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Black tea

Black tea (also literally translated as red tea from various East Asian languages) is a type of tea that is more oxidized than oolong, yellow, white and green teas. Black tea is generally stronger in flavour than other teas. All five types are made from leaves of the shrub (or small tree) Camellia sinensis, though Camellia taliensis is also used rarely.[2][3][4]

Two principal varieties of the species are used – the small-leaved Chinese variety plant (C. sinensis var. sinensis), used for most other types of teas, and the large-leaved Assamese plant (C. sinensis var. assamica), which was traditionally mainly used for black tea, although in recent years some green and white teas have been produced.

First originating in China, the beverage's name there is hong cha (Chinese: 紅茶, "red tea") due to the colour of the oxidized leaves when processed appropriately.[1] Today, the drink is widespread throughout East and Southeast Asia, both in consumption and harvesting, including in China, Japan, Korea and Singapore.[5] Similar variants are also available in South Asian countries.

While green tea usually loses its flavour within a year, black tea retains its flavour for several years. For this reason, it has long been an article of trade, and compressed bricks of black tea even served as a form of de facto currency in Mongolia, Tibet, and Siberia well into the 19th century.[6]

Varieties and names

Generally, unblended black teas are named after the region in which they are produced. Often, different regions are known for producing teas with characteristic flavours.

Blends

Many finished black teas consist of blends of various varieties of black tea. In addition, black tea is often blended with various other plants or flavourings in order to obtain a beverage.

Manufacture

Tea plantation in Java, Indonesia
  1. After the harvest, the leaves are first withered by blowing air on them.
  2. Then black teas are processed in either of two ways, CTC (crush, tear, curl) or orthodox. The CTC method produces leaves of fannings or dust grades that are commonly used in tea bags but also produces higher (broken leaf) grades such as BOP CTC and GFBOP CTC (see gradings below for more details). This method is efficient and effective for producing a better quality product from medium and lower quality leaves of consistently dark color. Orthodox processing is done either by machines or by hand. Hand processing is used for high quality teas. While the methods employed in orthodox processing differ by tea type, this style of processing results in the high quality loose tea sought by many connoisseurs. The tea leaves are allowed to completely oxidize.[13]
    Orthodox
    The withered tea leaves are heavily rolled either by hand or mechanically through the use of a cylindrical rolling table or a rotovane. The rolling table consists of a ridged table-top moving in an eccentric manner to a large hopper of tea leaves, in which the leaves are pressed down onto the table-top. The process produces a mixture of whole and broken leaves and particles which are then sorted, oxidized and dried. The rotorvane (rotovane), created by Ian McTear in 1957 can be used to replicate the orthodox process.[13] The rotovane consisted of an auger pushing withered tea leaves through a vane cylinder which crushes and evenly cuts the leaves, however the process is more recently superseded by the boruah continuous roller, which consists of an oscillating conical roller around the inside of a ridged cylinder.[13] The rotorvane can consistently duplicate broken orthodox processed black tea of even sized broken leaves, however it cannot produce whole leaf black tea.[14] The broken leaves and particles from the orthodox method can feed into the CTC method for further processing into fanning or dust grade teas.
    "Cut (or crush), tear, curl" (CTC)
    A production method developed by William McKercher in 1930. It is considered by some[who?] as a significantly improved method of producing black tea through the mincing of withered tea leaves.[15] The use of a rotovane to precut the withered tea is a common preprocessing method prior to feeding into the CTC.[13] CTC machines then further shred the leaves from the rotovane by passing them through several stages of contra-rotating rotors with surface patterns that cut and tear the leaves to very fine particles.[13]
  3. Next, the leaves are oxidized under controlled temperature and humidity. (This process is also called "fermentation", which is a misnomer since no actual fermentation takes place. Polyphenol oxidase is the enzyme active in the process.) The level of oxidation determines the type (or "color") of the tea; with fully oxidised becoming black tea, low oxidised becoming green tea, and partially oxidised making up the various levels of oolong tea.[16][17] This can be done on the floor in batches or on a conveyor bed with air flow for proper oxidation and temperature control. Since oxidation begins at the rolling stage itself, the time between these stages is also a crucial factor in the quality of the tea; however, fast processing of the tea leaves through continuous methods can effectively make this a separate step. The oxidation has an important effect on the taste of the end product,[17] but the amount of oxidation is not an indication of quality. Tea producers match oxidation levels to the teas they produce to give the desired end characteristics.
  4. Then the leaves are dried to arrest the oxidation process.
  5. Finally, the leaves are sorted into grades according to their sizes (whole leaf, brokens, fannings and dust), usually with the use of sieves. The tea could be further sub-graded according to other criteria.

