Objective To investigate the inhibitory effects of enzymatic hydrolysates from different distiller's grain proteins on xanthine oxidase (XOD) activity, providing a theoretical basis and technical support for the development of XOD inhibitory peptides from distiller's grains.

Methods Using Hongqu distiller's grains (HDG) and sauce-flavor Baijiu distiller's grains (BDG) as raw materials, alkaline protease was used as the hydrolytic enzyme. The protein hydrolysis rate, XOD inhibitory activity of the hydrolysates, and their tolerance to simulated gastrointestinal digestion were compared. The optimal distiller's grain source was selected for enzymatic hydrolysis process optimization.

Results 1) The enzymatic hydrolysates of both HDG and BDG exhibited XOD inhibitory activity. BDG had a higher protein hydrolysis rate (56.28±0.01)% and stronger XOD inhibitory activity, with a half-maximal inhibitory concentration (IC₅₀) of (7.73±0.26) mg·mL⁻¹, showing significant differences compared to HDG (P＜0.01). 2) After gastrointestinal digestion, the XOD inhibitory activity retention rates of the hydrolysates from both distiller's grains were above 31%, with no significant difference between them (P＞0.05). 3) The optimized enzymatic hydrolysis conditions for BDG were: alkaline protease dosage of 6000 U·g⁻¹, temperature of 50℃, pH 9.5, and time of 5 h. Under these conditions, the protein hydrolysis rate was 58.00%, and the IC₅₀ of the hydrolysates for XOD inhibition was 5.54 mg·mL⁻¹.

Conclusion The enzymatic hydrolysates of sauce-flavor Baijiu distiller's grains (BDG) exhibit good XOD inhibitory activity. BDG is a promising protein source for the preparation of XOD inhibitory peptides.