Determination of Optimum Conditions for the Production of Peptides with Antioxidant and Nitric-Oxide Inhibition Properties from Protein Hydrolysis of Pumpkin Seed Meals Using Pepsin Enzyme

Background and Objectives: In this study, hydrolysis condition optimization of the pumpkin (Cucurbita pepo) seed proteins was carried out achieve maximum DPPH radical scavenging and nitric-oxide inhibition properties using Design Expert Software and response surface methodology.  Materials & Methods: In general, 1–3% concentrations of pepsin enzyme, 30–40 °C temperature and 120–100 min time were selected as the independent variables. Results: Results showed that the optimum conditions for achieving maximum DPPH radical scavenging and nitric-oxide inhibition activities included temperature of 32 °C, time of 161.5 min and an enzyme-substrate ratio of 3% with antioxidant and nitric-oxide inhibitory activities of 54.63 and 89.09%, respectively. These results were largely similar to the results suggested by the software (56.03 and 91.92%, respectively). Conclusion: Based on the results, hydrolyzed proteins of the pumpkin seeds include good antioxidant and nitric-oxide inhibitory activities and can therefore be used as natural compounds for replacing synthetic preservatives in food products.