Conversion of Baijiu distillers' grains to functional peptides: Process optimization and antioxidant activity evaluation

Distiller's grains resourcing is a crucial problem for the sustainable development of the Chinese Baijiu industry. In order to improve the protein utilization of distiller's grains. In this study, distiller's grains pretreated by wet crushing combined with amylase/cellulase were further hydrolyzed with neutral protease combined with papain at 50 degrees C for 3 h. The hydrolysates were decolorized by 1% coconut shell activated carbon for 15 min, and separated and purified by macroporous resin and Sephadex gel to yield peptide fractions (F1, F2, F3 and F4). The F3 fraction with the highest radical scavenging activity was analyzed by nano-LC-MS/MS and peptidomics to identify peptides. Three peptides (especially newly discovered AAHVLAAAFL) displayed strong alcohol solubility and antioxidant activity and were stably bound to key regulatory pathway receptors (Keap1-Nrf2) and myeloperoxidase (MPO), further elucidating molecular mechanism of anti-oxidation. These findings provided knowledge for potential functional peptide candidates and facilitates the high-value commercial development of distiller's grains.