Pu-erh is a type of Chinese tea well known by its traditional history. The earliest presence of pu-erh tea can be traced back to the Shang dynasty. When it came to the Tang dynasty, pu-erh emerged to become one of the main commodities. Its popularity continued throughout the Ming and Qing dynasties.
Xishuangbanna autonomous prefecture, Simao city and Lincang city are the home to the tea trees from which the leaves are picked to process into pu-erh. The production takes place in the same regions. The finished tea product is distributed and traded in Pu’er county of Simao city, hence the name “pu-erh”.
In March 2003, the Yunnan Provincial Bureau of Standards released the definition of pu-erh tea, stating that pu-erh tea is "sourced from large-leaved camellia sinensis var. assamica from several regions within Yunnan province, produced by post-fermentation and presented in loose or compressed forms”. This is the official definition of pu-erh tea published in China thus far.
A more detailed classification of pu-erh can be defined as 3 related categories, namely sheng, lao sheng, and shou. Yunnan pu-erh is picked only from native big-leaved arbor tea plants known as camellia sinensis var. assamica. Sheng pu-erh is produced after withering, roasting, sun drying. At this point the loose-leaves are generally called maocha. The pressed sheng come in many forms, such as bing, tuo and zhuan (which means cakes, mushrooms and bricks respectively). Young sheng’s flavour has notes of bitter, astringent and vegetal, which make it more comparable to green tea.
The second category is known as lao sheng, or aged sheng. It basically is a sheng pu-erh that has been kept in storage for a period of time that ranges from years to decades. While it’s being stored, the oxidizing reaction of enzymes with polyphenols, sugar and protein from the tealeaves slowly takes place. This natural process is called post-fermentation, which transforms pu-erh’s flavours over time. As the tea’s quality and aged appeal become more prominent with time, accompanied along are the increasing rarity and appreciation of the price.
The rising popularity and price of lao sheng catalyzed the birth of the third category. In 1973, a new technology that could fast-forward the natural post-fermentation was put into production in Kunming. It was researched and developed at Kunming Tea Factory, which was a part of Yunnan branch of CNNP. By using pile-fermentation under controlled temperature and humidity, the new process engineering method known as wodui shortened the post-fermentation time that once took years or decades to within months. It renders rice-milk-like smoothness and sweetness, which characterize the flavours of lao sheng.
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