Pooh

from Wikipedia, the free encyclopedia
Different forms of pressed pu-erh
Brick tea

Pu-Erh ( Chinese  普洱茶 , Pinyin pǔ'ěr chá ) is a type of tea , in the southern Chinese province of Yunnan from leaves of Assam variant of the tea plant ( Camellia sinensis var. Assamica is established (L.) O. Kuntze), in the border region of southern China, Burma and India is indigenous and today in various cultivars are grown. The tea leaves intended for the production of Pu-Erh are pressed into molds and dried after the first processing steps. The pressed tea can be stored for years to decades and continue to mature in the process.

The infusion results in a dark red-brown tea with an earthy, spicy taste. Pu-erh one in China to the category of 黑茶 , hēi chá  - "darker (literally, black) tea". Its production method distinguishes pu-erh from black tea , which is known in China as 红茶 , hóng chá  - "red tea". In this type of tea, the enzymes contained in the leaves react with oxygen in the air, which oxidize the leaves.

Pressed tea is known in various tea-growing regions of the world, but only the tea produced in the region around the former tea trading town of Pu'er in Yunnan has been allowed to bear the protected trade name Pu-Erh since 2008.

Tea cultivation in Yunnan

history

Ethnic Diversity in Yunnan Province: Lincang City (8), Pu'er City (7), Xishuangbanna Autonomous District (16)

In Yunnan, Pu-Erh is mainly grown in three regions on the upper reaches of the Mekong River : in the Dai Autonomous District of Xishuangbanna and in the administrative urban area of Pu'er and Lincang .

Since the 10th century at the latest, tea pressed into tea bricks or patties has been used as a commodity because of its better shelf life and transportability, which was transported over long distances on the tea routes and exchanged for goods and horses in the northern and western border regions of China.

Despite its economic importance for the Chinese Empire until the 14th century, tea cultivation and processing were in the hands of the indigenous Yunnan ethnic groups, the Blang , Wa , De'ang , Hani , Akha , Lahu and Jino . In the 13th century, the Yuan emperors conquered the region; a targeted population policy led to the immigration of Han Chinese from north and south-east China. Han Chinese tea merchants did not settle there until the early 18th century. They dominated the tea trade in the late 19th and early 20th centuries. Although the immigrants exerted a profound influence on the culture and economy, the distinctive ethnic and cultural diversity remained in parts and has also shaped modern China since the beginning of the reform and opening-up policy in the 1980s.

biodiversity

The broad-leaved Assam variant of the tea plant is originally native to the Yunnan Province and its neighboring regions in southwest China (Sichuan, Guangxi and Guizhou) as well as in Laos, Vietnam, Myanmar, Cambodia and northeast India. These regions have a particularly high level of biodiversity. The different habitats and local varieties of the tea plant from which Pu-Erh is obtained lead to a great genetic, plant-chemical and taste diversity of the tea produced there. Today, 4 categories, 31 species and 2 varieties of the tea plant are known in Yunnan, of which 25 species and 2 varieties occur only in Yunnan. Species that grow in the wild, such as Camellia taliensis, C. grandibractiata, C. kwangsiensis, C. gymnogyna, C. crassicolumna, C. tachangensis, C. ptilophylla and C. irrawadiensis, can form new varieties through accidental introgression or as part of breeding .

Cultivation forms

The targeted tea production in special cultivation systems goes back around 1000 years in this region. As GIAHS pilot site is from the "Traditional Pu'er tea Agrosystem" FAO recognized.

In Yunnan, tea is either obtained from wild tea plants, in agricultural forests or mixed cultures , or grown in monoculture in tea plantations. The culture in forests or in mixed cultivation goes back to the centuries-old tradition of the Blang, Akha and Lahu ethnic groups of Yunnan. Tea plants in agricultural forests grow as trees two to eight meters high in forest areas of approx. 0.5 to 3 hectares that have been cleared through targeted clearing. The tea trees are shaded by larger trees, with ground cover plants growing under them. The ecosystem of the agricultural forests is still similar to that of the original forest, so that agrochemical products can be dispensed with. Tea cultivation in terraces did not emerge in Yunnan until the 1970s.

