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Caffeine is stored in tea leaves in two places. Firstly, in the cell vacuoles where it is complexed with polyphenols. This caffeine probably is released into the mouth parts of insects, to discourage herbivory. Secondly, around the vascular bundles, where it probably inhibits pathogenic fungi from entering and colonizing the vascular bundles. [224]
Tea contains small amounts of theobromine and theophylline, which are xanthines and stimulants, similar to caffeine. [59] Fresh tea leaves in various stages of growth. The astringency in tea can be attributed to the presence of polyphenols. These are the most abundant compounds in tea leaves, making up 30–40% of their composition. [60]
Black tea also comes from the Camellia sinensis plant, but unlike green tea, the leaves are fully oxidized, giving them their hallmark black color. Black tea has more caffeine than green tea but ...
Camellia sinensis is a species of evergreen shrub or small tree in the flowering plant family Theaceae.Its leaves, leaf buds, and stems can be used to produce tea.Common names include tea plant, tea shrub, and tea tree (unrelated to Melaleuca alternifolia, the source of tea tree oil, or the genus Leptospermum commonly called tea tree).
All tea leaves contain fluoride; however, mature leaves contain as much as 10 to 20 times the fluoride levels of young leaves from the same plant. [9] [10]The fluoride content of a tea leaf depends on the leaf picking method used and the fluoride content of the soil from which it has been grown; tea plants absorb this element at a greater rate than other plants.
The leaves of the coca plant contain alkaloids that—when extracted chemically—are the source for cocaine base. The amount of coca alkaloid in the raw leaves is small, however. A cup of coca tea prepared from one gram of coca leaves (the typical contents of a tea bag) contains approximately 4.2 mg of organic coca alkaloid. [1]