Which type of tea is fully oxidized, giving it a dark color?

Which type of tea is fully oxidized, giving it a dark color? Black tea is the answer.

Black tea is made from leaves of Camellia sinensis, the same plant used for green, white, and oolong teas. After harvesting, the leaves are withered, rolled or crushed, and exposed to controlled air, allowing their enzymes to oxidize the leaf compounds. Drying then stops the process and preserves the finished character.

Oxidation changes both color and flavor. Black tea generally becomes darker and stronger-tasting than less-oxidized teas, while green tea is heated early to limit oxidation. Oolong occupies a broad middle range, because it is only partially oxidized. “Fermentation” is sometimes used for black-tea processing, but oxidation is the more accurate term because microbes are not driving the main chemical change.

The style originated in China, where black tea is called hong cha, or “red tea,” referring to the reddish color of the brewed liquor. It also became an important long-distance trade product because it keeps its flavor longer than many green teas.