Growing areas

Pu-erh is made in many prefectures and autonomous counties in Yunnan Province, including Lincang, Dehong, Simao, Xishuangbanna, and Wenshan . Of historical significance is the growing area of the Six Great tea mountains ( 六大茶山 , liù dà chá shān ) in Xishuangbanna on the east bank of the Mekong:

  1. Gedeng Shan ( 革登山 , Gedeng shān )
  2. Yiwu Shan ( 易武山 , yìwǔ shān )
  3. Mangzhi Shan ( 莽枝山 , mǎngzhī shān )
  4. Manzhuan Shan ( 蠻磚山 , mánzhuān shān )
  5. Yibang Shan ( 倚邦山 , yǐbāng shān )
  6. Youle Shan ( 攸樂山 , Youle shān )

Until the immigration of the Han Chinese in the second half of the 17th century, tea was cultivated in this region by the indigenous peoples under the rule of the Dai aristocracy in Jinghong ; with immigration, the area under cultivation expanded. The loose tea was roughly processed by the producers in advance and sold to Han merchants, who processed, pressed and sold the tea in commercial factories (including Song Ping Hao and Tong Qing Hao , whose products are now collectibles). The Yiwu Shan tea trade prospered at the end of the 18th century. Trade relations existed with Beijing, Southeast Asia, Hong Kong and Tibet. During the Qing Dynasty , the indigenous rulers were gradually replaced by Chinese government officials. In 1729 the prefecture of Pu'er was established. From 1732 to 1904, tea from the Six Mountains was sent to the imperial court as tribute tea ( 貢茶 , gong chá ). The tea trade continued during the Republic of China (1912–1949) and only came to a standstill during World War II and the civil war until 1949. Until the 1990s, the cultivation area only produced raw material for the state tea factories. In the late 1990s, Taiwanese tea collectors became interested in old, ripened teas from the region and production was resumed.

processing

Pressing Pu-Erh

Today, pu-erh is made using two processes that continue to exist side by side. Common to both methods is the starting product obtained by withering, steaming and rolling of green tea crude tea produced ( 毛茶 , máo Cha  - "green crude tea"). This can be sold dried and in the form of loose leaves.

Raw (Sheng) Pu-Erh

According to the traditional method, Máo Chá is pressed into molds. Freshly squeezed tea 生茶 , shēng chá  - "Raw Tea" matures into 老生茶 , lǎo shēng chá  - "old / mature raw tea" on. This process can last for years to decades.

The traditional method, which has been known since the Song era (960–1279) at the latest and was common until the 1960s, originally served to preserve green tea for transport and long-distance trade. For this purpose, the tea leaves are withered in the sun, steamed and pressed under controlled heat into flat, brick or ball shapes. During transport or storage, the tea continues to mature through reactions taking place between the natural components of the tea leaves. The maturation period was at least five years; the tea becomes more flavorful with age. Microorganisms do not play a decisive role in this process.

Mature (Shu) Pu-Erh

In 1972, the state-run tea factory in Kunming developed an accelerated process ( 渥 堆 , wò duī  - "wet heap") suitable for mass production , in which the raw tea goes through a controlled fermentation before it is pressed. The tea produced in this way is called 熟茶 , shúchá  - "ripe tea" or post-fermented tea. The tea is ready to trade after a few weeks, but like Sheng Pu-Erh it can continue to mature.

The raw tea is moistened with water, loosely spread out in long, narrow piles in a closed room and covered with a straw mat or tarpaulin. The tea matures under controlled conditions in a fermentation process similar to composting, mediated by microorganisms such as the molds Penicillium , Aspergillus and yeast . The composition of the microorganisms is subject to changes during the fermentation process, which depend on the degree of ripeness of the leaves and the prevailing temperature and humidity. The procedure only takes about 48 days. Then the tea is pressed.

Fermentation process

The fermentation of Pu-Erh takes place largely in the dry state; Moisture or water does not play a special role. Essentially, polyphenols react with the enzymes in the leaves (endo-oxidation) and with microorganisms (exo-oxidation). In addition, the microorganisms metabolize carbohydrates and amino acids from the leaves. The composition of the microorganisms involved in the fermentation process differs from region to region and even between individual factories, but Aspergillus (A.) niger is the most commonly detected. Other Aspergillus species involved in the fermentation process are A. luchuensis and A. acidus .

Press

Traditionally, the loose tea leaves are pressed into their shape by first steaming them in a metal cylinder for about 10 seconds and then shaping them into a ball by hand in a cloth bag. Then the tea is pressed into the desired shape under a stone weight on which a person stands. While this process is still used in the area of ​​the Six Great Mountains, Pu-Erh from Menghai is mostly pressed by machine today.

classification

Pu-Erh is classified according to the cultivation method, mold, type of production, growing region and production time.

