Effect of ultrasonic pretreatment on the antioxidant properties of porcine liver protein hydrolysates

Summary In this study, the effect of ultrasonic pretreatment on the antioxidant activity of porcine liver protein hydrolysates ( PLPH s) was investigated. The results showed that the degree of hydrolysis ( DH ) and peptide contents of the PLPH s increased as the time of ultrasonication increased. The hydrolysate pretreated with ultrasonication for 60 s exhibited the highest DH and peptide contents. The hydrolysate pretreated with ultrasonication for 45 s exhibited the highest ferrous ion chelating ability and reducing power. The hydrolysate pretreated with ultrasonication for 30 s exhibited the highest 2,2‐diphenyl‐1‐picrylhydrazyl ( DPPH ) radical scavenging activity and the higher inhibitory activity in the linoleic acid autoxidation system. The molecular weight of peptides in the hydrolysates was less than 6.2 kD a. The results clearly demonstrated that ultrasonic pretreatment enhances the antioxidant activities of the PLPH s in a short period of time (15–30 s).