Comparison of different techniques for extraction tea-polyphenols from tea leaves

The extraction techniques and determination methods of tea-polyphenols were studied.The amounts of tea-polyphenols from tea leaves were determined by HPLC and three extraction methods(warm soakage,ultrasonic extraction and Soxhlet extraction) were used after crushing samples under liquid nitrogen.The results shown that the extraction amount of tea-polyphenols was the largest by ultrasonic extraction.The ultrasonic extraction is simple and rapid and is suitable for the determination of polyphenols in green tea.