Fermented tea (also known as post-fermented tea or dark tea) is a class of tea that has undergone microbial fermentation, from several months to many years. The exposure of the tea leaves to humidity and oxygen during the process also causes endo-oxidation (derived from the tea-leaf enzymes themselves) and exo-oxidation (which is microbially catalysed). The tea leaves and the liquor made from them become darker with oxidation. Thus, the various kinds of fermented teas produced across China are also referred to as dark tea, not be confused with black tea. The most famous fermented tea is kombucha which is often homebrewed, pu-erh, produced in Yunnan Province, and the Anhua dark tea produced in Anhua County of Hunan Province.
Golden Melon Pu-erh
|Literal meaning||Black/dark tea|
|Alternative Chinese name|
|Literal meaning||post-fermented tea|
|Hanyu Pinyin||hòu fājiào chá|
The fermentation of tea leaves alters their chemistry, affecting the organoleptic qualities of the tea made from them. Fermentation affects the smell of the tea and typically mellows its taste, reducing astringency and bitterness while improving mouthfeel and aftertaste. The microbes may also produce metabolites with health benefits.
The fermentation is carried out primarily by molds. Aspergillus niger was implicated as the main microbial organism in the Pu-erh process, but that species identification has been challenged by comprehensive PCR-DGGE analysis, which points to Aspergillus luchuensis as the primary agent of fermentation.
Most fermented teas are made in China, but several varieties are produced in Japan. In Shan State, Myanmar, lahpet is a form of fermented tea that is eaten as a vegetable, and similar pickled teas are also eaten in northern Thailand and southern Yunnan.
The early history of dark tea is unclear, but there are several legends and some credible theories.
For example, one legend holds that dark tea was first produced accidentally, on the Silk Road and Tea Road by tea caravans in the rainy season. When the tea was soaked in rain, the tea transporters abandoned it for fear of contamination. The next year, nearby villages suffered from dysentery, and decided to drink the abandoned mildewed tea in desperation. The legend concludes that the tea cured those suffering, and quickly became popular.
More historical accounts attribute the production of dark tea to the Ming Dynasty in the 15th and 16th centuries. It may have been first traded by tea merchants much earlier than the legends state, in areas on the borders of China and Tibet.
Fermented teas can be divided according to how they are produced. Piled teas, such as the Chinese post-fermented teas, and the Toyama kurocha produced in Japan, are fermented with naturally occurring fungus under relatively dry conditions. Other fermented teas, called pickled teas, are fermented in a wet process with lactic acid bacteria. Pickled teas include miang from Thailand and awabancha from Japan. A third category, including the Japanese Goishicha and Ishizuchi-kurocha, is fermented with the piled and pickling methods successively.
Fermented tea originates in China, where it is commonly known as hei cha (黑茶) or dark tea. Hei cha is produced in many areas of China, mostly in the warmer southern provinces. It is commonly pressed into bricks or cakes for ageing.
The most famous and important producing areas and varieties include:
- Yunnan: Pu-erh cha (雲南普洱茶, either "raw" Sheng Pu-erh 生普洱 or "ripened" Shu Pu-erh 熟普洱)
- Hunan: Fu Zhuan cha (湖南茯磚茶 (黑茶), the famous Fu Zhuan 茯磚茶 “brick tea”)
- Guangxi: Liu Bao cha (廣西六堡茶, often sold as 松黑茶, loose dark tea)
- Anhui: Liu An cha (安徽六安籃茶, Lu An basket tea )
- Sichuan: Lu Bian cha (四川路边茶, Sichuan border tea)
- Hubei: Qing Zhuan cha (湖北青砖茶, Hubei green brick tea)
- Tibet: Tibeti, brick tea or Zang cha (藏茶, Tibetan tea)
- Bamboo leaf logs
- Cakes, or "Bing cha" (餅茶)
- Bricks, or "Zhuan cha" (磚茶)
- Loose, in baskets
- Bird nests, or "Tuo cha" (沱茶), usually Pu-erh
- Squares, or "Fang cha" (方茶)
Kombucha (also tea mushroom, tea fungus, or Manchurian mushroom when referring to the culture; botanical name Medusomyces gisevii) is a fermented, slightly alcoholic, lightly effervescent, sweetened black or green tea drink commonly consumed for its supposed health benefits. Sometimes the beverage is called kombucha tea to distinguish it from the culture of bacteria and yeast. Juice, spices, fruit or other flavorings are often added to enhance the taste of the beverage.
