Unlike most other tea styles, pu’er is fermented. Traditionally this is applied in a natural way through long storing of the tea (called sheng), alternatively, pu'er can also be artificially fermented through a controlled environment, which speeds up fermentation where the tea is stored for 45-60 days (shou). Besides the fermentation, the tea leaves also continue to oxidize, which adds a rich malty, and caramel sweetness to the tea. Sheng pu’er is often aged for years, even decades, which is not seen in many other tea types (rarely with oolong and white tea). The flavors of pu’er are often described as dark, bold, mellow, sweet, floral, rich, thick, woody and complex, although taste can vary strongly based on the pu'er category and age.
As shou pu’er is always fermented during the wet piling processing step, it is mostly categorized as a dark tea (also called post-fermented tea) in the western world. However, in China, tea producers generally tend to categorize less and view pu’er as a category on its own, independent from dark tea.
Sheng pu’er categorization is even more complex and controversial. Fresh sheng is unfermented, therefore it can’t be categorized as a dark tea. Aged sheng however, is categorized by some as a dark tea after it has undergone natural fermentation in the aging process. Though, this raises the question of how long and in which environment the tea needs to be stored to be considered a dark tea.
True pu’er is only grown in the counties and prefectures of Yunnan. Although the tea style is also produced in some other provinces of China, like Hunan and Guangdong, they are not considered true pu’er.
There are three major types of pu'er tea cultivation: cultivated tea bushes, wild arbor trees, and actual wild trees. These different methods can have a large impact on the final product.
- Cultivated tea bushes are offspring from wild tea trees and are planted in low altitudes and flatter terrain. Usually, they are considered to produce inferior-quality teas due to the use of pesticides and chemicals which are being used for fertilizer. This can also cause absence of flavors.
- Wild arbor tree cultivation is a method where trees of older plantations that have gone feral are being used. These trees are said to produce teas with better flavor because their levels of secondary metabolites are usually higher than in plantation-grown plants. Additionally, these trees tend to be cared for using organic practices (including planned pruning and soil management) which include similar methods like pollarding. Despite this good quality, "wild arbor" pu'er is not always seen as highly valued compared to truly wild-grown tea harvested from untouched forests or mountainsides.
- Lastly, pu’er teas harvested from old wild trees. These are typically the most expensive type. It is said that these types of tea leaves have more complex and deeper flavors with camphor or mint notes, transmitted by the numerous camphor trees in the region.
When it comes to pu'er processing it is important to distinguish between sheng (raw) and shou (ripe) pu'er. In general, the first steps for both categories include picking the suitable tea leaves and converting them into so-called “maocha”, which is basically the pre-state of pu'er. After that, the processes start to split up.
Optionally raw and ripened pu’er are being wilted/withered at the beginning of the process. This later helps convert the leaves into maocha, which means "light green rough tea" or just "rough tea". After plucking, the leaves are handled really carefully to prevent unwanted oxidation. If it's sunny on the day of processing, the leaves will be spread out in the sunlight to wilt and dry. If there isn't sufficient sunlight, the leaves are artificially dried by light heating, which also has an effect on the end product.
In the following, the leaves are pan-fried. This process deactivates most enzymes and nearly stops all oxidation. After the frying, they are rolled in a slightly bruised state before drying out in the sun. Because the leaves aren't fully dried, they still undergo partial oxidation in the sun, which is a unique and essential part of pu'er processing.
After the leaves are dried, the maocha is ready. This is basically the pre-stage of pu'er, which also can sometimes be bought from merchants.
Maocha is then either pressed into raw pu'er or is used for further processing to create ripe pu'er.
Ripe Pu'er or shou is pressed maocha that has been artificially fermented to imitate aged raw pu'er. Ripe pu'er is also known as cooked pu'er, which is not really accurate as the processing doesn't include cooking of the tea but the leaves are actually exposed to consistent heat through the fermentation.
This recent method of converting maocha into ripened pu’er is an invention from the Menghai Tea Factory in 1973. This processing method uses the piling of tea to prolong bacterial and fungal fermentation to imitate the aging process of raw pu'er in a warm environment. This technique is called Wò Dūi (translates to "wet piling") which in its whole includes piling, dampening, and repetitively turning the tea leaves to create a balanced fermenting environment.
Controlling the variables of humidity and microflora growth is essential to produce a high-quality end product. Poor control in these areas can result in bad ripened leaves that are decomposed, with an aroma and texture that can actually resemble compost. The fermentation process typically takes between 45-60 days.
In scientific studies with rats, the consumption of pu'er was found to significantly suppress fatty acid synthase (FAS) and also benefited reductions in cholesterol levels and triacylglycerol.
The make-up of chemicals that were responsible for these effects are catechins, caffeine, and theanine.
In traditional Chinese medicine, it is believed that drinking pu'er can revitalize the spleen. It's also said to reduce heat in the stomach area and "descends qi."
Potential Side Effects
One of the main risk factors of pu'er tea is potential leftovers or byproducts of the fermentation process. Especially very old pu'er's should be drunk with caution, as the risk of unwanted bacterial or fungal growth during the aging process exists. Usually, warning signals are a fishy smell and a wet feel to the tea. With pu'er, it is recommended to always give especially older teas one or two rinses to "wash" them and potentially remove unwanted contents.
Additionally, due to the fact that pu’er tea is fermented its caffeine content is higher compared to most other tea types. For caffeine-sensitive people, this can involve risks.
In areas where pu'er is consumed a lot, some cases of fluorosis occurred (fluoride poisoning which can cause issues with teeth and bones). This can be traced back to high levels of fluorine content in lower quality pu'er bricks with older tea leaves.
The flavors of pu'er can often be very intense, so long steeping times are not recommended unless in later infusions.
Because pu’er is derived from the tea plant Camellia sinensis, it naturally contains caffeine. For caffeine-sensitive people, this can involve risks.
After that, the first infusions are typically between 10-30 seconds and range up to 10 minutes in later ones. The water temperature can span from 85-100 degrees Celsius. Naturally individual preferences apply here.
For high-quality pu'er, up to 20 infusions with softer tasting notes can take place.