Overview:Pu-erh or Pu'er tea is a variety of fermented dark tea produced in Yunnan province, China. It is known for their rich earthy flavor, medicinal qualities, moderate in taste, not as strong as black tea. It can be safe for weight loss uses, digestion, warm stomach ... without side effects.
Pu-erh or Pu'er tea is a variety of fermented dark tea produced in Yunnan province, China. Fermentation is a tea production style in which the tea leaves undergo microbial fermentation and oxidation after they are dried and rolled. This process is a Chinese specialty and produces tea known as Hei Cha (黑茶), commonly translated as dark, or black tea (this type of tea is completely different from what in West is known as "black tea", which in China is called "red tea" 红茶). The best known variety of this category of tea is Pu-erh from Yunnan Province, named after the trading post for dark tea during imperial China.
Pu'er traditionally begins as a raw product known as "rough" Mao Cha (毛茶) and can be sold in this form or pressed into a number of shapes and sold as "raw" Sheng Cha (生茶). Both of these forms then undergo the complex process of gradual fermentation and maturation with time. The Wo Dui process (渥堆) developed in the mid-1970s by the Menghai and Kunming Tea Factories  created a new type of pu-erh tea, whose legitimacy is disputed by some traditionalists. This process involves an accelerated fermentation into "ripe" Shou Cha (熟茶) which is then stored loose or pressed into various shapes. All types of pu-erh can be stored to mature before consumption, which is why it is commonly labelled with year and region of production.
Darkening tea leaves to trade with ethnic groups at the borders has a long history in China. These crude teas were of various origins and were meant to be low cost. Darkened tea or Hei Cha, is still the major beverage for the ethnic groups in the southwestern borders and, until the early 1990s, was the third major tea category produced by China mainly for this market segment.
There had been no standardized processing for the darkening of Hei Cha until the postwar years in the 1950s where there was a sudden surge in demand in Hong Kong, perhaps because of the concentration of refugees from the mainland. In the 1970s the improved process was taken back to Yunnan for further development, which has resulted in the various production styles variously referred to as Wo Dui today. This new process produced a finished product in a manner of months that many thought tasted similar to teas aged naturally for 10–15 years and so this period saw a demand-driven boom in the production of Hei Cha by the artificial ripening method.
In recent decades, demand has come full circle and it has become more common again for Hei Cha, including Pu-erh, to be sold as the raw product without the artificial accelerated fermentation process.
Pu-erh tea processing, although straightforward, is complicated by the fact that the tea itself falls into two distinct categories: the "raw" Sheng Cha and the "ripe" Shou Cha. All types of pu-erh tea are created from máochá (毛茶), a mostly unoxidized green tea processed from a "large leaf" variety of Camellia sinensis (C. sinensis assamica) found in the mountains of southern Yunnan.
Maocha can be sold directly to market as loose leaf tea, compressed to produce "raw" Sheng Cha, naturally aged and matured for several years before being compressed to also produce "raw" Sheng Cha or undergo Wo Dui ripening for several months prior to being compressed to produce "ripe" Shou Cha. While unaged and unprocessed, Maocha pu-erh is similar to green tea. Two subtle differences worth noting are that pu-erh is not produced from the small-leaf Chinese varietal but the broad-leaf varietal mostly found in the southern Chinese provinces and India. The second, is that pu-erh leaves are picked as one bud and 3-4 leaves whilst green tea is picked as one bud and 1-2 leaves. This means that older leaves contribute to the qualities of pu-erh tea.
Ripened or aged raw pu-erh has occasionally been mistakenly categorized as a subcategory of black tea due to the dark red color of its leaves and liquor. However, pu-erh in both its ripened and aged forms has undergone secondary oxidization and fermentation caused both by organisms growing in the tea and free-radical oxidation, thus making it a unique type of tea. This divergence in production style not only makes the flavor and texture of pu-erh tea different but also results in a rather different chemical makeup of the resulting brewed liquor.
The fermented dark tea, Hei Cha (黑茶), is one of the six classes of tea in China, and pu-erh is classified as a dark tea (defined as fermented), something which is resented by some who argue for a separate category for pu-erh tea. As of 2008, only the large-leaf variety from Yunnan can be called a pu-erh.