The diagram delineates the linear process of commercial tea production, from the cultivation of the plant to the final product, with the degree of oxidation determining the variety.
Overall, the process commences with the growth and harvesting of tea leaves and culminates in one of five distinct tea types. The most pivotal stage is the processing of the plucked leaves, where the application and duration of oxidation govern the ultimate classification.
In the initial stage, tea plants are cultivated until mature, at which point the leaves are hand-plucked. The freshly harvested leaves are then withered; this involves air-drying them to reduce moisture content, thereby rendering them pliable for subsequent stages.
The subsequent steps diverge based on the desired tea type. For green tea, the leaves are steamed immediately to halt oxidation, then rolled and dried. For the other varieties, the withered leaves are either rolled or crushed to rupture the cell walls, initiating oxidation. This leads to the crucial stage of controlled oxidation (commonly, though inaccurately, termed ‘fermentation’). Here, the duration is precisely managed: oolong tea undergoes partial oxidation, whereas black teas are fully oxidized.
Finally, all leaves are oven-dried to terminate the oxidation process and ensure preservation. The finished product is then sorted into one of five categories: white tea, which is barely oxidized; green tea, which is unoxidized; oolong tea, partially oxidized; and black tea, which is fully oxidized and distinguished by leaf size.