Wo Dui (Pile Fermentation)
Wo dui is the controlled pile fermentation used to make shou pu'er: moistened maocha is stacked in heaps for weeks so microbes and heat rapidly darken and mellow it.
Definition
Wo dui (渥堆, "wet piling") is the step that turns raw pu'er leaf into shou, or ripe, pu'er. Sun-dried maocha, the base leaf of pu'er, is sprayed with water and heaped in piles often a meter deep in a warm room, sometimes covered with cloth. Bacteria, yeasts and molds, including Aspergillus species, multiply in the damp pile. Their activity and the heat it generates break down and transform the leaf's compounds. Workers turn the pile every several days to control temperature and moisture. Modern wo dui for pu'er was developed in 1973 at the Kunming Tea Factory and adopted at Menghai and other Yunnan factories soon after. The aim was to reproduce, in weeks, some of the dark, smooth character that sheng pu'er develops over many years of storage. A typical ripe pu'er pile runs about 40 to 60 days, and makers sell light, medium and heavy fermentations. Pile fermentation has older relatives in other dark teas: Hunan Anhua dark tea, Guangxi Liu Bao and Sichuan brick tea all involve piling of damp leaf. After wo dui the leaf is dried, sorted and either sold loose or steamed and pressed into cakes, bricks or tuocha.
In Depth
Pile taste: new shou pu'er often smells of damp earth, fish, or compost, a note called dui wei (pile flavor). It fades with a year or more of airing and storage. A strong, sour or musty pile smell in a tea several years old suggests poor fermentation or storage.
Brewing: 95-100°C (203-212°F), 5-7 g per 100 ml in a gaiwan or clay pot. Rinse once or twice for 5-10 seconds, then steep 10-20 seconds and lengthen gradually. Shou is forgiving and rarely turns bitter.
Fermentation level: light-fermented shou keeps some green, astringent character. Heavy-fermented shou is very dark, thick and smooth, with less complexity. Medium is the most common commercial target. Factory recipe numbers on wrappers, such as Menghai 7572, identify a particular blend and fermentation.
See Also
- Ripe Pu'er
- Dark Tea (Hei Cha)
- Menghai Tea Factory