PROCESSING

Tea is generally divided into categories based on how it is processed At least six different types are produced:
White: wilted and unoxidized;
Yellow: unwilted and unoxidized but allowed to yellow;
Green: unwilted and unoxidized;
Oolong: wilted, bruised, and partially oxidized;
Black: wilted, sometimes crushed, and fully oxidized; called (called "red tea" in Chinese tea culture);
Post-fermented: green tea that has been allowed to ferment/compost (called "black tea" in Chinese tea culture).
The most common are white, green, oolong, and black.

After picking, the leaves of C. sinensis soon begin to wilt and oxidize unless immediately dried. An enzymatic oxidation process triggered by the plant's intracellular enzymes causes the leaves to turn progressively darker as their chlorophyll breaks down and tannins are released. This darkening is stopped at a predetermined stage by heating, which deactivates the enzymes responsible. In the production of black teas, halting by heating is carried out simultaneously with drying. Without careful moisture and temperature control during manufacture and packaging, growth of undesired molds and bacteria may make tea unfit for consumption.

Although single-estate teas are available, almost all tea in bags and most loose tea sold in the West is blended. Such teas may combine others from the same cultivation area or several different ones. The aim is to obtain consistency, better taste, higher price, or some combination of the three.

Tea easily retains odors, which can cause problems in processing, transportation, and storage. This same sensitivity also allows for special processing (such as tea infused with smoke during drying) and a wide range of scented and flavoured variants, such as bergamot (found in Earl Grey), vanilla, and spearmint.