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Black tea (also literally translated as red tea from various East Asian languages) is a type of tea that is more oxidized than oolong, yellow, white, and green teas. Black tea is generally stronger in flavour than other teas. All five types are made from leaves of the shrub (or small tree) Camellia sinensis, though Camellia taliensis is also ...
[10] [11] Tea has one of the highest contents of flavonoids among common food and beverage products. [7] Catechins are the largest type of flavonoids in growing tea leaves. [6] According to a report released by USDA, in a 200-ml cup of tea, the mean total content of flavonoids is 266.68 mg for green tea, and 233.12 mg for black tea. [7]
The colour of a black tea, however, is affected by many other factors as well, such as the amount of theaflavins, another oxidized form of polyphenols. Thearubigins were first studied by Roberts, E. A. H. in the 1960s [ 3 ] by the means of spectroscopy [ 4 ] or by fractionation or paper chromatography . [ 5 ]
Theaflavin (TF) and its derivatives, known collectively as theaflavins, are antioxidant polyphenols that are formed from the condensation of flavan-3-ols in tea leaves during the enzymatic oxidation (sometimes erroneously referred to as fermentation) of black tea.
It is found in high content in the dried leaves of green tea (7380 mg per 100 g), white tea (4245 mg per 100 g), and in smaller quantities, black tea (936 mg per 100 g). [2] During black tea production, the catechins are mostly converted to theaflavins and thearubigins via polyphenol oxidases .
Mainly found in the fruit skins and seeds, high levels of polyphenols may reflect only the measured extractable polyphenol (EPP) content of a fruit which may also contain non-extractable polyphenols. Black tea contains high amounts of polyphenol and makes up for 20% of its weight. [20] Concentration can be made by ultrafiltration. [21]
Theasinensin A is polyphenol flavonoid from black tea (Camellia sinensis) created during fermentation, by oxidation of epigallocatechin gallate. Its atropisomer is theasinensin D . See also
A New Class of Dimeric Flavan-3-ol Gallates, Theasinensins A and B, and Proanthocyanidin Gallates from Green Tea Leaf. (1)" . Chemical and Pharmaceutical Bulletin .