Cultivation method

Pu-erh can be grown in a number of ways, with tea from wild tea trees having the best reputation:

  • Plantation bushes ( 灌木 , guànmù ; 台地 , Taidi ): tea bushes from seeds or cuttings of wild tea trees grown in lower altitudes and flatter terrain, usually using artificial fertilizers and pesticides.
  • Feral bushes ( 野放 , Yefang ): The bushes grow in human scale, but overgrown plantations.
  • Wild Trees ( 古树 , Gushu  - "Old Tree"): Tea from old, wild bushes, even from the wild species Camellia taliensis

Compression molds

image designation description
Haiwan bingcha.jpg 饼茶 , Bǐngchá 'cake' or 'slice tea ' Round, flat disc, weight between 100 g to over 5 kg, the most common shapes weigh 357, 400 and 500 g. Depending on the mold, the edge of the disc can be rounded or straight. Traditionally, seven bings are packed into one container. The picture shows the label called Nèi fēi 'Inner Trade Mark' in the tea cake .
Xiaguan 1992 tuo cha.jpg 沱茶 , Tuocha , Knauftee ' Convex, knob-like shape. Weight 3 g to 3 kg or heavier, the most common are cakes of 100, 250 and 500 g. The name tuocha is derived from the pressed form, but could also be in connection with the old tea route across the Tuo River. In earlier times, the tuocha cakes had a hole in the middle so that they could be threaded onto a rope for transport.
Zhuan cha.jpg 砖茶 , Zhuānchá , brick ' Thick, rectangular tea block or tea brick, weighing between 100 g and 1 kg; Zhuancha bricks were transported on the historic tea routes .
Catch cha.jpg 方茶 , Fāngchá  - "square tea " Flat tea cuboid, 100–200 g in weight.
Jincha.jpg 紧茶 , Jǐnchá  - "mushroom tea" 'mushroom' Literally “dense tea”, shaped like a túochá of 250–300 g, but with a “stem” instead of a convex back, so that the pressed shape looks like a mushroom.
Puerh Dragon Pearl Tea.jpg 龍珠  /  龙珠 , Longzhu  - "dragon pearl" Small balls or rolls, suitable for a single portion of 5–10 g.
Golden melon.jpg 金瓜 , Jīnguā  - "melon or gold melon" The shape is similar to the tuóchá , but is larger, the thicker body is decorated with stripes like a melon. This form was chosen for the imperial " tribute tea " ( 貢茶 ).

Year of manufacture and labeling

Labeling of a tea shop ( bing ): Nèi fēi (trade mark), Nèi piào (packaging label ), paper sleeve.
Bing with the trademark of China Tea Corporation, Yunnan Branch.

Since properly stored Pu-Erh ripens, press cakes that are sometimes decades old still exist, which at auctions fetch similarly high prices as old wines from well-known wineries.

Prior to the founding of the People's Republic of China in 1949, pu-erh was manufactured in small quantities by private companies, including the now legendary family-run businesses Song Ping Hao and Tong Qing Hao. The manufacturers did not specialize in tea, but traded in addition to tea in other agricultural products such as rice. Due to the relatively high price, demand was low at that time. The few press cakes still available today fetch prices of several hundred thousand dollars at auctions for rare teas. Pieces from this period were not wrapped in paper, as they are today, but only had a label visibly embedded in the tea ( 内飞  /  內飛 , Nèi fēi  - “internal trade mark”); Containers were also provided with a 内票 , Nèi piào  - “packaging label”. In addition to the tea itself, only the labels enable the tea cakes to be assigned or different brands from the same company to be distinguished, such as "Red label" or "Blue label" Song Ping Hao.

After 1949 all of the companies were nationalized. Some of the state-owned factories, founded in the 1950s as the 勐海茶厂 , menghai Chachang  - "tea factory of Menghai " in Autonomous Prefecture of Xishuangbanna produce in Yunnan (. Est 1940) today. In 1973 this company was one of the first to introduce the fermentation process to produce ripe pu-erh. China Tea Corporation, Yunnan Branch was established in 1950 to better control production and quality . Until the company was privatized in 1996, the paper packaging for the tea cakes was branded with the large printed characters for tea (茶), surrounded by a ring of eight 中 (zhōng 'middle').

