Study on the extraction and antioxidant properties of flavonoids from onion

The optimum extraction conditions and antioxidant activity of flavonoids from onion were studied. The effects of ethanol concentration, liquid-material ratio, ultrasonic power, ultrasonic time and extraction temperature on extraction rate were analyzed by single factor experiment in the extraction process. Based on the above, the optimum process conditions of onion flavonoids extraction were obtained by orthogonal experiment, namely the ethanol concentration 60%, liquid ratio 1:25, ultrasonic power 90 W, ultrasonic time 30 min, extraction temperature 40 °C, including 5.27 mg/g of flavone yield under the condition of the onion medium. In vitro antioxidant experiments showed that onion flavonoids had a strong reduction force, intense scavenging ability for hydroxyl radical and superoxide anion radical, and more violent antioxidant activity in vitro than BHT at the same concentration.