Oolong tea is semi oxidised, though the degree of oxidation varies from maker to maker.
Oolongs have extra steps (compared with black and green teas) in the withering stage that help develop its characteristic aroma.
The freshly plucked green leaves are first spread out in the sun for a couple of hours before being transferred to the withering trough inside the factory. During the moisture loss stage, the leaf is tossed by hand many times, which causes slight bruising and the production of aroma volatiles (these are the parts of the tea’s taste that you sense through your nose rather than in your mouth) this tossing and the rolling which is need for the ball oolongs is extremely hard work.
Oolong tea is also often given a final firing at higher temperatures to further develop a typical oolong flavour.
The leaves can be loose like Formosa Oolong, Phoenix Dancong, Da Hong Pao and our China Oolong or rolled into small balls or pellet shapes like Dong Ding, Sumatra Chin Chin, Ti Guan Yin and Dark Pearl.