (0·2–6 Pa).