Written by Koen den Braber, Dwight Sato, and Eva Lee | 27 December 2010

Tea is the most widely consumed beverage after water. It has a cooling, slightly bitter, astringent flavor. The three most common types of tea are black, green, and oolong. There are also some less common types such as white and yellow teas and compressed teas (e.g., puerh), as well as numerous flavored and scented teas. All of these teas have in common that they use the leaves of the same plant, Camellia sinensis, but they are processed in different ways. Usually, the tip (bud) and the first two (or sometimes three) leaves are harvested for processing. Different leaf ages produce differing tea qualities, since their chemical compositions are different. Green tea is steamed (Japanese method) or roasted (Chinese method) very soon after picking to stop the oxidation (“fermentation”) process. The processed leaves still have their original green color. Oolong tea is semi-oxidized, it is left to oxidize but for a shorter time period than black tea. The color of oolong tea can vary from bright green to dark brown. Black tea is oxidized for the longest period of time, which results in a dark brown or black color.
White tea is made from new buds and young leaves plucked before they have fully opened, at which time they are still covered by fine white hairs. The highest quality white tea is made from “tea needles,” buds that have not begun to open. Lower grades contain leaves as well as buds. White tea is produced by wilting and then very gently drying the leaves, undergoing minimal oxidation. The liquor of white tea is normally clear with a light green/yellow or slightly golden color.

The term “herbal tea” usually refers to an infusion or tisane of fruit or herbs that contains no Camellia sinensis, e.g., rose hip, chamomile, peppermint, rooibos, etc.

Other products from the tea plant

Tea seeds can be pressed to produce tea oil. Oil yield is around 15%. This oil can be used for human consumption as edible oil and many industrial applications. In the cosmetic industry, for example, it is used for making hair lotions and soaps. The oil cake and other residues are used as fodder and fertilizer. However, tea seed oil has high saponin content. Saponin has some medicinal value but it is also quite toxic and limits the use of seed cake as fodder.

Green, oolong, and black teas are also used as raw material for making industrial extracts such as dyes, detergents, and sterilization and medical agents.

Tea has also traditionally been used in some parts of the world as food. In Tibet, pieces of tea are broken from tea bricks, and boiled for several hours in water, sometimes with salt. The resulting concentrated tea infusion is then mixed with butter (sometimes cream or milk) and a little salt to make butter tea. In parts of Mongolia and Central Asia, a mixture of ground tea bricks, grain flours, and boiling water is consumed. In some areas of Japan, concentrated tea is mixed with grain flour, then formed into balls and eaten. In Burma (Myanmar) tea is pickled (fermented) and eaten in a dish called lahpet.

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