Process and oxidation[edit]
Pu'er teas are often collectively classified in Western tea markets as post-fermentation, and in Eastern markets as black teas, but there is general confusion due to improper use of the terms "oxidation" and "fermentation". Typically black tea is termed "fully fermented", which is incorrect as the process used to create black tea is oxidation and does not involve microbial activity. Black teas are fully oxidized, green teas are unoxidized, and Oolong teas are partially oxidized to varying degrees.
All Pu-erh teas undergo some oxidation during sun drying and then become either:
Fully fermented with microbes during a processing phase which is largely anaerobic, i.e. without the presence of oxygen. This phase is similar to composting and results in Shu (ripened) Pu-erh
Partly fermented by microbial action, and partly oxidized during the natural aging process resulting in Sheng (raw) Pu-erh. The aging process depends on how the Sheng Pu-erh is stored, which determines the degree of fermentation and oxidization achieved.
According to the production process, four main types of pu'er are commonly available on the market:
Maocha, green pu'er leaves sold in loose form as the raw material for making pressed pu'er. Badly processed maocha will produce an inferior pu'er.
Green/raw pu'er, pressed maocha that has not undergone additional processing; high quality green pu'er is highly sought by collectors.
Ripened/cooked pu'er, pressed maocha that has undergone fermentation in the ripening process for up to a year. Badly fermented maocha will create a muddy tea with fishy and sour flavors indicative of inferior aged pu'er.
Aged raw pu'er, a tea that has undergone a slow secondary oxidation and a certain degree of microbial fermentation. Although all types of pu'er can be aged, the pressed raw pu'er is typically the most highly regarded, since aged maocha and ripened pu'er both lack a clean and assertive taste.