Several distinct varieties of fermented tea are produced in Japan. Toyama prefecture's Kurocha is Japan's only piled tea, similar to the Chinese post-fermented teas. Toyama Kurocha is traditionally prepared by boiling in water, adding salt and stirring with a whisk as in a traditional tea ceremony. It is consumed on religious occasions or during meetings in the Asahi area of the prefecture. Awabancha (阿波番茶), produced in Tokushima prefecture, and Batabatacha, like the Toyama Kurocha associated with Asahi, Toyama, are made from bancha, or second flush tea leaves, with bacterial fermentation. Batabatacha has been found to contain Vitamin B12, but in insignificant amounts for human diets. Goishicha (碁石茶) from Ōtoyo, Kōchi and Ishizuchi-Kurocha grown at the foot of Mount Ishizuchi in Ehime prefecture are made by fermenting the tea in a two step process, first with aerobic fungi, then with anaerobic bacteria.
Tteokcha (떡차; lit. "cake tea"), also called byeongcha (병차; 餠茶; lit. "cake tea"), was the most commonly produced and consumed type of tea in pre-modern Korea. Pressed tea made into the shape of yeopjeon, the coins with holes, was called doncha (돈차; lit. "money tea"), jeoncha (전차; 錢茶; lit. "money tea"), or cheongtaejeon (청태전; 靑苔錢; lit. "green moss coin"). Borim-cha (보림차; 寶林茶) or Borim-baengmo-cha (보림백모차; 寶林白茅茶), named after its birthplace, the Borim temple in Jangheung, South Jeolla Province, is a popular tteokcha variety.
Edible pickled teaEdit
Though the early history of tea is unclear, it has been established that for centuries people have chewed tea leaves. Few peoples today continue to consume tea by chewing or eating. In northern Thailand, a pickled tea product called miang is chewed as a stimulant. Steamed tea leaves are kept pressed into sealed bamboo baskets until the anaerobic fermentation produces a compact cake with the desired flavor. The fermentation takes four to seven days for young leaves and about a year for mature leaves. Miang is related to the Thai and Lao street snack Miang kham.
A similar pickled tea is eaten by the Blang people of Xishuangbanna in Yunnan, China, on the border with Myanmar and Laos. The tea, known locally as miam and by the Chinese as Suancha (酸茶), is first packed into bamboo tubes, then buried and allowed to ferment before eating.
Many fermented teas do not arrive on the market ready for consumption. Instead, they may start as green teas or partially oxidized oolong-like teas, which are then allowed to slowly oxidize and undergo microbial fermentation over many years (comparable to wines that are sold to be aged in a cellar). Alternatively, fermented teas can be created quickly through a ripening process spanning several months, as with most Pu-erh. This ripening is done through a controlled process similar to composting, where the moisture and temperature of the tea are carefully monitored. The product is "finished" fermented tea.
Fermented teas are commonly sold as compressed tea of various shapes, including bricks, discs, bowls, or mushrooms. Ripened Pu-erh teas are ripened while loose, then compressed. Fermented teas can be aged for many years to improve their flavor, again comparable to wines. Raw Pu-erh tea can be aged up to 50 years in some cases without diminishing in quality, and ripened Pu-erh can be aged up to 10 or 15 years. Experts and aficionados disagree about the optimal age.
Ageing and storageEdit
Post-fermented tea usually gets more valuable with age. Dark tea is often aged in bamboo baskets, bamboo-leaf coverings, or in its original packaging.
Many varieties of dark tea are purposely aged in humid environments to promote the growth of certain fungi, often called "golden flowers" or "jin hua" (金花) because of the bright yellow color.
- Mo, Haizhen, Yang Zhu, and Zongmao Chen. "Microbial fermented tea–a potential source of natural food preservatives." Trends in food science & technology 19.3 (2008): 124-130.
- Lv, Hai-peng, et al. "Processing and chemical constituents of Pu-erh tea: A review." Food Research International 53.2 (2013): 608-618.
- Ling, Tie-Jun, et al. "New Triterpenoids and Other Constituents from a Special Microbial-Fermented Tea Fuzhuan Brick Tea." Journal of agricultural and food chemistry 58.8 (2010): 4945-4950.
- GONG, Jia-shun, et al. "Changes of Chemical Components in Pu'er Tea Produced by Solid State Fermentation of Sundried Green Tea [J]." Journal of Tea Science 4 (2005): 010.
- Abe, Michiharu, et al. "Characteristic fungi observed in the fermentation process for Puer tea." International journal of food microbiology 124.2 (2008): 199-203.
- Mogensen, Jesper Mølgaard, et al. " Aspergillus acidus from Puerh tea and black tea does not produce ochratoxin A and fumonisin B 2." International journal of food microbiology 132.2 (2009): 141-144.
