History and Production of Pu-erh
Pu-erh tea is traditionally made with leaves from old wild tea trees of Camellia sinensis assamica plants, which grow in southwest China as well as the bordering tropical regions in Burma, Vietnam, Laos, and India. Camellia sinensis assamica leaves are noticeably different from their sister plant in chemical composition therefore changing the taste and odour of the steeped tea and making it more appealing for the aging process of Pu-erh. Because of the rarity of old wild tea trees, Pu-erh is “diluted” with tea from the mountains of Yunnan. Because of this dilution process, it is now very common for tea connoisseurs to seek Pu-erh with leaves taken from only a single tea mountain's wild forests. The history of Pu-erh tea can be traced back to the Eastern Han Dynasty (206 BC–220 AD).
Pu-erh is distinctive from other teas because it usually comes in a compacted form and it ages very well. Storing Pu-erh often makes the tea take on a darker colour and gives it smoother flavour characteristics. Pu-erh leaves are packed into tea cakes or bricks which are wrapped in different types of paper materials and then stored away from excessive moisture, heat, and sunlight which helps mature the tea. The pressing and aging of Pu-erh is assumed to have originated through the natural process that occurred when stored by tea drinkers and merchants in ancient times. Compacting the tea into bricks and cakes also made it easier to transport by horseback caravans from ancient Yunnan when trading tea to Tibet and more northern parts of China.
Process and Oxidation
Pu-erh‟s are the only fermented teas, whereas other Black teas are only oxidized. Although Pu-erh teas are usually classified as post-oxidation or, just simply as Black teas, Pu-erh teas can be placed in three types of processing methods, namely: green tea, oxidized tea, and secondary-oxidation.
Pu-erhs can be green teas if they are lightly processed before being pressed into cakes. This type of Pu-erh is referred to as maocha if unpressed and as "green/raw Pu-erh" if pressed. While not always pleasant tasting, green Pu-erhs are fairly inexpensive and are known to age well for up to 30 years. Pu-erh can also be an oxidized tea if it goes through slow process oxidation for up to a year. This Pu-erh is referred to as ripened or cooked Pu-erh, and has a more mellow and pleasant flavour. Aged Pu-erhs are secondary-oxidation and post-oxidation teas. If aged from green Pu-erh, the aged tea will be mellow in taste but still clean in flavour.
These are the four main types of Pu-erh commonly available:
Maocha- Green Pu-erh leaves that are sold in loose form. The raw material for making pressed Pu-erh.
Green/raw Pu-erh- Pressed maocha that has not undergone additional processing. Quality green Pu-erh is highly sought by collectors.
Ripened/cooked Pu-erh- Pressed maocha that has undergone fermentation in the ripening process for up to a year. Badly fermented maocha will create a muddy tea with fishy and sour flavours indicative of inferior aged Pu-erhs.
Aged raw Pu-erh- A tea that has undergone a slow secondary oxidation and a certain degree of microbial fermentation. Although all types of Pu-erh can be aged, it is typically the pressed raw Pu-erh that are most highly regarded, since aged maocha and ripened Pu-erh both lack a "clean" and "assertive" taste.
Aging and Storage
Pu-erh teas of all varieties can be aged to improve flavour; the tea's physical properties will affect the speed of aging as well as its quality. These properties include:
Leaf quality- The number one factor is leaf quality. Maocha that has not been processed correctly will not age to the level of refinement as that of a properly processed maocha. The grade and cultivation of the tea also significantly influences its quality and its aging.
Compression- The more a tea is compressed the slower it will age. Therefore, looser hand and stone-pressed Pu-erhs will age more quickly than denser hydraulic-pressed Pu-erh.
Shape and size- The more surface area, the faster the tea will age. Bingcha (cake form) and Zhuānchá (tea brick) age more quickly than tuocha (bowl or nest form), or jincha (mushroom shaped Pu-erh). Larger bingcha age more slowly than smaller bingcha, and so forth.
Environmental factors of the tea's storage also affect how quickly and successfully a tea ages. They include:
Air flow- regulates the oxygen content surrounding the tea and removes odours. Moist, stagnant air will lead to dank, stale smelling aged tea. Wrapping the tea in plastic will prevent the aging process.
Odours- tea will take on the smell of strong odours, sometimes for the duration of their "lifetime." Airing out Pu-erh teas can reduce these odours.
Humidity- the more humidity the tea is exposed to, the faster the tea will age. Water accumulation on tea may increase the aging process but can also cause mould or change the flavour.
Sunlight- tea that is exposed to sunlight is apt to dry out prematurely, and will often become a bitter cup of tea.
Temperature- dry teas should not be subjected to heat due to the alteration of flavours. Exposed to low temperatures, Pu-erh‟s aging process will slow down drastically.
Preparation and Brewing
Preparing a Pu-erh brick or cake involves first breaking off compressed tea for brewing. There are many ways to do this: by flaking off pieces of the cake or steaming the entire cake until it is softened up; using Pu-erh knife (similar to an oyster knife or a rigid letter opener) to pry large flakes of tea off the cake to reduce leaf breakage.
Pu-erh is generally expected to be served Gongfu style, generally in a Yixing tea pot or in a type of Chinese teacup called a gaiwan. Optimum water temperatures are generally regarded to be around 95 degree Celsius for lower quality Pu-erhs and 85-89 degree Celsius for good ripened and aged raw Pu-erh. Steeping times last from 12-30 seconds in the first few infusions, up to 2-10 minutes in the last infusions. Generally, the higher quality aged Pu-erhs can produce multiple infusions, each with a different flavour when brewed in the traditional Gong-Fu method.
Because of the prolonged fermentation in ripened Pu-erh and slow oxidization of aged raw Pu-erh, these teas often lack the bitter, astringent properties of other tea types, and also can be more strongly and repeatedly brewed - with some claiming 20 or more infusions of tea from one pot of leaves. On the other hand, young raw Pu-erh is known and expected to be strong and aromatic, yet very bitter and somewhat astringent when brewed, since these characteristics are believed to produce better aged raw Pu-erh.
Drinking Pu-erh tea is purported to reduce blood cholesterol. It is also widely believed in Chinese cultures to counteract the unpleasant effects of heavy alcohol consumption. In traditional Chinese medicine, the tea is believed to invigorate the spleen and inhibit "dampness." In the stomach, it is believed to reduce heat and "descends qi".
Pu-erh tea is widely sold as a weight loss tea or used as a main ingredient in such commercially prepared tea mixtures. Though there is as yet no empirically backed evidence as to how Pu-erh might facilitate weight loss, the widely proposed explanations include that the tea increases the drinker's metabolism, or that the high tannin content in the tea binds macronutrients and coagulate digestive enzymes, thus reducing nutrient absorption. Although evidence is still sparse, it has been shown that rats experience reduction in body weight, blood triglycerides, and blood cholesterol following a diet containing Pu-erh tea.