Technological Experiments on Ultrasound Assisted Extraction Tea-polyphenols from Tea Fresh Leaves

According to the lack of rural labor force in China nowadays,tea-picking by machines has gradually become the main form of tea harvest.In order to improve the value of tea picking by machines and reduce the processing costs,the technology and methods of extracting the fresh leaf are studied.This experiment used fresh leaves of tea as raw material,the water as solvent and ultrasonic wave as an assisted way to extract tea-polyphenols in fresh leaves of tea.The effect of different ultrasonic wave output power,granularity,extraction temperature and ratio of solid—liquid on extracting tea polyphenols is studied.Based on the single factor experiment,optimized process parameter,primary and secondary factors of the extraction are determined by L9(34) orthogonal experimental design.The optimal extraction process parameters by the experimental results were: extraction solid-liquid ratio is 1:20,extraction temperature is 60℃,extraction ultrasonic-wave power is 350W,and tea smashing granularity is 1.5mm,meanwhile,in which tea-polyphenols raises rate is 23.88%.Compared to the water bath extraction method,extraction rate of tea-polyphenols is higher,using time is shorter and extracting times is few than the conventional by the ultrasonic wave.And the quantities of extracting tea polyphenols are the same as the dried tea.Thus it can be seen extracting tea polyphenols in the fresh leaves using ultrasound is feasible.