Effects on DPPH inhibition of egg‐white protein polypeptides treated by pulsed electric field technology

Abstract BACKGROUND Egg‐white protein polypeptides are potentially used as a functional ingredient in food products. In this study, the effects on DPPH inhibition of egg‐white protein polypeptides ranging from 10 to 30 kDa treated by pulsed electric field ( PEF ) technology were investigated . RESULTS 2, 2‐Diphenyl‐1‐picrylhydrazyl ( DPPH ) inhibition (%) was used to evaluate the antioxidant activity of polypeptides. In order to develop and optimize a pulsed electric field ( PEF ) mathematical model for improving the antioxidant activity, we have investigated three variables, including concentration (6, 8 and 10 mg mL −1 ), electric field intensity (10, 20 and 30 kV cm −1 ) and pulse frequency (2000, 2350 and 2700 Hz) and subsequently optimized them by response surface methodology ( RSM ). The concentration (8 mg mL −1 ), electric field intensity (10 kV cm −1 ) and pulse frequency (2000 Hz) were found to be the optimal conditions under which the DPPH inhibition increased 28.44%, compared to the sample without PEF treatment. Both near‐infrared spectroscopy ( NIR ) and mid‐infrared spectroscopy ( MIR ) were used to analyze the change of functional groups © 2012 Society of Chemical Industry . CONCLUSION The results showed that PEF technology could improve the antioxidant activity of antioxidant polypeptides from egg‐white protein under the optimized conditions .