The Effect of Fermentation with Saccharomyces cerevisiae on the Release of Bound Phenolic Compounds from Wheat Bran and Its Effect on Antioxidant Capacity

Wheat bran (WB) is a rich source of phenolic compounds (PCs) with antioxidant capacity (AOX). Approximately 90% of these PCs are bound to the cell wall matrix, which limits their bioavailability. Fermentation with Saccharomyces cerevisiae is an effective strategy to release these bound phenolics. This study aimed to evaluate the effect of fermentation on the release of bound PCs in WB and their AOX during an in vitro digestion system. WB was fermented with Saccharomyces cerevisiae for 2, 4, and 6 days and subsequently subjected to simulated digestion. Free PCs were extracted with methanol, while bound PCs were obtained through alkaline hydrolysis. Total PCs were quantified using the Folin–Ciocalteu method, and AOX was assessed through DPPH, TEAC, and FRAP assays. The content of bound PCs significantly increased after fermentation (p < 0.05): 30.24 ± 0.06 mg GAE/g (day 2), 27.18 ± 0.40 mg GAE/g (day 4), and 28.41 ± 0.40 mg GAE/g (day 6), compared with unfermented WB (7.7 ± 0.21 mg GAE/g) (p < 0.05). AOX was notably enhanced; DPPH reached its peak on day 4 (47.38 ± 0.07 µmol TE/g) (p < 0.05). TEAC was highest on day 2 (26.20 ± 0.43 µmol TE/g) compared with the control (20.14 ± 0.22 µmol TE/g) (p < 0.05) and FRAP showed a slight improvement on day 6 (57.38 ± 0.10 µmol TE/g) relative to the control (56.22 ± 0.13 µmol TE/g) (p < 0.05). Fermentation with Saccharomyces cerevisiae promotes the release of bound PCs in WB and enhances its AOX, highlighting its potential as a functional food ingredient.