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In an article titled, A study on chemical estimation of Pu-erh tea quality, Yuerong Liang et al found that the chemical composition of infused Pu-erh Tea and the sensory quality of the tea are correlated.
Chemical compositions and infusion colour differences of seven pu-erh tea samples and their correlation to sensory quality were investigated. The results showed that the pu-erh tea contained 37.1 mg g-1 caffeine, 15.7 mg g-1 amino acids, 67.0 mg g-1 polyphenols and 8.41 mg g-1 total catechins, on average. Among the 17 tested volatile compounds, n-valeraldehyde was not detected. The most abundant volatile was -ionone and the next was linalool oxide II. Infusion colour analysis showed that the pu-erh tea had deep hue with E ranging from 66.8 to 79.2. Spearman’s linear correlation analysis showed that total quality score (TQS) of the pu-erh tea was significantly correlated to concentration of amino acids, linalool oxide II and infusion colour indicator E. Five components were extracted from the 34 tested indicators by principal component analysis and were regressed on the TQS to produce six Pearson’s linear regression equations for estimating sensory quality of pu-erh tea, among which two were statistically significant, ie TQS = 57.47 – 0.18geraniol + 0.33polyphenols – 1.14n-caproaldehyde – 1.38linalool oxide I + 0.21caffeine (p < 0.01) and TQS = 57.42-0.03Citral + 0.33polyphenols – 1.14n – caproaldehyde – 1.40linalool oxide I + 0.20caffeine (p < 0.01).
In an article titled, Comparative Safety Evaluation of Chinese Pu-erh Green Tea Extract and Pu-erh Black Tea Extract in Wistar Rats, Di Wang et al found that very high doses of aged Pu-erh tea extract were safe for laboratory animals.
Pu-erh teas are believed to be beneficial beverages for health since they possess several pharmacological properties such as antioxidation, hypocholesterolemia, and antiobesity properties, but their potential toxicities when administered at a high dose as concentrated extracts have not been completely investigated. In this study, the chemical components in Pu-erh green tea and Pu-erh black tea were analyzed and compared, and the safety of tea extracts was evaluated in Wistar rats. The polysaccharide, tea pigment, and flavonoid levels were substantially increased in the Pu-erh black tea, while the polyphenol and free amino acid levels were higher in unfermented green tea. Low toxicities of Pu-erh green tea extract (GTE) were observed at doses of 2500 and 5000 mg/kg/day with a 28-day subacute study. Serum biochemical data including alanine aminotransferase increased to 5000 mg/kg/day GTE males, and creatinine (Cr) increased in all 5000 mg/kg/day GTE groups and 2500 mg/kg/day GTE males. Slight bile duct hyperplasia in the liver was also observed. The target organs of GTE were considered to be the liver and kidney. Comparatively, no adverse effects were observed in Pu-erh black tea extract (BTE)-treated rats. In conclusion, a dose of 1250 mg/kg/day for GTE and 5000 mg/kg/day for BTE following oral administration could be considered safe under the conditions of this study.
A video showing how to break/flake Pu-erh tea. The complete breaking is unusual, as one will often simply break off what is needed to make a single serving of Pu-erh tea at a time.
http://www.youtube.com/watch?v=4CsEVtCgkNU
Pu-erh tea is traditionally prepared in YiXing (pronounced ee-shing) teaware. This teaware is made from Zisha clay that is mined from deep underground sources in Huanglongshan and Zhaozhuangshan. YiXing teapots are left unglazed. Without the glassy coating found on glazed pottery, the porous clay absorbs the flavor, odor, and color of the Pu-erh tea that is prepared in it. Over many brewings, these teapots are seasoned and imbue a flavor that combines the present tea and notes of previous brewings. It is common for connoisseurs to dedicate a particular teapot to a specific flavor of tea to harmonize the flavors of the tea and the teapot. The teapots are intended for single serving use and are quite small. Each teapot is a work of art and will often contain a chop mark of the artist that created the pot.
Surprisingly, the tea cup is a fairly recent inclusion in the traditional preparation of Pu-erh tea. Prior to 1350AD, most Chinese teas would be consumed directly from the teapot. In the Ming dynasty the gaiwan was added to the traditional teaset and is now one of the main ways that teas, including Pu-erh tea are prepared and enjoyed in China. Each gaiwan is a matched set comprised of a saucer, bowl and lid. Unlike the the YiXing teapot, the gaiwan is glazed to prevent the teaware from becoming seasoned or discolored over time. The base material for a gaiwan is most often porcelain. Because porcelain quickly distributes heat, porcelain gaiwans are excellent for aged and fine pu-erh preparation at lower temperatures. The gaiwan teaset permits tea to be infused directly in the bowl and then be enjoyed from the bowl or served into tasting cups. While gaiwans are not as good as yixing pots for most pu-erh teas, the glazed gaiwan can be used conveniently for the preparation of many types of tea.
The pressing of Pu-erh tea into cakes and the aging of the tea perhaps originated in the need to transport the tea conveniently from Yunnan to Tibet and northern China and in the natural aging process that happened in tea storerooms and during transport.
While Pu-erh is predominantly pressed into cakes, an interesting variety of additional compact shaped may be used including squares, bricks, bowls, mushrooms, and melons. Most Pu-erh tea is distributed in small cakes weighing about 357 grams. Regardless of the final shape, each of these forms is created by steam-moistening the máochá or ripened tea leaves to improve cohesion prior to compressing the tea into the desired form. Occasionally, cakes are made of older leaves mixed with the current year leaves. This mixing is, unfortunately, difficult to get information about as it is considered a trade secret.
Next, the desired amount of tea is placed within a cloth and under the press. This compression can be preformed mechanically or by hand with a hydraulic or lever press. Traditionally, a large rock was used for the pressing. A small piece of paper called a Nèi fēi will also be pressed in with the tea, as a sign of authenticity that resists easy tampering. The pressed tea must be allowed to dry prior to packaging and sale.
When sold individually, each pressed cake will come in a cotton wrapper printed with information on the production location and year of production. These wrappers also sometimes include interesting artwork. As mentioned above, the cake will have an impressed authenticity paper embedded in the tea with manufacturer information. Some cakes will also include a loose flyer with additional information about the tea. Pu-erh is also sold wholesale in larger bamboo containers called tong.
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IQ by Innovations Young Pu-erh Tea:  Puerh is an aged tea from China that is fermented and matured to develop a unique mellow, slightly wet earthy character. The finest puerhs are aged for up to 50 years and become more mellow and soft over time. In China, this category of tea is considered to be a medicinal beverage that helps metabolize fats. It is ideal for digestion and is said to help prevent hangovers.
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