- Varga, J., et al. "New and revisited species in Aspergillus section Nigri." Studies in Mycology 69.1 (2011): 1-17.
- Haas, Doris, et al. "Identification and quantification of fungi and mycotoxins from Pu-erh tea." International journal of food microbiology 166.2 (2013): 316-322.
- Hong, Seung-Beom, et al. "Aspergillus luchuensis, an industrially important black Aspergillus in East Asia." PLoS ONE 8.5 (2013): e63769.
- Hua-Fu Wang; Xiao-Qing You; Zong-Mao Chen (2002). Zhen, Yong-su (ed.). Tea: Bioactivity and Therapeutic Potential. Taylor & Francis. p. 104. Retrieved 11 August 2014.
- Yamamoto, Takehiko; Juneja, Lekh Raj; Chu, Djoin-Chi; Kim, Mujo, eds. (1997). Chemistry and Applications of Green Tea. CRC Press. p. 6. Retrieved 11 August 2014.
- Vicony Teas. "Dark Tea - Hei Cha". Retrieved 4 November 2012.
- Tea Net. "Hei Cha". Teanet.com. Archived from the original on 7 June 2012. Retrieved 4 November 2012.
- Organizing Committee of ISTS (1991). Proceedings of the International Symposium on Tea Science. p. 95.
- "Effect Of The Flavor Component The Pu-er Tea In Aging Period" (PDF). Retrieved 11 August 2014.
- Jayabalan, Rasu (21 June 2014). "A Review on Kombucha Tea—Microbiology, Composition, Fermentation, Beneficial Effects, Toxicity, and Tea Fungus". Comprehensive Reviews in Food Science and Food Safety. 13 (4): 538–550. doi:10.1111/1541-4337.12073.
- "A mug of kombucha for your health?". Mayo Clinic. Retrieved 2018-09-01.
- Kawakami, Michiko; Shibamoto, Takayuki (1991). "Volatile Constituents of Piled Tea: Toyama Kurocha" (PDF). Retrieved 11 August 2014.
- "Two Fermented Japanese Banchas". Archived from the original on 12 August 2014. Retrieved 11 August 2014.
- Raloff, Janet (January 28, 2004). "Bacteria Brew a B Vitamin Boost". Retrieved 11 August 2014.
- "Saijo City Sightseeing Information". Archived from the original on 12 August 2014. Retrieved 11 August 2014.
- Cheong, Kyoung; Cho, Hee-sun (2006). "The Customs of Ddeok-cha(lump tea) and Characteristics by Degrees of Fermentation". Journal of Korean Tea Society. 12 (3): 71.
- Jung, Seo-Kyeong (2015). "Historycity about Coastal inflow of tteok-tea to Jeon-nam". Journal of North-East Asian Cultures (in Korean). 42: 105–126.
- "Taste the slow life with these Korean food specialties". Korea JungAng Daily. 24 October 2010. Retrieved 20 March 2017.
- "doncha" 돈차. Standard Korean Language Dictionary. National Institute of Korean Language. Retrieved 20 March 2017.
- "jeoncha" 전차. Standard Korean Language Dictionary. National Institute of Korean Language. Retrieved 20 March 2017.
- "Don Tea". Slow Food Foundation. Retrieved 21 March 2017.
- "Borim Backmocha". Slow Food Foundation. Retrieved 21 March 2017.
- Mitscher, Lester A.; Dolby, Victoria (1998). The Green Tea Book: China's Fountain of Youth. Avery Publishing Group. p. 24. Retrieved 11 August 2014.
- Utilization of Tropical Foods: Sugars, Spices and Stimulants:. Food and Agriculture organization of the United Nations. 1989. pp. 55–56. ISBN 92-5-102837-0.
- David Thompson. Thai Food. Ten Speed Press (2002), p. 483. ISBN 978-1-58008-462-8.
- "Eating Tea and Masticating Betel". Xishuangbanna Tropical Botanical Gardens. Archived from the original on 24 January 2004. Retrieved 12 August 2014.
- Fasi, Jason. "Lao Man'e: a Bulang Village in Transformation" (PDF). p. 3. Retrieved 12 August 2014.
- 溫, 志杰; 張, 凌云; 吳, 平; 何, 勇強 (2010), "黑茶加工中微生物作用的研究", 茶葉通訊 "TEA COMMUNICATION", 37 (2)
- Native Tastes Fermented Tea Production Methods and Processes "Methods and Processes" Archived 2014-02-03 at the Wayback Machine
- "Hei Cha". Dark Tea. Chawang Shop. Retrieved 4 November 2012.
- (in French) Le Monde du Thé - Black Teas.