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.“

„cha qi; 茶气 - Tea nature. The inherent energetic qualities in tea. That which makes it tea. Sometimes rather unsatisfactorily interpreted as 'tea energy'; translating qi as energy suggests perhaps a rather too narrow idea of qi but it is an interesting term to consider since many people use the term. Ideas and experiences of cha qi vary considerably; the taste of tea, the appearance of the leaves (particularly after steeping i.e. the life in the tea), any physical or psychological experiences one may have as a result of drinking tea are all aspects of cha qi. One cannot satisfactorily dissociate one from the other just as one cannot isolate sunshine from wind, which are both manifestations of weather, tian qi. If it did not have cha qi it wouldn't be tea, it would be something else. From a western point of view perhaps, cha qi is due, in some good part, to the presence of caffeine, theine, etc. The active constituents.“