Effect of solid-state fermentation on the release and antioxidant activity of soluble polyphenols from wheat bran

Using wheat bran as substrate, four solid-state fermentation methods were compared for soluble polyphenol release. The effect of Bio-enzymatic synergy (BES) is the most significant, producing 4.85 mg GAE/g of total phenolic substances, which is 45.77% higher than the control group (CK). LC-MS analysis revealed that ferulamide and 2,4,6-trihydroxybenzoic acid predominated in positive ion mode, while salicylic acid dominated in negative mode. Notably, salicylic acid was found almost exclusively in ester-bound and glycoside-bound fractions (>88%), indicating its release requires cleavage of covalent linkages to cell wall components. The release of salicylic acid results from the synergistic action of Bio-enzymatic synergy and alkaline hydrolysis. Both in vitro and in vivo assays confirmed that BES-released polyphenols enhanced antioxidant activity, reducing ROS and MDA levels while increasing GSH-Px activity and extending C. elegans lifespan. These findings provide a mechanistic basis for developing targeted fermentation-enzymatic processes to produce functional wheat bran extracts.