Effect of fermentation on structural properties and antioxidant activity of wheat gluten by Bacillus subtilis

Abstract

<i>Bacillus subtilis</i> has been extensively studied for its ability to inhibit the growth of harmful microorganisms and its high protease activity. In this study, <i>Bacillus subtilis</i> was used to ferment gluten and assess the effects of the fermentation process on the physicochemical, microstructure and antioxidant properties of gluten. The results of Fourier infrared spectroscopy (FT-IR) and circular chromatography (CD) showed a significant decrease in the content of α-helix structures and a significant increase in the content of β-sheet structures in gluten after fermentation (<i>p</i> < 0.05). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that glutenin was degraded into small molecular peptides with a molecular weight of less than 26 kDa after 24 h of fermentation; meanwhile, the fermentation process significantly increased the free amino acid content of the samples (<i>p</i> < 0.05), reaching 1923.38 μg/mL at 120 h of fermentation, which was 39.46 times higher than that at 24 h of fermentation (<i>p</i> < 0.05). In addition, the fermented back gluten has higher free radical scavenging activity and iron reduction capacity. Therefore, fermented gluten may be used as a functional food to alleviate oxidative stress. This study provides a reference for the high-value application of gluten.