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

Abstract

Bacillus subtilis has been extensively studied for its ability to inhibit the growth of harmful microorganisms and its high protease activity. In this study, Bacillus subtilis 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 (p < 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 (p < 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 (p < 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.

Functional and Bioactive Properties of Wheat Protein Fractions: Impact of Digestive Enzymes on Antioxidant, α-Amylase, and Angiotensin-Converting Enzyme Inhibition Potential

“…In our study, the increased content of total antioxidant compounds after TC-H suggests a higher reactivity towards the Folin–Ciocalteu reagent, possibly due to the release of active peptides and free AAs, as well as conformational rearrangements leading to a greater exposure of the antioxidant sites in the (poly)peptide chains, some of which may be mediated by protein–phenolic interactions. The trend towards increased antioxidant activity after TC-H, except for WF and prolamins, is in partial agreement with the enhanced free radical scavenging activity reported by Zhao et al [ 10 ] after the fermentation of wheat gluten by Bacillus subtilis , an important producer of alkaline proteases. Our findings of significant positive associations between the antioxidant, anti-α-amylase and anti-ACE activities of TC hydrolysates have high practical relevance.…”

“…WF protein fractions represent a rich pool of substrates that could be utilized to yield ingredients with enhanced or novel biological and functional activities, but there are limited data on their health-promoting effects. Previous reports in this area were mainly focused on wheat non-nutrient compounds [ 2 ], wheat gluten [ 10 , 11 ] or unfractionated wheat germ proteins [ 12 , 13 ]. The presence of phenolic compounds in WF, including high levels of phenolic acids [ 14 , 15 ], is noteworthy, as these compounds can interact with proteins through covalent and noncovalent binding [ 16 ], which could confer unique or modified functionalities to the conjugated proteins.…”