Gluten aggregation behavior in gluten and gluten-starch doughs after wheat bran dietary fiber addition

The influences of wheat bran dietary fiber (WBDF) on the structural changes and aggregation behavior of gluten in both gluten (G) and gluten-starch (G + S) systems were investigated. Six WBDF levels were provided in the G and G + S system to reveal the correlations between WBDF level and gluten depolymerization behavior. Results showed that WBDF caused a significant reduction in S-S content and impaired water holding capacity, implying possible disaggregation behavior and less compact gluten network structure. The size exclusion chromatography profile also exhibited the loss of high molecular weight gluten aggregates in both G and G + S system. The Fourier transform-infrared spectroscopy results reveled an increase in beta-sheet (similar to 55%) conformation at the cost of the beta-turn structure, whereas random coils and aggregates tended to decrease. It may be speculated that the transformation of beta-turn into beta-sheet structure be responsible for the disaggregation behavior of gluten aggregates and the more rigid gluten network.