Tea Processing

The flavor of tea is partially determined by how the tea leaf is processed. Processing tea may include withering, rolling, fermenting, and drying. The four main types of tea are white, black, green, and oolong The withering stage is begun after the plucking of the leaf. Plucking of the finest teas is done by hand since machine picking can damage the leaves. Typically only the top two leaves and bud are used. After plucking, the fresh leaves are spread into layers on trays called tats. These may simply be sections of coarse fabric. The leaves are then left to wither, occasionally in the direct sun (Sowme White Tea is a good example). Open air withering has often been replaced by a variety of mechanized systems. These mechanized systems greatly reduce withering time and may or may not lower the quality of the final product. After withering, the leaves are rolled. At this stage, the leaf is distorted and bruised to break open their leaf cells. The traditional method of rolling was done by rolling many leaves by hand. Today leaves may be machine-rolled. Some machines burst the leaf cells so thoroughly that the withering stage is no longer necessary. These machines, however, do not produce the larger leafy grades of teas. Next, the leaves are again spread out and left in a warm place to ferment, The fermentation stage begins when the leaf cells are broken while rolling. This is causes a series of chemical reactions where the enzymes affect the tannin and natural oils in the leaves. During fermentation, the leaf color deepens and flavor develops. This can last many hours. Fermentation is stopped by heating (or firing). This preserves the leaves and halts the oxidation. Traditional firing was done on large pans or screens over fire. Today a drier is often used that blows heated air into a chamber. Black tea is the most popular type in the United States, but is not consumed much in other parts of the world. Black teas are processed the longest and have a rich, reddish brown color and full aroma and flavor. Some well known types of black tea are Assam, Ceylon, Darjeeling, and English Breakfast. Green tea is basically an unfermented tea. The leaves are steamed immediately after harvest to prevent fermentation and maintain pliability. The leaves are then rolled and fired until they turn dark green. They are then dried and either crushed into small pieces or ground to a powder. Green teas have a pale color and less aroma and flavor than black teas. Sencha, Dragonwell and Gunpowder are very popular green teas. White tea starts with just the tightly rolled buds of the camellia sinensis plant. White tea does not go through any oxidation. In order to prevent oxidation white teas are baked at temperatures under 40 degrees C. (and never fired), after letting them wither (air dry) for a period of time. They are often withered naturally in the sun. There is no rolling, breaking, or bruising of any kind. Silver Needles White Tea is one of the rarest most exquisite of all white teas. Oolong tea is semi-fermented. The leaves are briefly withered; then lightly rolled by hand until they become red and fragrant. They are then fermented for about onefourth the time of black tea and steamed to stop the process. They yield a tea that is in between the flavors, colors, and aromas of green and black teas. The best known oolong tea is Formosa Oolong from Taiwan.