Pu-erh tea

„The process used to convert máochá into ripened pu'er is a recent invention that manipulates conditions to approximate the result of the aging process by prolonged bacterial and fungal fermentation in a warm humid environment under controlled conditions, a technique called Wò Dūi (渥堆, "wet piling" in English), which involves piling, dampening, and turning the tea leaves in a manner much akin to composting.“

„Sourness in Raw Puer is due mostly to inadequate airing after the rolling process or, after pressing tea into cakes, they have been immediately exposed to the sun. The tea soup will likely be turbid.“