Optimization of Ultrasonic Extraction of Polyphenols from Oolong Tea Byproducts Using Response Surface Methodology

Abstract

Oolong tea, a popular drink with beneficial health properties, is a rich source of polyphenols that have a wealth of physiological activities. Ultrasound-assisted extraction (UAE) was applied for the extraction of total polyphenols from the byproducts of oolong tea. The predicted optimal conditions for the highest concentration of polyphenols were found at temperature of 550C, time of 45 minutes, ethanol 45% v/v, solid/liquid of 1:25, tea size ¡ 1 mm by UAE method (40 kHz, sonication power 250W). Antioxidant activity of three different materials of oolong tea was IC50 = 15.69; 19.07; 12.02 g/ml, respectively; IC50 of vitamin C was 16.47 g/ml.