Evaluation the effect of microwave pretreatment on the antioxidant properties of flaxseed protein hydrolysate

In this study, the effect of microwave pretreatment at the power of 500 and 900 W on the antioxidant properties (DPPH radical scavenging activity and total antioxidant capacity) of flaxseed protein hydrolysate was investigated in the period of 30-210 minutes. In the next step, the effect of different concentrations (20-100 mg/ml) of the optimum treatment on the antioxidant properties (total antioxidant capacity, Fe reducing power, DPPH radical scavenging activity and Fe chelating activity) was investigated and was compared with the antioxidant capacity of vitamin C as a synthetic antioxidant and unhydrolyzed flaxseed protein. The results showed that microwave pretreatment at a power of 500 W significantly increased the antioxidant properties (DPPH radical scavenging activity and total antioxidant capacity) of flaxseed protein hydrolysate, but higher microwave power (900 W) led to reduction of antioxidant activity in comparison to the sample without pretreatment or the sample with microwave pretreatment with a power of 500 W. The sample with microwave pretreatment with a power of 500 W and hydrolysis time of 180 minutes was selected as the optimum treatment with the highest total antioxidant capacity and DPPH radical scavenging activity. Investigating the effect of concentration on the antioxidant properties of hydrolyzed protein showed that the highest DPPH radical scavenging activity (52.7 %), total antioxidant capacity (1.35 absorbance at 695 nm), Fe reducing power (0.859 absorbance at 700 nm) were achieved at the concentration of 60 (mg/ml) and the highest Fe chelating activity (50.83%) was obtained at the concentration of 80 (mg/ml). As a result, the flaxseed protein hydrolysate with considerable antioxidant capacity, can be used in the production of functional food products, nutritional supplements for athletes and the elderly.