Optimization of Ultrasonic Assisted Extraction of Tea Polyphenols from Wuyi Rock Tea Stem

Wuyi rock tea stem as raw material,ultrasonic extraction process by response surface method was optimized. Taking the content of tea polyphenols in tea soup and sensory evaluation as the index,the technological parameters ultrasonic power,extraction temperature,extraction time and water/tea ratio were studied. The results showed that the optimum extraction parameters were as follows:Ultrasonic power 450 W,extraction temperature 73.7 ℃,extraction time 37.5 min and water/tea ratio 22:1 mL/g. The tea polyphenols content predicted by the experimental model was 15.52%,and the actual content was 15.46%±0.03%.It predicted that the process was feasible,while the tea soup had the best sensory quality and the tea polyphenols were retained to the maximum extent.