In 1972, the CNNP (China National Native Produce & Animal Byproducts Import & Export) was founded, which controlled the entire production of Pu-Erh. The three largest factories at that time were in Menghai, Xiaguan (in the Dali Autonomous District ) and Kunming . Pu-Erh was marketed under the trade name 七子饼茶 , qī zǐ bǐng chá  - "Seven Sons Cake Tea". Tea cakes from this period have a Nèi-piào label with a description. For the first time, the packaging has romanized pinyin lettering for export. With the privatization of the tea factories from the 1990s onwards, manufacturers sold their products under their own brands. Today, security labels are stuck on to protect against counterfeiting.

preparation

In Chinese tea culture , both pu-erh and oolong tea are brewed according to the gongfu method , which was invented in Yunnan. The tea is brewed repeatedly with boiling hot water for only a short time. The first infusion is poured off after a few seconds (the tea is "washed") and not drunk.

Scientific investigations

Laboratory studies

Animal studies on rats that were given Pu-erh tea extracts with the feed showed reduced levels of LDL cholesterol and, in conjunction with in vitro experiments , uncovered possible specific mechanisms by which natural components of the tea leaves inhibit the synthesis of cholesterol in liver cells can. Pu-erh showed in cell culture also anti-mutagenic and anti-microbial properties and was able to inhibit the growth of tumor cells.

Observations on people

The enjoyment of Pu-Erh is - comparable to the Japanese tea ceremony - an identity-forming social practice that emphasizes the experience of taste, well-being and attention. A study in Yunnan examined the perception of 100 people who drank green and ripe pu-erh from different forms of cultivation (small-scale plantations and tea plantations) and different processing. The tea was made according to the gong fu method; Color and taste profiles of the successive infusions of the individual tea samples were created using HPLC and the DPPH radical scavenger test. The total content of catechins , methylxanthines and the capacity to scavenge free radicals were measured . It turned out that the growing conditions and processing techniques as well as the successive infusions had a significant effect on the chemical profile - the ability to catch free radicals - as well as on the taste. The infusions described as bitter or bittersweet had the highest catechin concentration and the highest ability to absorb free radicals.

Randomized controlled studies on the health effects of long-term use of Pu-Erh cannot currently be found in medical databases. The German Nutrition Society contradicts the claim that Pu-Erh is suitable as an appetite suppressant and warns against excessive consumption because of the caffeine and theobromine content.

Very high levels of fluoride have been found in some pu-erh teas because they are generally made from older leaves and stems that are particularly susceptible to fluoride. In areas like Tibet, where pressed tea is widely drunk, the consumption of the tea has led to fluorosis .

Role of microorganisms

The technique of fermenting organic material with the help of suitable microorganisms serves to preserve food; among other things, there is a displacement of pathogenic organisms and those that would spoil food. A large number of microorganisms, especially molds of the species Aspergillus and Penicillium , can be detected in recently processed tea leaves. They also appear later as contamination in improperly (too warm, too humid) stored tea.

Aspergillus species have been found in natural products such as coffee beans, grain products, milk powder, chocolate, soy sauce and tofu; it has been linked to fungal infections in patients with neutropenia . Haas et al. (2013) found A. fumigatus , a common pathogen causing fungal pneumonia, in 52.8% of the 36 tea samples examined . It is therefore advised for immunosuppressed patients not to handle dry tea leaves themselves and only to infuse tea with boiling water. Due to the manufacturing process, this caution is particularly advisable with Pu-Erh.

A distinction must be made between the types of mold that are necessary for fermentation and those whose toxins can be harmful to human health. Li et al. (2015) showed average aflatoxin B 1 concentrations of 8,333 μg / kg in Sheng and 20,149 μg / kg in 30 representative samples of raw (sheng) and matured (shou) Pu-erh from five prefectures in Yunnan Province using HPLC in Shou-Pu-Erh. All measured values ​​were below the limit value of 5–20 µg / kg permitted in China, but significantly higher than the limit values ​​in the EU (2 µg / kg), USA and Japan (10 µg / kg). The authors of this study conclude that exposure to aflatoxin may prove to be a barrier to trade for the tea variety.

