Fermented tea

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Fermented tea (simplified Chinese: 后发酵茶; traditional Chinese: 後發酵茶; pinyin: hòu fā jiào chá) 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 it to undergo endo-oxidation (derived from the tea-leaves enzymes themselves) and microbial catalysed, exo-oxidation. The resulting dark colour of the tea and its resulting liquor vary according to the level of oxidation achieved and thus, the various kinds of fermented teas produced across China are also commonly referred to as dark tea (Chinese: 黑茶; pinyin: hēichá; literally: "black tea"). They should not be confused with the black tea commonly referred in Western culture, which in East Asian cultures is called "red tea" (Chinese: 紅茶; pinyin: hóng chá). The most famous fermented tea is Pu-erh produced in Yunnan province. [1] [2]

The fermentation of tea leaves alters their essential chemistry affecting the organoleptic qualities of the resultant infused liquor. Fermentation affects the smell of the tea, and typically mellows its taste, turning previously astringent or bitter teas into products that are thick and unctuous, with pleasant a mouthfeel and aftertaste. The activities of the microbes involved may also produce metabolites with beneficial health properties [3] [4]

The fermentation process is predominantly carried out by various molds, with Aspergillus niger implicated as the main microbial organism. [5] [6] [7] This species identification has recently been challenged by comprehensive PCR-DGGE analysis, with researchers now renaming the species most commonly involved Aspergillus luchuensis, which does not produce toxins. [8] [9] [10] [11]

South Korea produces a fermented tea called Ddok Cha (떡차) and Japan produces two kinds of fermented tea called Awabancha (阿波番茶) and Goishicha (碁石茶). [12]

Varieties and producing areas[edit]

Dark tea is produced in many areas in China, but mostly restricted to the warmer Southern provinces. It is commonly pressed into bricks or cakes for aging. [13] [14]

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 (湖南黑茶 the famous Hua Zhuan 花砖 “flower brick”)
  • 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 Liu An Basket tea )
  • Sichuan: Liu Bian Cha (四川路边茶 Sichuan Border tea)
  • Hubei: Qing Zhuan Cha (湖北青砖茶 Hubei Green Brick tea)

Shapes include:

  • 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 specific to pu-erh
  • Squares, or "Fang Cha" (方茶)

Production[edit]

Many fermented teas do not arrive on the market as "finished" products; instead, they often start as green teas or partially oxidized oolong-like teas, which are then allowed to slowly oxidize and undergo microbial fermentation over many years, thus turning into fermented tea.[15] Alternatively, fermented teas can be created quickly through a ripening process spanning several months, as seen in ripened pu-erh. This ripening is done through a controlled process similar to composting, where both the moisture and temperature of the tea are carefully monitored. The resulting product from this fermentation is "finished" fermented tea.

Teas destined to be consumed as fermented teas are commonly sold as compressed tea of various shapes, including bricks, discs, bowls, or mushrooms.[16] Ripened pu-erh teas are ripened in loose form prior to compression. Fermented teas can be aged for many years to improve their flavor. In the case of raw pu-erh tea, it can be aged up to 30 to 50 years without diminishing in quality, and ripened pu-erh can be aged up to 10 to 15 years. However, experts and aficionados disagree about the optimal age to stop the aging process.

Many Tibetans and Central Asians use pu-erh or other fermented teas as a caloric food, boiled with yak butter, sugar and salt to make yak butter tea.

See also[edit]

References[edit]

  1. ^ 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.
  2. ^ Lv, Hai-peng, et al. "Processing and chemical constituents of Pu-erh tea: A review." Food Research International 53.2 (2013): 608-618.
  3. ^ 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.
  4. ^ 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.
  5. ^ 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.
  6. ^ Abe, Michiharu, et al. "Characteristic fungi observed in the fermentation process for Puer tea." International journal of food microbiology 124.2 (2008): 199-203.
  7. ^ 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.
  8. ^ Mogensen, Jesper Mølgaard, et al. " Aspergillus acidus from Puerh tea and black tea does not produce ochratoxin A and fumonisin B< sub> 2." International journal of food microbiology 132.2 (2009): 141-144.
  9. ^ Varga, J., et al. "New and revisited species in Aspergillus section Nigri." Studies in Mycology 69.1 (2011): 1-17.
  10. ^ 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.
  11. ^ Hong, Seung-Beom, et al. "Aspergillus luchuensis, an industrially important black Aspergillus in East Asia." PloS one 8.5 (2013): e63769.
  12. ^ http://www.worldoftea.org/post-fermented-tea-classification/
  13. ^ 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.
  14. ^ Lv, Hai-peng, et al. "Processing and chemical constituents of Pu-erh tea: A review." Food Research International 53.2 (2013): 608-618.
  15. ^ 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) 
  16. ^ Native Tastes Fermented Tea Production Methods and Processes "Methods and Processes"

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