Abstract: In the present study, corn antioxidant peptide was desalted using a nanofiltration membrane with molecular mass cut-off of 150 Da. The desalting process was evaluated with respect to membrane flux, conductivity, Na+ concentration, desalting efficiency and antioxidant of nanofiltration product, and the protective effect of the desalted peptide on H2O2-induced oxidative damage in Caco-2 cell model was determined. The results showed that the desalination conditions were as follows: pressure 20 bar, frequency 50 Hz, temperature 20 ℃, number of nanofiltration cycles 5, and volumetric concentration factor in each nanofiltration 2. Under these conditions, the desalting efficiency was 70.73%, and the recovery of short peptide was 96.73%. Compared to that before nanofiltration, the conductivity was decreased by 33.86%, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical scavenging capacities were increased by 21.55% and 35.93%, respectively, while the ferrous ion chelating capacity was reduced by 7.38%. The desalted corn peptides at 75 μg/mL remarkably increased the viability of H2O2-induced Caco-2 cells by increasing the activity of cellular antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase, and γ-glutamylcysteine synthetase).

Key words: corn peptide; nanofiltration; conductivity; desalting efficiency; oxidative injury