In the study by Haas et al. (2013), tea samples with a particularly high content of ochratoxin A (0.65, 14.8 and 94.7 μg / kg, [detection limit of the method: 0.5 μg / kg], EU limit value for coffee: 5 μg / kg) Penicillium species detected, but not A. acidus . The authors of the study suspect that the tea, which is particularly highly contaminated with toxins, may not have been fermented properly, so that the pathogenic species were able to grow preferentially during production. The concentrations in which the poorly water-soluble ochratoxin can be detected in the tea infusion was not investigated; the traditional recommendation to pour away the first infusion of the Pu-Erh (to "wash" the tea), however, seemed to the authors to be suitable for reducing the concentration of mold toxins in ready-to-drink tea. Proper storage of the tea also prevents colonization by harmful microorganisms.

A systematic chromosome analysis of the species involved in various fermentation processes in Asian food production led to the discovery of Aspergillus (A.) luchuensis and A. acidus . Despite proven colonization with A. acidus , the harmful toxins ochratoxin A and fumonisin B 2 produced by this species could not be detected in pu-erh and black tea. Black and pu-erh tea extracts can also inhibit the production of aflatoxins by A. flavus .

Based on these findings, research is currently being carried out into improving the fermentation process by optimizing the microflora involved.

literature

  • Jinghong Zhang: Puer tea: Ancient caravans and urban chic (=  Culture, Place, and Nature ). University of Washington Press, 2013, ISBN 978-0-295-99323-2 .

