Molecular characterization of water-extractable arabinoxylan from wheat bran and its effect on the heat-induced polymerization of gluten and steamed bread quality

Enhanced bread quality by water-extractable arabinoxylan (WEAX) depends on its inherent structural features. To clarify the underlying mechanism, the current study prepared WEAX with varied structures via graded ethanol precipitation from wheat bran, and their effects on the steamed bread quality in relation to the heat-induced physicochemical changes of dough components were evaluated. The results showed that WEAX with a lower molecular weight (Mw), higher branched degree and ferulic acid content possessed a superior improved effect on the steamed bread quality. The gelatinization of starch was partially inhibited by WEAX, with a more distinct effect by the lower Mw and higher branched WEAX. However, WEAX suppressed the short-term retrogradation of starch, especially for the higher Mw and lower branched WEAX. Both of the heat-induced polymerization degree and rate of gluten were reduced by WEAX, and these reductions were more evident by the lower Mw and higher branched WEAX. The partial inhibition of gluten polymerization by WEAX contributed substantially to the enlarged loaf volume and softer textural property of steamed bread. The current study can provide a theoretical basis for the exploitation of WEAX as a nutritious and technofunctional dough improver.