The glutenin macropolymer (GMP), which is an important component of the glutenin protein in wheat flour, plays a prominent role in governing dough properties and breadmaking quality. This study investigated the changes in GMP properties during the mixing and resting stages of dough processing. The results show that the GMP content decreases by about 20.20% when the mixing time increases from 3 to 5 min, while increasing the resting time can lead to restoration of some GMP contents. Resting promotes greater formation of large-sized GMP particles, which is likely related to the increased disulfide bond content in the GMP during this process. In contrast, the mechanical force of mixing causes GMP depolymerization and formation of smaller particles. Furthermore, after mixing, the protein secondary structure tends to be disordered, the protein morphology becomes irregular, and the protein subunit ratio changes. Thus, mixing has many of the opposite effects to resting, although resting can (to some extent) restore the properties of the GMP after mixing. However, excessive resting time can lead to negative results, reflected in lower disulfide bond (SS) and GMP contents, and more irregular particle sizes. The presented results suggest that dough mixing induces rearrangement of the dough’s protein structure, and resting somewhat restores the chemical bonds and internal protein structure.

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BACKGROUND Phenolic acids are antioxidant nutrients in cereals and affect the quality of wheat products and the properties of gluten protein. Gallic acid (GA), caffeic acid (CA), syringic acid (SA), and p‐coumaric acid (p‐CA) were selected to study the interaction mechanism between cereal phenolic acids and gluten protein. RESULTS The results showed that adding GA significantly (P < 0.05) decreased the content of free sulfhydryl in gluten proteins by 70–87.26% compared with the control group. The aggregates’ behavior of gluten protein induced by adding the phenolic acids would produce oversized particles (>5000 nm). Adding the selected phenolic acids changed the hydrogen‐bond linkage of protein secondary structure. Zeta potential values of gluten protein increased significantly (P < 0.05) by 14.41%, 26.49%, 30.77%, and 57.93% for CA, p‐CA, GA, and SA respectively added at 0.03 g kg−1. Moreover, the gluten protein surface hydrophobicity increased when the phenolic acids were added at 0.03 g kg−1, displaying the effect of the phenolic acid on the hydrophobic interaction of protein. Molecular docking results showed that the selected phenolic acids could interact with glutenin and gliadin using hydrogen‐bond formation, and SA had the strongest binding with glutenin and gliadin. CONCLUSION The results demonstrated that the selected phenolic acids could interact with gluten protein via covalent cross‐linking as well as by hydrogen bonding, thereby changing the structure of the gluten protein. This exploration is expected to provide theoretical support for the development and utilization of whole‐grain foods. © 2022 Society of Chemical Industry.

Proteins have been extensively studied for their outstanding functional properties, while polyphenols have been shown to possess biological activities such as antioxidant properties. There is increasing clarity about the enhanced functional properties as well as the potential application prospects for the polyphenol–protein complexes with antioxidant properties. It is both a means of protein modification to provide enhanced antioxidant capacity and a way to deliver or protect polyphenols from degradation. This review shows that polyphenol–protein complexes could be formed via non-covalent or covalent interactions. The methods to assess the complex’s antioxidant capacity, including scavenging free radicals and preventing lipid peroxidation, are summarized. The combination mode, the type of protein or polyphenol, and the external conditions will be the factors affecting the antioxidant properties of the complexes. There are several food systems that can benefit from the enhanced antioxidant properties of polyphenol–protein complexes, including emulsions, gels, packaging films, and bioactive substance delivery systems. Further validation of the cellular and in vivo safety of the complexes and further expansion of the types and sources of proteins and polyphenols for forming complexes are urgently needed to be addressed. The review will provide effective information for expanding applications of proteins and polyphenols in the food industry.

In this study, composite nanofiber films comprising polyvinyl alcohol, wheat gluten, and glucose (PWG) were fabricated using electrospinning, followed by cross-linking via the Maillard cross-linking. Various mass concentrations of ferulic acid (FA) were incorporated into the PWG films. The results indicate that the average diameter of the FA-PWG films decreased from 449 nm to 331 nm as the concentration of FA increased, until reaching a concentration of 12%, after which a significant increase in diameter was observed. Subsequent Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results suggested that FA was distributed in the sample films in an amorphous form through hydrogen and ester bonds. Additionally, release experiments and antimicrobial tests on FA-PWG sample films showed good con-trolled release of FA and excellent anti-Escherichia coli and Staphylococcus aureus activity of this film. These findings all indicate that the FA-PWG nanofiber film is a potential candidate for food active packaging.