Research Of Green Tea's Chemical Composition And Antioxidant Activity

The chemical constituents of a series of green tea and its antioxidant activity are studied in this paper. The contents of tea flavonoids, and tea polysaccharide are determined by UV spectrophotometry. The contents of caffeine and tea polyphenols are determined by high performance liquid chromatography. Volatile of components of green tea are analyzed by gas chromatography - mass spectrometry (GC-MS). Antioxidant activity of a series of green tea are determined by flowing injection chemiluminescence.The contents of tea flavonoids of 12 species of green tea are extracted by ultrasonic method. Take the quercetin as a standard and the aluminum trichloride as chromogenic agent, the maximum absorption wavelength of 420.0 nm, the method coefficient of variation is less than 0.11﹪; the recovery of method is 94.44﹪- 105.6﹪; the content of flavonoids is 0.9428 - 6.598 mg / g. Take the glucose as a standard, the contents of tea polysaccharide of 12 samples of green tea are determined by concentrated sulfuric acid, phenol color method, the maximum absorption wavelength of 489.0 nm; the method coefficient of variation is less than 0.20﹪; the recovery of method is 100.4﹪- 103.0﹪; the content of polysaccharide is 57.19 - 357.8 mg / g.The contents of caffeine and tea polyphenols of 12 kinds of green tea are extracted with chloroform and ethyl acetate, are determined by HPLC. The content of caffeine is 4.637 -12.99 mg / g, in which the highest content of Fujian Green Lo. The content of tea polyphenols is 48.904 - 110.86 mg / g, in which the highest content of Zhejiang Longjing.Volatile compounds of two kinds of green tea samples are isolated and identified by GC-MS, with wet distillation extraction methods. The content of relative percentage of each ingredient is determined by the gas chromatography area normalizing. The results show that the diphenylamine in the artificial cultivation of Anshan Jin Hu is highest.Antioxidant activity of 12 kinds of green tea are determined by flowing injection chemiluminescence, IC50 value is 0.182 - 0.840 mg/mL.