In the first stage of making tea – called withering – moisture is removed from freshly-picked tea leaves by rolling them over a current of hot air in the machine shown below.
The next stop is to the rotovane, where the machine shreds the withered tea leaves. This breaks them open and allows them to oxidize, which is the only thing that distinguishes green tea from black tea.
Finally at the oxidization bed, enzymes in the withered and shredded tea leaves are exposed to air. This darkens the leaf, providing its color, flavor, and aroma. When the desired oxidation level is achieved, the process is stopped by heating and drying.