The first importation of tea into Britain was in 1660. The first tea to be exported to Britain was “Bohea” (Wuyi oolong.) The production of oolong tea was and is very costly in terms of labor and resources. This did not present a problem for China until the late 1700's.
The production of black tea in China was all about economy: they needed to produce more tea for export. This was in part due to the fact that in 1784 the Commutation Act was passed in England thereby reducing the tea tax from 119% to 12% to fight smuggling. This made tea more affordable for the masses. As a result, tea imports from China to the west (mainly Britain) went from 18.9 million pounds in 1780 to 26.7 million pounds in 1790.
Black tea production was a more simplified, more economical process requiring less fuel and less labor than oolong. Younger and older leaves were used allowing for more frequent harvests than oolong. By the 1850’s almost all provinces south of the Yangzi River became red tea producers.
The primary factor differentiating black tea from the other categories of tea is in the method of production. Different methods of processing take the tea leaves through different paths of biochemical changes resulting in different categories (i.e. white, green, yellow, black, oolong, puerh.) “Oxidation,” also referred to as "fermentation," occurs when leaf biochemical compounds, such as polyphenols, are oxidized by the leaf’s own enzymes. This starts with withering the leaves so they become soft for curling and twisting. When the leaf is curled/twisted the cell structure is broken down allowing the leaf enzymes, polyphenols & other compounds to come in contact with oxigen. For example: flavonoids and catechins in the green leaf oxidize to create theaflavins in black tea. Theaflavins--which account for 6% of black tea flavonoids—contribute to the yellow orange color of black tea infusion. Theaflavins are known to aid in reducing the incidence of cardiovascular disease, the prevention of diabetes and the reduction of blood pressure. Other flavonoids & catechins in the green leaf are oxidized in black tea production to become Theabrownins which aid in cholesterol control and Thearubigens. Over 300 compounds in fresh tea leaves can interact with one another during the bio activities in the production process to form over 500 resultant matters that constitute the aroma, taste, texture and health effects of the final product.