Partially fermented tea.

It is generally accepted that tea is the most popular beverage besides water in the world. It has its own characteristic aroma and taste. In recent years, numerous research reports have proved its effects on health maintenance. Therefore, tea is popular worldwide. Tea is made from the newly emerged tender leaves of the tea tree [Camellia sinensis (L.) O. Kuntz]. The tea tree is a perennial evergreen. Tea taxonomy is still a challenge today, not having received the attention it deserves, possibly because of the complexities involved (1). According to current taxonomy, tea trees belong to theCamellia genus of the Theaceae. It is a different species than the ornamental Camellia plants in gardens but belongs to the same genus.Within theCamellia genus, there are at least 90 or more species, andCamellia sinensis (L.) O. Kuntz is the only species that is widely made into a beverage. Camellia sinensis (L.) O. Kuntz has two big groups: the small-leaved var. sinensis and the large-leaved var. assamica that differ significantly in their growth habits, branching size, shape, texture and pose of leaf, as well as inherent yield and other characteristics. However, these two are still the main cultivated species processed into various tea beverages. Theoretically, either large-leaved var. assamica or small-leaved var. sinensis can be processed into tea with various degrees of fermentation. However, because of considerations of flavor and quality, each variety (even cultivar) has its own suitability for processing into its own kinds of tea. In general, the large-leaved species is more suitable for making fully (completely) fermented tea, and the small-leaved species is used mainly for the making of unfermented or partially fermented teas. Partially fermented tea is characteristic of China. China is probably the only country in the world that produces this kind of tea extensively. The world production of tea is about 2,900,000 metric tons per year. Black tea is the major tea, accounting for over 80% of total production; green tea is second, about 15% of the total. Because the productions of white tea, chingcha (Oolong tea), yellow tea, dark green tea, and scented tea are comparatively