Study on Ultrasonic Extraction Technology and Oxidation Resistance of Total Flavonoids from Peanut Hull

In this article, a method of ultrasonic extraction (USE) was used to extract flavonoids from peanut hulls. Orthogonal array design experiment was employed to get the optimum extraction conditions. The optimum USE conditions were as follows: ethanol concentration was 65%; solid/liquid ratio (g mL-1) was 1:65; temperature was 60°C; ultrasonic frequency was 45 Hz; ultrasonic power was 150 W; initial pH of feed liquid was 6.0; time for extraction was 3 h. The optimum extraction yield of flavonoids was 8.23 mg g-1. The antioxidant activity of the crude extract was tested with phosphomolybdenum complex method, the reduction of K3Fe(CN)6 and DPPH assay. The IC50 value for DPPH radical scavenging lied 14.86 μg ml-1, and 28 μg mL-1 of PHF exhibited total antioxidant activity and reducing power which were comparable to that of the ascorbic acid standard at 52.41 and 15.41 μg mL-1, respectively.