Utilizing brewer's spent grain as a sustainable antioxidant peptides source to enhance yeast tolerance under multiple stresses.

This study explored utilizing nitrogen sources derived from brewer's spent grain (BSG) to enhance brewer's yeast tolerance, with the aim of reducing carbon emissions in breweries and promoting BSG's value-added applications. Results demonstrated that preculture with BSG protein hydrolysates (BSGPH) and purified antioxidant peptides improved yeast tolerance to ethanol, oxidative and osmotic stresses. Specifically, both the ethanol precipitated hydrolysates (BH-95S) and its chromatographically separated G15-B fraction, exhibited superior biological activity in improving yeast physiological properties due to their low molecular weight (Mw) and high antioxidant capacity. Furthermore, the RP-HPLC purified BP-R8 fraction from G15-B with the highest ABTS scavenging activity (657.71 μM/TE), was identified to contain 417 peptides. Among these, two novel antioxidant peptides, LDWGPH and FVY, were confirmed strong in vitro and cellular antioxidant activities by molecular docking and activity assays. These findings highlight BSG's potential as a source of antioxidant peptides for improving yeast tolerance to ethanol, oxidative and osmotic stresses with promising applications.