Antioxidant activity and inhibition of meat lipid oxidation by soy protein hydrolysates obtained with a microbial protease

Enzymatic proteolysis is helpful to release bioactive peptides encrypted in food proteins. The antioxidant capability of soy protein isolate (SPI) hydrolyzed with a novel protease preparation from Chryseobacterium sp. kr6 was investigated. The antioxidant capacity of the hydrolysates was evaluated using radical-scavenging and metal-chelating assays. Maximum values for scavenging of 2,2’-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid and 2,2-diphenyl-1-picrylhydrazyl radicals reached 88% and 78%, respectively. The Fe^2+-chelating ability of SPI hydrolysates reached higher values at 1 h hydrolysis (61%), decreasing thereafter; and the maximum reducing power was observed after 6 h hydrolysis. The SPI hydrolysates (10 mg/mL) were able to inhibit the formation of thiobarbituric acid reactive substances in pork (62% inhibition) and salmon (65% inhibition) as model systems. These hydrolysates might be applied as natural antioxidants delaying the lipid oxidation and therefore improving quality and increasing the shelf-life of food products.