Investigation and comparison of the chemical constituents in green and black tea (Camellia sinensis) using physicochemical analysis methods

Abstract

Introduction. Green and black teas are one of the most consumed beverages in the world, both containing a wide range of active substances and proved to have beneficial effect to tea consumers’ health. Green and black tea are produced from the same plant Camellia sinensis (L.), but the further preparation of the tea leaves differ. [1,2] In this study the main objective was to analyze quantitative and qualitative parameters of aqueous black and green tea extracts, and to determine the conditions (by changing the water temperature and the extraction time) under which the amount of chemical constituents is the highest. The chosen active substances were caffeine, theobromine and theophylline. Materials and Methods. Black and green tea samples were purchased from the same manufacturer in a community shop in the form of loose tea leaves. Both teas‘ origin country is Sri Lanka, Ceylon region. The samples were grinded separately and weighed into sample sizes of 2,0 g each. Each sample was mixed with 50,0 ml distilled water of the chosen temperature. Chosen temperatures were 70oC and 100oC and the extraction times were 3 min, 5 min, 10 min, 15 min. One sample of each tea was made using room temperatured distilled water and left in room temperature for 22 h. After the extraction of the determined period of time samples were filtered through a paper filter and chilled samples were used for further HPLC analysis. Analysis was conducted using a Waters 2695 chromatographer, 2998 PDA detector, ACE C18 (250mm × 4,6mm) column, sorbent particle size of 5 μm, gradient pump mode, mobile phase consisting of trifluoroacetic acid (TFA) and acetonitrile (ACN). The amounts of caffeine, theophylline and theobromine were determined by comparing sample results with standard solutions of the chosen substances. Results and discussion. Caffeine, theobromine and theophylline determination was conducted by HPLC. In green tea extracts the highest amount of caffeine (2,696 mkg/ml) and th