The flavour of tea is principally determined by the chemical components it contains. Volatile compounds contribute to the aroma and non-volatile compounds to the taste.
The principal components which determine the aroma, flavour and physiological action of tea are:
*An essential oil: about 0.5%, this is probably formed during fermentation.
*Caffeine: 1.8 to 5.9%. Caffeine (1, 3, 7-trimethylxanthine) is one of the major alkaloids in tea.
*Flavonoids, which were previously called tea tannins or tea polyphenols, are the main phenolic compounds comprising 20–40% of dry matter in young shoots of tea plants. The characteristics of made tea, including colour, taste, and aroma, are directly or indirectly associated with these phenolic compounds.
Some 140 components have been reported as contributing to the aroma and flavour of tea.
Chlorophyll, carotenoids, lipids and volatile compounds are not major constituents in a tea brew but they also play an important role in the development of the aroma.
The flavour of made tea is largely affected by the abundance of chemical constituents and their relative composition in young shoots.
Caffeine together with black tea polyphenols was necessary for the expression of reasonable amounts of tangy astringency. Decaffeination may change the nature of astringency from tangy to non-tangy type.
The chemical composition of tea depends on the following factors: genetic strain, climatic conditions, soil, growth altitude and horticultural practices, the plucking season, sorting (grading) of the leaves, the processing, storage, etc.
The aim of making good tea is to obtain the maximum extraction of caffeine. Most commercially available teas are blends, designed to satisfy the tastes of the customer.
Flavour and aroma of tea