Web links

Commons : Pu-Erh  - collection of pictures, videos and audio files

Individual evidence

  1. ↑ a b James A. Benn: Tea in China. A religious and cultural history . University of Hawaii Press, Honolulu 2015, ISBN 978-0-8248-3964-2 , pp. 120 .
  2. ^ Jinghong Zhang: Puer tea: Ancient caravans and urban chic . University of Washington Press, 2013, ISBN 978-0-295-99323-2 , pp. 11 .
  3. ↑ James Lee: The Legacy of Immigration in Southwest China, 1250-1850 . In: Annals de demographie historique . 1982, p. 279–304 ( persee.fr [accessed March 4, 2018]).
  4. ^ C. Patterson Giersch: Asian borderlands: The transformation of Qing China's Yunnan frontier . Harvard University Press, Cambridge, Mass. 2006, ISBN 0-674-02171-1 , pp. 24-25 .
  5. ↑ FN Wachira, W. Powell, R. Waugh: An assessment of genetic diversity among Camellia sinensis L. (cultivated tea) and its wild relatives based on randomly amplified polymorphic DNA and organelle-specific STS . In: Heredity . tape 79 , 1997, pp. 603-611 .
  6. ↑ The traditional agro-system of Pu-Erh on fao.org , accessed March 3, 2018.
  7. ^ C. Long, J. Wang: Studies of traditional tea-garden of Jinuo nationality, China . In: SK Jain (Ed.): Ethno-biology in human welfare . Deep Publications, New Delhi 1996, ISBN 81-85622-05-1 , pp. 339-344 .
  8. ↑ Andrew Forbes, David Henley: Six Great Tea Mountains . In: China's Ancient Tea Horse Road (e-book) . Cognoscenti Books, Chiang Mai 2011.
  9. ^ Jinghong Zhang: Puer tea: Ancient caravans and urban chic . University of Washington Press, 2013, ISBN 978-0-295-99323-2 , pp. 36-38 .
  10. ↑ a b c Jinhong Zhang: Puer Tea: Ancient Caravans and Urban Chic . University of Washington Press, London / Seattle 2013, ISBN 978-0-295-99323-2 , Appendix 1: Puer Tea Categories and Production Process, p. 206 .
  11. ↑ YH Yang: The riddle of Pu-erh tea post-fermentation . In: Journal of Pu-erh . No. 2 , 2006, p. 80-85 .
  12. ↑ a b c M. Abe, N. Takaoka, Y. Idemoto, C. Takagi, T. Imai, K. Nakasaki: Characteristic fungi observed in the fermentation process for Puer tea . In: International Journal of Food Microbiology . No. 124 , 2008, p. 199-203 .
  13. ↑ Haizhen Mo, Yang Zhu, Zongmao Chen: Microbial fermented tea - a potential source of natural food preservatives . In: Trends in food science & technology . tape 19 , no. 3 , 2008, p. 124-130 .
  14. ↑ Kee-Ching Jeng: Effect of microbial fermentation on content of statin, GABA, and polyphenols in Pu-Erh tea . In: Journal of Agricultural and Food Chemistry . tape 55 , no. 21 , 2007, p. 8787-8792 , doi : 10.1021 / jf071629p , PMID 17880152 .
  15. ↑ Jia-shun Gong et al .: Changes of Chemical Components in Pu'er Tea Produced by Solid State Fermentation of Sundried Green Tea [J] . In: Journal of Tea Science . tape 25 , no. 4 , April 2005, p. 300-306 .
  16. ↑ Hong-Jie Zhou: Study on Main Microbes on Quality Formation of Yunnan Puer Tea during Pile-fermentation Process . In: Journal of Tea Science . tape 3 , 2004.
  17. ^ ZJ Zhao: Fungal colonization of Pu-Erh tea in Yunnan . In: Journal of food safety . tape 30 , no. 4 , 2010, p. 769–784 , doi : 10.1111 / j.1745-4565.2010.00240.x .
  18. ↑ Keke Chen et al .: Isolation and identification of Aspergillus species from the post fermentative process of Pu-Er ripe tea . In: Acta Botanica Yunnanica . tape 28 , no. 2 , 2005, p. 123-126 .
  19. ↑ a b Seung-Beom Hong et al: Aspergillus luchuensis, an industrially important black Aspergillus in East Asia . In: PLOS ONE . tape 8 , no. 5 , 2013, p. e63769 , doi : 10.1371 / journal.pone.0063769 .
  20. ↑ a b c J. M. Mogensen, J. Varga, U. Thrane, JC Frisvad: Aspergillus acidus from Puerh tea and black tea does not produce ochratoxin A and fumonisin B2 . In: International Journal of Food Microbiology . tape 132 , 2009, p. 141-144 , doi : 10.1016 / j.ijfoodmicro.2009.04.011 .
  21. ↑ Jinhong Zhang: Puer Tea: Ancient Caravans and Urban Chic . University of Washington Press, London / Seattle 2013, ISBN 978-0-295-99323-2 , Appendix 1: Puer Tea Categories and Production Process, p. 43 .
  22. ↑ Yang Liu, Shi-xiong Yang, Peng-zhang Ji, Li-zhi: Phylogeography of Camellia taliensis (Theaceae) inferred from chloroplast and nuclear DNA: Insights into evolutionary history and conservation . In: BMC Evolutionary Biology . tape 12 , 2012.
  23. ^ Zhang Yan: Hong Kong to hold its first rare tea auction. In: Financial Times. November 2013, accessed February 25, 2018 .
  24. ↑ a b c Wu De: Introduction to the three eras of Puerh Tea. (PDF) In: Global Tea Hut. October 2013, accessed February 25, 2018 .
  25. ↑ Menghai Tea Factory Pu-erh. Retrieved February 25, 2018 .
