Interactions between dietary fiber and ferulic acid changed the aggregation of gluten in a whole wheat model system

As the main phenolic acid in wheat bran, ferulic acid (FA) may impact the reactions between disulfide bonds (SS) and sulfhydryl groups (SH) to change gluten proteins aggregation. This study investigated effects of dietary fiber (DF) and FA on secondary structures, thermal properties, and microstructures of gluten proteins. Results showed that the major portion of gluten secondary structures in all test groups was β-sheets (3583-4498 cm2/m2) while α-helices (869-1628 cm2/m2) made up only a small part. The group with 20 g/kg FA and 60 g/kg DF had a similar β-sheet content (4462 cm2/m2) as the control group (4408 cm2/m2), which decreased the damage of gluten structures induced by FA or DF. The total equivalent thiol (SHeq) content, SS content, denaturation temperature (Tp), and enthalpy (△H) of gluten proteins were significantly decreased (P < .05) compared with the control group when DF or FA increased. DF and FA addition also led to a more disordered gluten network shown by scanning electron microscopy (SEM). When DF and FA were added together, the interaction between DF and FA prevented the SS decrease. However, thermal properties analysis of groups including different contents of FA and DF indicated that stability was not improved as expected.