Tetrapeptide Asp-Arg-Glu-Leu (DREL) was isolated from Jiuzao protein hydrolysates (JPHs) by alkaline proteinase (AP) and exhibited antioxidant activity by HepG2 cell model in the previous study. In this study, hydrolysis...

Two tripeptides with ACE inhibitory activity were isolated from Jiupei (the raw material of Baijiu) distillation.

Peptide Ala‐Tyr‐Ile (AYI) was isolated from Jiuzao protein hydrolysates and proved with antioxidant ability in vitro in the previous study. Considering the limitation in vitro, the antioxidant activity and potential mechanism in vivo of AYI were investigated by AAPH‐induced oxidative stress Sprague–Dawley (SD) rat model in this study. The results showed that AYI could activate Nrf2/Keap1‐p38/PI3K‐MafK signaling pathway both on gene and protein expressions. Meanwhile, AYI could markedly (p < .05) increase downstream antioxidant enzymes (i.e., CAT, GPx, SOD, and HO‐1) expressions and suppress the expressions of inflammatory factors (i.e., TNF‐α, IL‐1β, IL‐6, and NO). The results above indicated potential antioxidant and anti‐inflammatory activity in vivo of peptide AYI. In addition, AYI could also exist stably in baijiu after 14‐day storage. This study provides a better thought for the use of Jiuzao to isolate antioxidant peptides and enhance baijiu antioxidant function by adding these peptides in it. Practical applications Jiuzao is a by‐product of baijiu distillation, which is generally used as the forage of livestock. However, considering the raw material of baijiu distillation, nonvolatile components remain in Jiuzao, such as protein and peptides. Therefore, functional peptides can be extracted from Jiuzao. Peptide AYI was identified from Jiuzao protein hydrolysates and was proved with antioxidant ability in vitro. This study further explored its antioxidant capacity in vivo and proved it could be used as a natural ingredient for baijiu to enhance its antioxidant function. It can also contribute to pharmaceutical, cosmetic, and functional foods industry. In addition, other functional components in Jiuzao also deserve for exploring.