关键词: 电氧化, 茶, 还原性多酚类, 定量分析, 吸收光谱

Abstract: For the purpose of obtaining a preliminary quantitative method to analyze the reductive polyphenols in tea that are extremely unstable under normal condition. Reductive polyphenols are related to the antioxidantive activity of tea, and their determination is important for understanding the extent of chemical reaction that occurs in tea during the manufacturing process. Electrooxidation of the reductive polyphenols led to a new absorption maximum at 325 nm. The optical density difference at 325 nm of tea solution before and after electrooxidation was directly proportional to the content of reductive polyphenols, which was used to measure the content of reductive polyphenols in tea. Reproducibility and accuracy of this analytical method was not satisfactory due to the unstable nature of reductive polyphenols under normal condition. Application of this method to the several teas revealed that concentration of reductive polyphenols was high in green tea and very low in Pu-Erh tea.

Key words: electrooxidation, tea, reductive polyphenols, quantitative analyasis, absorption spectrum