Effect of pretreatment on the antioxidant activities of walnut peptides

Walnut is an important forestry product. The peptides hydrolyzed from walnut protein have the antioxidant activities. In this study, the effect of pretreatment on the yield and antioxidant activities of the walnut peptides hydrolyzed from the defatted walnut protein powder was investigated. The results showed that pretreatment such as heat, microwave, ultrasonic wave, and alkali extracting to the low temperature -defatted walnut protein powder could increase the yield and antioxidant activities of the walnut peptides. In addition, the yield and antioxidant activities of the walnut peptides pretreated with alkali extracting and microwave were 0.85 ±0.01, 32.55% and 0.86 ±0.03, 34.63% , respectively. It was significantly higher than that of the peptides without pretreatment (0.72±0.08, 18.46% ) (p<0.05) . However, as to the high temperature -defatted walnut protein powder, there was no significant difference between the peptides with or without pretreatment.