Tea

Origin and history

Botanical origin

Tea plants are native to East Asia and the probable center of origin of tea is near the source of the Irrawaddy River from where it spread out fan-wise into southeast China, Indo-China and Assam. Thus, the natural home of the tea plant is considered to be within the comparatively small fan-shaped area between Nagaland, Manipur and Mizoram along the Burma frontier in the west, through China as far as the Zhejiang Province in the east, and from this line generally south through the hills to Burma and Thailand to Vietnam. The west–east axis indicated above is about 2,400 km long extending from longitude 95°-120°E. The north–south axis covers about 1,920 km, starting from the northern part of Burma, latitude 29°N passing through Yunnan, Tongkin, Thailand, Laos and on to Annan, reaching latitude 11°N.^[17]

Chinese (small-leaf) type tea (C. sinensis var. sinensis) may have originated in southern China possibly with hybridization of unknown wild tea relatives. However, since there are no known wild populations of this tea, its origin is speculative.^[18][19]

Given their genetic differences forming distinct

Assuming a generation of 12 years, Chinese small-leaf tea is estimated to have diverged from Assam tea around 22,000 years ago, while Chinese Assam tea and Indian Assam tea diverged 2,800 years ago. The divergence of Chinese small-leaf tea and Assam tea would correspond to the last glacial maximum.^[18][19]

Early tea drinking

People in ancient East Asia ate tea for centuries, perhaps even

Tea drinking may have begun in the region of Yunnan during the Shang dynasty, where it was used for medicinal purposes. It is also believed that in Sichuan, "people began to boil tea leaves for consumption into a concentrated liquid without the addition of other leaves or herbs, thereby using tea as a bitter yet stimulating drink, rather than as a medicinal concoction."^[5]

Chinese legends attribute the invention of tea to the mythical

The earliest known physical evidence[25] of tea was discovered in 2016 in the mausoleum of Emperor Jing of Han in Xi'an, indicating that tea from the genus Camellia was drunk by Han dynasty emperors as early as the second century BC.^[26] The Han dynasty work "The Contract for a Youth", written by Wang Bao in 59 BC,^[27] contains the first known reference to boiling tea. Among the tasks listed to be undertaken by the youth, the contract states that "he shall boil tea and fill the utensils" and "he shall buy tea at Wuyang".^[2] The first record of tea cultivation is also dated to this period, during which tea was cultivated on Meng Mountain (蒙山) near Chengdu.^[28] Another early credible record of tea drinking dates to the 3rd century AD, in a medical text by the Chinese physician Hua Tuo, who stated, "to drink bitter t'u constantly makes one think better."^[29] However, before the Tang dynasty, tea-drinking was primarily a southern Chinese practice centered in Jiankang.^[30] Tea was disdained by the Northern dynasties aristocrats, who describe it as inferior to yogurt.^[31][32] It became widely popular during the Tang dynasty, when it also spread to Korea, Japan, and Vietnam. The Classic of Tea, a treatise on tea and its preparations, was written by the 8th century Chinese writer, Lu Yu. He was known to have influenced tea drinking on a large part in China.^{[33][unreliable source?]}

Developments

Through the centuries, a variety of techniques for processing tea, and a number of different forms of tea, were developed. During the Tang dynasty, tea was steamed, then pounded and shaped into cake form,^[34] while in the Song dynasty, loose-leaf tea was developed and became popular. During the Yuan and Ming dynasties, unoxidized tea leaves were first stirred in a hot dry pan, then rolled and air-dried, a process that stops the oxidation process that would have turned the leaves dark, thereby allowing tea to remain green. In the 15th century, oolong tea, in which the leaves are allowed to partially oxidize before being heated in the pan, was developed.^[30] Western tastes, however, favoured the fully oxidized black tea, and the leaves were allowed to oxidize further. Yellow tea was an accidental discovery in the production of green tea during the Ming dynasty, when apparently careless practices allowed the leaves to turn yellow, which yielded a different flavour.^[35]

Worldwide spread

Tea was first introduced to Western priests and merchants in China during the 16th century, at which time it was termed chá.^[13] The earliest European reference to tea, written as chiai, came from Delle navigationi e viaggi written by Venetian Giambattista Ramusio in 1545.^[36] The first recorded shipment of tea by a European nation was in 1607 when the Dutch East India Company moved a cargo of tea from Macao to Java, then two years later, the Dutch bought the first assignment of tea which was from Hirado in Japan to be shipped to Europe.^[37] Tea became a fashionable drink in The Hague in the Netherlands, and the Dutch introduced the drink to Germany, France, and across the Atlantic to New Amsterdam (New York).^[38]