  26. ^ Joseph Needham: Tea processing and utilization . In: Huang-Tsing Tsung (Ed.): Science and Civilization of China . tape 6 , part 5: Fermentations and food science. Cambridge University Press , 2004, ISBN 0-521-65270-7 , pp. 561 ( monoskop.org [PDF; accessed on February 24, 2018]).
  27. ↑ Chi-Hua Lu, Lucy Sun Hwang: Polyphenol contents of Pu-Erh teas and their abilities to inhibit cholesterol biosynthesis in Hep G2 cell line . In: Food Chemistry . tape 111 , no. 1 , November 1, 2008, p. 67-71 , doi : 10.1016 / j.foodchem.2008.03.043 .
  28. ↑ Chun-Te Chiang, Meng-Shih Weng, Shoei-Yn Lin-Shiau, Kuan-Li Kuo, Yao-Jen Tsai, Jen-Kun Lin: Pu-erh tea supplementation suppresses fatty acid synthase expression in the rat liver through downregulating act and JNK signalings as demonstrated in human hepatoma HepG2 cells. In: Oncology research . tape 16 , no. 3 , 2005, p. 119-128 , PMID 16925113 .
  29. ↑ She-Ching Wu, Gow-Chin Yen, Bor-Sen Wang, Chih-Kwang Chiu, Wen-Jye Yen, Lee-Wen Chang, Pin-Der Duh: Antimutagenic and antimicrobial activities of pu-erh tea . In: LWT - Food Science and Technology . tape 40 , no. 3 , April 2007, p. 506-512 , doi : 10.1016 / j.lwt.2005.11.008 .
  30. ↑ L. Zhao, S. Jia, W. Tang, J. Sheng, Y. Luo: Pu-erh tea inhibits tumor cell growth by down-regulating mutant p. 53 . In: International Journal of Molecular Sciences . tape 12 , no. 11 , 2011, p. 7581-7593 .
  31. ↑ Kristin Surak: Nation work: A praxeology of making and maintaining nations . In: European Journal of Sociology . tape 53 , no. 2 , 2012, p. 171-204 , doi : 10.1017 / S0003975612000094 .
  32. ↑ Selena Ahmed, Uchenna Unachukwu, John Richard Stepp, Charles M. Peters, Chunlin Long, Edward Kennelly: Pu-erh tea tasting in Yunnan, China: Correlation of drinkers' perceptions to phytochemistry . In: Journal of Ethnopharmacology . tape 132 , no. 1 , 2010, p. 176-185 , doi : 10.1016 / j.jep.2010.08.016 .
  33. ↑ DGE: Pu-erh tea is not a miracle cure. ( Memento from January 23, 2009 in the Internet Archive ) October 4, 2000.
  34. ^ J. Cao, Y. Zhao, JW Liu: Safety evaluation and fluorine concentration of pu'er brick tea and bianxiao brick tea . In: Food and Chemical Toxicology . tape 36 , no. December 12 , 1998, pp. 1061-1063 , doi : 10.1016 / S0278-6915 (98) 00087-8 , PMID 9862647 .
  35. ↑ Jin Cao, Xuexin Bai, Yan Zhao, Jianwei Liu, Dingyou Zhou, Shiliang Fang, Ma Jia, Jinsheng Wu: The Relationship of Fluorosis and Brick Tea Drinking in Chinese Tibetans. In: Environmental Health Perspectives . Volume 104, No. 12, 1996.
  36. ↑ J. Cao, Y. Zhao, J. Liu: Brick tea consumption as the cause of dental fluorosis among children from Mongol, Kazak and Yugu populations in China. In: Food Chem. Toxicol. Volume 35, No. 8, 1997, pp. 827-833.
  37. ↑ F. Bourdichon et al .: Food fermentations: microorganisms with technological beneficial use . In: International Journal of Food Microbiology . tape 154 , no. 3 , 2012, p. 87-97 .
  38. ↑ a b c d Doris Haas, Bettina Pfeifer, Christoph Reiterich, Regina Partenheimer, Bernhard Reck, Walter Buzina: Identification and quantification of fungi and mycotoxins from Pu-erh tea . In: International Journal of Food Microbiology . tape 166 , no. 2 , 2013, p. 316–322 , doi : 10.1016 / j.ijfoodmicro.2013.07.024 ( semanticscholar.org [PDF; accessed on February 24, 2018]).
  39. ↑ AE Elshafie, T. Al-Lawatia, S. Al-Bahry: fungi associated with black tea and tea quality in the Sultanate of Oman . In: Mycopathologia . tape 145 , no. 2 , p. 89-93 .
  40. ↑ A. Bouakline, C. Lacroix, N. Roux, JP Gangneux, F. Derouin: Fungal contamination of food in hematology units . In: Journal of Clinical Microbiology . tape 38 , no. 11 , 2000, pp. 4272-4273 .
  41. ↑ RJ Manuel, CC Kibbler: The epidemiology and prevention of invasive aspergillosis . In: The Journal of Hospital Infection . tape 39 , no. 2 , 1998, p. 95-109 .
  42. ↑ Wengui Li, Kunlong Xu, Rong Xiao, Gefen Yin, Wenwen Liu: Development of an HPLC-based method for the detection of aflatoxins in Pu-erh tea . In: International Journal of Food Properties . tape 18 , no. 4 , 2015, p. 842-848 , doi : 10.1080 / 10942912.2014.885043 .
  43. ↑ AE Elshafie, T. Al-Lawatia, S. Al-Bahry: fungi associated with black tea and tea quality in the Sultanate of Oman . In: Mycopathologia . tape 145 , no. 2 , p. 89-93 .
  44. ↑ HZ Mo, H. Zhang, QH Wu, LB Hu: Inhibitory effects of tea extract on aflatoxin production by Aspergillus flavus . In: Letters in Applied Microbiology . 2013, doi : 10.1111 / j.1472-765X.2013.012073.x .
  45. ↑ Y. Chen, B.-L. Liu, Y.-N. Chang: Bioactivities and sensory evaluation of Pu-erh teas made from three tea leaves in an improved pile fermentation process . In: Journal of Bioscience and Bioengineering (6) . 2010, p. 557-563 .