The tea is then ready for packaging.

Tea grading

Black tea grading
Fresh tea leaves of different sizes

Black tea is usually graded on one of four scales of quality. Whole-leaf teas are the highest quality, with the best whole-leaf teas graded as "orange pekoe". After the whole-leaf teas, the scale degrades to broken leaves, fannings, then dusts. Whole-leaf teas are produced with little or no alteration to the tea leaf. This results in a finished product with a coarser texture than that of bagged teas. Whole-leaf teas are widely considered the most valuable, especially if they contain leaf tips. Broken leaves are commonly sold as medium-grade loose teas.

Smaller broken varieties may be included in tea bags. Fannings are usually small particles of tea left over from the production of larger tea varieties, but are occasionally manufactured specifically for use in bagged teas. Dusts are the finest particles of tea left over from production of the above varieties, and are often used for tea bags with very fast and harsh brews. Fannings and dusts are useful in bagged teas because the greater surface area of the many particles allows for a fast, complete diffusion of the tea into the water. Fannings and dusts usually have a darker colour, lack of sweetness, and stronger flavour when brewed.

Brewing

Black tea with spices

Generally, one uses 0.08 ounces (2.26 g) of tea per 8 US fl oz (237 ml) of water.[18] Unlike green teas, which turn bitter when brewed at higher temperatures, black tea should be steeped in water brought up to 212 °F (100 °C) for 3–5 min.[19]

Whole-leaf black teas, and black teas to be served with milk or lemon, should be steeped four to five minutes.[20] The more delicate black teas, such as Darjeeling, should be steeped for three to four minutes. The same holds for broken leaf teas, which have more surface area and need less brewing time than whole leaves. Longer steeping times makes the tea bitter (at this point, it is referred to as being "stewed" in the UK). When the tea has brewed long enough to suit the drinker's taste, it should be strained before it is served.

A cold vessel lowers the steep temperature; to avoid this, always rinse the vessel with ≥90 °C (≥194 °F) water before brewing.

The ISO Standard 3103 defines how to brew tea for tasting.[21] "This standard is not meant to define the proper method for brewing tea intended for general consumption, but rather to document a tea brewing procedure where meaningful sensory comparisons can be made." This mix is thus more than twice as concentrated for normal consumption.

ISO 3103 black tea brewing

Research

Plain black tea without sweeteners or additives contains 50 mg of caffeine per 250 mL cup,[22] but negligible quantities of calories or nutrients.[23] Black teas from Camellia sinensis contain polyphenols, such as flavonoids, which are under preliminary research for their potential to affect blood pressure and blood lipids as risk factors for cardiovascular disease,[24] but overall this research remains inconclusive.[23]

Long-term consumption of black tea only slightly lowered systolic and diastolic blood pressures (about 1–2 mmHg).[24][25] Black tea consumption may be associated with a reduced risk of stroke, but there is only limited research to evaluate this possibility.[26][27]

Meta-analyses of observational studies concluded that black tea consumption does not affect the development of oral cancers in Asian or Caucasian populations, esophageal cancer or prostate cancer in Asian populations, or lung cancer.[23][28][29][30]

The visible film often formed on black tea consists of oxidized polyphenols and calcium carbonate, and is therefore more pronounced for tea brewed with hard water.[31]

See also

Wikimedia Commons has media related to Black tea.