In 1567, Russian people came in contact with tea when the Cossack Atamans Petrov and Yalyshev visited China.^[39] The Mongolian Khan donated to Tsar Michael I four poods (65–70 kg) of tea in 1638.^[40] According to Jeremiah Curtin,^[41] it was possibly in 1636^[42] that Vassili Starkov was sent as envoy to the Altyn Khan. He was given 250 pounds of tea as a gift to the tsar. Starkov at first refused, seeing no use for a load of dead leaves, but the Khan insisted. Thus was tea introduced to Russia. In 1679, Russia concluded a treaty on regular tea supplies from China via camel caravan in exchange for furs. It is today considered the de facto national beverage.

The first record of tea in English came from a letter written by Richard Wickham, who ran an East India Company office in Japan, writing to a merchant in Macao requesting "the best sort of chaw" in 1615. Peter Mundy, a traveller and merchant who came across tea in Fujian in 1637, wrote, "chaa – only water with a kind of herb boyled in it".^[43][44] Tea was sold in a coffee house in London in 1657, Samuel Pepys tasted tea in 1660, and Catherine of Braganza took the tea-drinking habit to the English court when she married Charles II in 1662. Tea, however, was not widely consumed in the British Isles until the 18th century and remained expensive until the latter part of that period. English drinkers preferred to add sugar and milk to black tea, and black tea overtook green tea in popularity in the 1720s.^[45] Tea smuggling during the 18th century led to the general public being able to afford and consume tea. The British government removed the tax on tea, thereby eliminating the smuggling trade, by 1785.^[46] In Britain and Ireland, tea was initially consumed as a luxury item on special occasions, such as religious festivals, wakes, and domestic work gatherings. The price of tea in Europe fell steadily during the 19th century, especially after Indian tea began to arrive in large quantities; by the late 19th century tea had become an everyday beverage for all levels of society.^[47] The popularity of tea played a role in historical events – the Tea Act of 1773 provoked the Boston Tea Party that escalated into the American Revolution. The need to address the issue of British trade deficit because of the trade in tea resulted in the Opium Wars. The Qing Kangxi Emperor had banned foreign products from being sold in China, decreeing in 1685 that all goods bought from China must be paid for in silver coin or bullion.^[48] Traders from other nations then sought to find another product, in this case opium, to sell to China to earn back the silver they were required to pay for tea and other commodities. The subsequent attempts by the Chinese Government to curtail the trade in opium led to war.^[49]

Chinese small-leaf-type tea was introduced into India in 1836 by the British in an attempt to break the Chinese monopoly on tea.

Physically speaking, tea has properties of both a solution and a suspension. It is a solution of all the water-soluble compounds that have been extracted from the tea leaves, such as the polyphenols and amino acids, but is a suspension when all of the insoluble components are considered, such as the cellulose in the tea leaves.^{[citation needed]} Tea infusions are among most consumed beverages globally.^[54]

Caffeine makes up about 3% of tea's dry weight, which translates to between 30 and 90 milligrams per 250-millilitre (8+1⁄2 US fl oz) cup depending on the type, brand,^[55] and brewing method.^[56] A study found that the caffeine content of one gram of black tea ranged from 22 to 28 mg, while the caffeine content of one gram of green tea ranged from 11 to 20 mg, reflecting a significant difference.^[57] Tea also contains small amounts of theobromine and theophylline, which are xanthines and stimulants, similar to caffeine.^[58]

The astringency in tea can be attributed to the presence of polyphenols. These are the most abundant compounds in tea leaves, making up 30–40% of their composition.^[59] Polyphenols in tea include flavonoids, epigallocatechin gallate (EGCG), and other catechins.^[60][61] Although there has been preliminary clinical research on whether green or black teas may protect against various human diseases, there is no evidence that tea polyphenols have any effect on health or lowering disease risk.^[62][63]

