Extraction Process and Antioxidant Activity of Tannins of Quercus Liaotungensis Valonia

Based on the valonias of Quercus Liaotungensis from Diantou forest farm,the process of ultrasonic-assisted extraction of tannins was optimized by employing the response surface methodology(RSM),the total antioxidant activity and the ability to scavenge free radical DPPH· and ·OH were examined by comparing to V_C. The results showed that the optimal extraction process was obtained when using 50% of ethanol concentration at a liquid-solid ratio of 30:1 mL/g and at temperature extraction of 50℃ with power extraction of 200 W,the amount of tannins obtained under such processes was 70.152 mg/g. Through the verification experiment,the amount of tannin extracted was 70.143 mg/g. The total antioxidant activity and the ability to scavenge free radical of tannins was linearly correlated with their concentration. At a concentration of 80 mg/L,the total antioxidant activity of tannins was 25.84% lower than V_C,the DPPH· scavenge rate was 18.9% lower than V_C and ·OH was 28.6% lower. Quercus Liaotungensis valonia have certain industrial utilization value and can be used as a new antioxidant.