Hydrolysis of rapeseed meal protein under simulated duodenum digestion: Kinetic modeling and antioxidant activity

• Antioxidant peptides from rapeseed meal simulated duodenal digestion were examined.
• Best hydrolysis obtained at 10 g/L trypsin, 4 g/L substrate, 40 min hydrolysis.
• Enzyme and substrate amounts and time used to establish kinetic hydrolysis model.
• Antioxidant free amino acids increased after hydrolysis.
• Peptides of MW 1–1.5 kDa are effective in scavenging DPPH and binding iron.

Kinetics modelling, DPPH radical scavenging activity and reducing power of rapeseed meal protein were investigated under simulated duodenum digestion. Kinetics of the reaction was considered in relation to initial substrate concentration, initial enzyme concentration, and hydrolysis time. Optimum hydrolysis conditions were trypsin concentration of 10 g/L, substrate concentration of 4 g/L, time of 40 min and temperature of 37 °C. From the results a general kinetic enzymolysis equation was suggested, providing a rational theoretical basis for determining the parameters of the reaction. The highest antioxidant activity was in accordance with the optimum reaction conditions. Antioxidant free amino acids increased after hydrolysis. Antioxidant oligopeptides of molecular weights of 2608, 1695 and 211 Da were identified. At a concentration of 2 mg/mL, the peptide fraction of CS-F2-CC2; with molecular weight of 1000–1500 Da; showed the highest DPPH radical scavenging activity and reducing power, accounting for 70.32% and 0.538, respectively. The trypsin-hydrolysate displayed a potential capacity to scavenge free radicals and binding irons after duodenal digestion, appearing as promising ingredient to formulate functional foods with antioxidant activity.