Health effects

Although health benefits have been assumed throughout the history of Camellia sinensis's consumption, there is no high-quality evidence showing that tea consumption gives significant benefits other than possibly increasing alertness, an effect caused by caffeine in the tea leaves.^[64][65] In clinical research conducted in the early 21st century, it was found there is no scientific evidence to indicate that consuming tea affects any disease or improves health.^[64]

Black and green teas contain no essential nutrients in significant amounts, with the exception of the dietary mineral manganese, at 0.5 mg per cup or 26% of the Reference Daily Intake (RDI).^[66] Fluoride is sometimes present in tea; certain types of "brick tea", made from old leaves and stems, have the highest levels, enough to pose a health risk if much tea is drunk, which has been attributed to high levels of fluoride in soils, acidic soils, and long brewing.^[67]

Cultivation and harvesting

Camellia sinensis is an evergreen plant that grows mainly in tropical and subtropical climates.^[68] Some varieties can also tolerate marine climates and are cultivated as far north as Cornwall in England,^[69] Perthshire in Scotland,^[70] Washington in the United States,^[71] and Vancouver Island in Canada.^[72] In the Southern Hemisphere, tea is grown as far south as Hobart in Tasmania^[73][74] and Waikato in New Zealand.^[75]

Tea plants are propagated from seed and cuttings; about 4 to 12 years are needed for a plant to bear seed and about three years before a new plant is ready for harvesting.^[68] In addition to a zone 8 climate or warmer, tea plants require at least 127 cm (50 in) of rainfall per year and prefer acidic soils.^[76] Many high-quality tea plants are cultivated at elevations of up to 1,500 m (4,900 ft) above sea level. Though at these heights the plants grow more slowly, they acquire a better flavour.^[77]

Two principal varieties are used: Camellia sinensis var. sinensis, which is used for most Chinese, Formosan and Japanese teas, and C. sinensis var. assamica, used in Pu-erh and most Indian teas (but not Darjeeling). Within these botanical varieties, many strains and modern clonal varieties are known. Leaf size is the chief criterion for the classification of tea plants, with three primary classifications being:^[78] Assam type, characterised by the largest leaves; China type, characterised by the smallest leaves; and Cambodian type, characterised by leaves of intermediate size. The Cambodian-type tea (C. assamica subsp. lasiocaly) was originally considered a type of Assam tea. However, later genetic work showed that it is a hybrid between Chinese small-leaf tea and Assam-type tea.^[79] Darjeeling tea also appears to be a hybrid between Chinese small-leaf tea and Assam-type large-leaf tea.^[19]

A tea plant will grow into a tree of up to 16 m (52 ft) if left undisturbed,^[68] but cultivated plants are generally pruned to waist height for ease of plucking. Also, the short plants bear more new shoots which provide new and tender leaves and increase the quality of the tea.^[80] Only the top 2.5–5 centimetres (1–2 in) of the mature plant are picked. These buds and leaves are called 'flushes'.^[81] A plant will grow a new flush every 7 to 15 days during the growing season. Leaves that are slow in development tend to produce better-flavoured teas.^[68] Several teas are available from specified flushes; for example, Darjeeling tea is available as first flush (at a premium price), second flush, monsoon and autumn. Assam second flush or "tippy" tea is considered superior to first flush, because of the gold tips that appear on the leaves.

Pests that can afflict tea plants include mosquito bugs, genus Helopeltis, which are true bugs and not to be confused with dipterous insects of family Culicidae ('mosquitos'). Mosquito bugs can damage leaves both by sucking plant materials, and by the laying of eggs (oviposition) within the plant. Spraying with synthetic insecticides may be deemed appropriate.^[82] Other pests are Lepidopteran leaf feeders and various tea diseases.

Production

Tea production – 2020

Country	Million tonnes
China	2.97
India	1.2
Kenya	0.43
Sri Lanka	0.34
Vietnam	0.214
Turkey	0.212
Iran	0.16
Indonesia	0.14
Argentina	0.10
Japan	0.08
Source: Worldatlas[83]

Tea is mainly grown in Asia and Africa, though it is also grown in South America and around the Black and Caspian Seas. The four biggest tea-producing countries are China, India, Kenya and Sri Lanka, together representing 75% of world tea production. Smaller hubs of production include such places as

Storage life for all teas can be extended by using desiccant or oxygen-absorbing packets, vacuum sealing, or refrigeration in air-tight containers (except green tea, where discrete use of refrigeration or freezing is recommended and temperature variation kept to a minimum).^[85]

Tea is generally divided into categories based on how it is processed.^[86] At least six different types are produced:

• White: wilted and unoxidized;
• Yellow: unwilted and unoxidized but allowed to yellow;
• Green: unwilted and unoxidized;
• Oolong: wilted, bruised, and partially oxidized;
• Black: wilted, sometimes crushed, and fully oxidized (called 紅茶 [hóngchá], "red tea" in Chinese and other East Asian tea culture);
• Post-fermented (Dark): green tea that has been allowed to ferment/compost (called Pu'er if from the Yunnan district of South-Western China or 黑茶 [hēichá] "black tea" in Chinese tea culture).

