Effect of phytochemicals from grape seed on the improvement of noodle quality and the structure of wheat gluten

In this study, we investigated the effect of phytochemicals from grape seeds on the quality of noodles and the structural hierarchy of the gluten network. The results showed that proanthocyanidins (GSP) had the greatest effect on the color of the sheets, while gallic acid (GA) had the least impact. The cooking characteristics were most pronounced when we added GSP and GA, and the effects of all phytochemicals on the texture and tensile properties of the pasta were improved. Thermal characterization showed no change in gluten stability. Combining the results of free sulfhydryl content, protein secondary structure, and noncovalent interactions, the interactions between different phytochemicals were summarized. Specifically, GSP significantly enhanced the gluten via ionic bonding and disulfide g-g-g conformation, accompanied by a rise in α-helix. Meanwhile, catechins improved gluten mainly by enhancing hydrogen bonding, epigallocatechin gallate (EGCG) led to a significant increase in hydrophobic interactions (P < 0.05) with contributions from ionic and hydrogen bonding. Additionally, GA protein secondary structure similar to the control group, which was a result of disulfide bonding balanced with noncovalent interactions. The mechanism of interaction between the important phytochemicals and the noodles helps to better reveal the improvement effect of grape seed powder on noodles and provides a reference for the production application of grape seeds added to noodles.