References

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  2. ^ "Laoshu Dianhong (Old Tree Yunnan)".
  3. ^ "Yunnan da Bai Silver Needles – Tea Trekker".
  4. ^ Liu et al. (2012)
  5. ^ Nanien, Yuniar; Aria, Cindyara; Sri, Haryati (14 November 2019). "Important to learn about Indonesian tea diversity: Expert". en.antaranews.com. Antara News. Retrieved 15 October 2021.
  6. ^ Bressett, Ken. "Tea Money of China". International Primitive Money Society Newsletter (44, August 2001).
  7. ^ "21 Extensive and Complete information on Darjeeling Tea". thunderbolttea.com. Retrieved 29 April 2019.
  8. ^ "Types of Tea & Different Tea Varieties in India – Assam, Darjeeling, Kangra & Nilgiri". Archived from the original on 26 January 2021. Retrieved 13 December 2016.
  9. ^ "Hadong Jaeksul Cha". Slow Food Foundation. Retrieved 23 June 2017.
  10. ^ Richardson, Ben (6 April 2006). "Bergamot growers get whiff of success". BBC News.
  11. ^ "Discovery Collection Orangery of Lady Grey - 15 Pyramid Tea Bags".
  12. ^ "India, the largest black tea consumer in the world". Archived from the original on 6 February 2018. Retrieved 5 January 2018.
  13. ^ a b c d e Varnam, Alan H.; Sutherland, J. M. (1994), Beverages:Technology, Chemistry and Microbiology, Springer
  14. ^ Heiss, Mary Lou; Heiss, Robert J. (2007), The story of tea: a cultural history and drinking guide, Random House
  15. ^ Harbowy, Matthew E.; Balentine, Douglas A.; Davies, Alan P.; Cai, Ya (1997), "Tea Chemistry", Critical Reviews in Plant Sciences, 16 (5): 415–480, Bibcode:1997CRvPS..16..415H, doi:10.1080/07352689709701956
  16. ^ "Black Tea Oxidization". Tin Roof Teas. Retrieved 23 August 2016.
  17. ^ a b "Oxidation of Tea - RateTea". Retrieved 13 December 2016.
  18. ^ "Black Tea".
  19. ^ "Lipton, Black Tea – SmartLabel™".
  20. ^ Upton Tea Imports, "A Brief Guide to Tea" (PDF). Archived from the original (PDF) on 23 November 2006. Retrieved 21 October 2006.
  21. ^ ISO3103, "ISO 3103 standard".
  22. ^ "FoodData Central". fdc.nal.usda.gov. Retrieved 16 May 2024.
  23. ^ a b c "Black tea: How effective is it?". MedlinePlus, US National Library of Medicine. 2015. Retrieved 15 March 2015.
  24. ^ a b Hartley L, Flowers N, Holmes J, Clarke A, Stranges S, Hooper L, Rees K (June 2013). "Green and black tea for the primary prevention of cardiovascular disease". Cochrane Database Syst Rev (Systematic Review and Meta-Analysis). 2013 (6): CD009934. doi:10.1002/14651858.CD009934.pub2. PMC 7433290. PMID 23780706.
  25. ^ Liu G, Mi XN, Zheng XX, Xu YL, Lu J, Huang XH (October 2014). "Effects of tea intake on blood pressure: a meta-analysis of randomised controlled trials". Br J Nutr (Meta-Analysis). 112 (7): 1043–54. doi:10.1017/S0007114514001731. PMID 25137341.
  26. ^ Shen L, Song LG, Ma H, Jin CN, Wang JA, Xiang MX (August 2012). "Tea consumption and risk of stroke: a dose-response meta-analysis of prospective studies". J Zhejiang Univ Sci B (Review). 13 (8): 652–62. doi:10.1631/jzus.B1201001. PMC 3411099. PMID 22843186.
  27. ^ Larsson SC (January 2014). "Coffee, tea, and cocoa and risk of stroke". Stroke (Review). 45 (1): 309–14. doi:10.1161/STROKEAHA.113.003131. PMID 24326448.
  28. ^ Wang W, Yang Y, Zhang W, Wu W (April 2014). "Association of tea consumption and the risk of oral cancer: a meta-analysis". Oral Oncol (Meta-Analysis). 50 (4): 276–81. doi:10.1016/j.oraloncology.2013.12.014. PMID 24389399.
  29. ^ Zheng J, Yang B, Huang T, Yu Y, Yang J, Li D (June 2011). "Green tea and black tea consumption and prostate cancer risk: an exploratory meta-analysis of observational studies". Nutr Cancer (Meta-Analysis). 63 (5): 663–72. doi:10.1080/01635581.2011.570895. PMID 21667398. S2CID 21567675.
  30. ^ Lin YW, Hu ZH, Wang X, Mao QQ, Qin J, Zheng XY, Xie LP (February 2014). "Tea consumption and prostate cancer: an updated meta-analysis". World J Surg Oncol (Meta-Analysis). 12: 38. doi:10.1186/1477-7819-12-38. PMC 3925323. PMID 24528523.
  31. ^ Giacomin, Caroline E.; Fischer, Peter (September 2021). "Black tea interfacial rheology and calcium carbonate". Physics of Fluids. 33 (9): 092105. Bibcode:2021PhFl...33i2105G. doi:10.1063/5.0059760. hdl:20.500.11850/505412. S2CID 239631952.