After picking, the leaves of C. sinensis soon begin to wilt and oxidize unless immediately dried. An enzymatic oxidation process triggered by the plant's intracellular enzymes causes the leaves to turn progressively darker as their chlorophyll breaks down and tannins are released. This darkening is stopped at a predetermined stage by heating, which deactivates the enzymes responsible. In the production of black teas, halting by heating is carried out simultaneously with drying. Without careful moisture and temperature control during manufacture and packaging, growth of undesired molds and bacteria may make tea unfit for consumption.

Additional processing and additives

After basic processing, teas may be altered through additional processing steps before being sold^[87] and is often consumed with additions to the basic tea leaf and water added during preparation or drinking. Examples of additional processing steps that occur before tea is sold are blending, flavouring, scenting, and decaffeination of teas. Examples of additions added at the point of consumption include milk, sugar and lemon.

Tea blending is the combination of different teas together to achieve the final product. Such teas may combine others from the same cultivation area or several different ones. The aim is to obtain consistency, better taste, higher price, or some combination of the three.

Flavoured and scented teas add aromas and flavours to the base tea. This can be accomplished through directly adding flavouring agents, such as ginger, cloves, mint leaves, cardamom, bergamot (found in Earl Grey), vanilla, and spearmint. Alternatively, because tea easily retains odours, it can be placed in proximity to an aromatic ingredient to absorb its aroma, as in traditional jasmine tea.^[88]

The addition of milk to tea in Europe was first mentioned in 1680 by the epistolist

In 1907, American tea merchant Thomas Sullivan began distributing samples of his tea in small bags of silk with a drawstring. Consumers noticed they could simply leave the tea in the bag and reuse it with fresh tea. However, the potential of this distribution and packaging method would not be fully realised until later. During World War II, tea was rationed in the United Kingdom. In 1953, after

The "pyramid tea bag" (or sachet), introduced by Lipton[97] and PG Tips/Scottish Blend in 1996,^[98] attempts to address one of the connoisseurs' arguments against paper tea bags by way of its three-dimensional tetrahedron shape, which allows more room for tea leaves to expand while steeping.^{[citation needed][99]} However, some types of pyramid tea bags have been criticised as being environmentally unfriendly, since their synthetic material is not as biodegradable as loose tea leaves and paper tea bags.^[100]

Loose tea

The tea leaves are packaged loosely in a canister, paper bag, or other container such as a tea chest. Some whole teas, such as rolled gunpowder tea leaves, which resist crumbling, are vacuum-packed for freshness in aluminised packaging for storage and retail. The loose tea is individually measured for use, allowing for flexibility and flavour control at the expense of convenience. Strainers, tea balls, tea presses, filtered teapots, and infusion bags prevent loose leaves from floating in the tea and over-brewing. A traditional method uses a three-piece lidded teacup called a gaiwan, the lid of which is tilted to decant the tea into a different cup for consumption.

Compressed tea

Compressed tea was the most popular form of tea in China during the Tang dynasty.[103] By the beginning of the Ming dynasty, it had been displaced by loose-leaf tea.^[104] It remains popular, however, in the Himalayan countries and Mongolian steppes. In Mongolia, tea bricks were ubiquitous enough to be used as a form of currency. Among Himalayan peoples, compressed tea is consumed by combining it with yak butter and salt to produce butter tea.^[105]

Instant tea

"Instant tea", similar to freeze-dried instant coffee and an alternative to brewed tea, can be consumed either hot or cold. Instant tea was developed in the 1930s, with Nestlé introducing the first commercial product in 1946, while Redi-Tea debuted instant iced tea in 1953. Additives such as chai, vanilla, honey or fruit, are popular, as is powdered milk.

During the Second World War British and Canadian soldiers were issued an instant tea known as "compo" in their composite ration packs. These blocks of instant tea, powdered milk, and sugar were not always well received. As Royal Canadian Artillery Gunner, George C Blackburn observed:

But, unquestionably, the feature of Compo rations destined to be remembered beyond all others is Compo tea...Directions say to "sprinkle powder on heated water and bring to the boil, stirring well, three heaped teaspoons to one pint of water." Every possible variation in the preparation of this tea was tried, but...it always ended up the same way. While still too hot to drink, it is a good-looking cup of strong tea. Even when it becomes just cool enough to be sipped gingerly, it is still a good-tasting cup of tea, if you like your tea strong and sweet. But let it cool enough to be quaffed and enjoyed, and your lips will be coated with a sticky scum that forms across the surface, which if left undisturbed will become a leathery membrane that can be wound around your finger and flipped away...^[106]

Bottled and canned tea

Canned tea is sold prepared and ready to drink. It was introduced in 1981 in Japan. The first bottled tea was introduced by an Indonesian tea company, PT. Sinar Sosro in 1969 with the brand name Teh Botol Sosro (or Sosro bottled tea).^[107] In 1983, Swiss-based Bischofszell Food Ltd. was the first company to bottle iced tea on an industrial scale.^[108]

Tea culture

Tea is the second most consumed beverage on Earth, after water. In many cultures it is consumed at elevated social events, such as the

In the United Kingdom, 63% of people drink tea daily.^[109] It is customary for a host to offer tea to guests soon after their arrival. Tea is consumed both at home and outside the home, often in cafés or tea rooms. Afternoon tea with cakes on fine porcelain is a cultural stereotype. In southwest England, many cafés serve a cream tea, consisting of scones, clotted cream, and jam alongside a pot of tea. In some parts of Britain and India, 'tea' may also refer to the evening meal.

Ireland, as of 2016, was the second-biggest per capita consumer of tea in the world, after Turkey.^[110] Local blends are the most popular in Ireland, including Irish breakfast tea, using Rwandan, Kenyan and Assam teas. The annual national average of tea consumption in Ireland is 2.7 kg to 4 kg per person. Tea in Ireland is usually taken with milk or sugar and brewed longer for a stronger taste.^[111]

Turkish tea is an important part of that country's cuisine and is the most commonly consumed hot drink, despite the country's long history of coffee consumption. In 2004, Turkey produced 205,500 tonnes of tea (6.4% of the world's total tea production), which made it one of the largest tea markets in the world,^[112] with 120,000 tons being consumed in Turkey and the rest being exported.^[113] In 2010, Turkey had the highest per capita consumption in the world at 2.7 kg.^[114] As of 2013, the per-capita consumption of Turkish tea exceeds 10 cups per day and 13.8 kg per year.^[115] Tea is grown mostly in Rize Province on the Black Sea coast.^[116]

In Pakistan, both black and green teas are popular and are known locally as sabz chai and kahwah, respectively. The popular green tea is often served after every meal in the Pashtun belt of Balochistan and in Khyber Pakhtunkhwa. In central and southern Punjab and the metropolitan Sindh region of Pakistan, tea with milk and sugar (sometimes with pistachios, cardamom, etc.), commonly referred to as chai, is widely consumed. It is the most common beverage of households in the region. In the northern Pakistani regions of Chitral and Gilgit-Baltistan, a salty, buttered Tibetan-style tea is consumed.

Indian tea culture is strong; the drink is the most popular hot beverage in the country. It is consumed daily^[118] in almost all houses, offered to guests, consumed in high amounts in domestic and official surroundings, and is made with the addition of milk with or without spices, and usually sweetened. It is sometimes served with biscuits to be dipped in the tea and eaten before consuming the tea. More often than not, it is drunk in "doses" of small cups (referred to as "cutting" chai if sold at street tea vendors) rather than one large cup.

Iranians have one of the highest per capita rates of tea consumption in the world. Châikhânes (teahouses) are common in Iran.^[119] Iranian tea is typically served in traditional Iranian glasses with a traditional saucer and teaspoon. Tea is cultivated in northern Iran along the shores of the Caspian Sea.^[120]

In Burma (Myanmar), tea is consumed not only as hot drinks, but also as sweet tea and green tea known locally as laphet-yay and laphet-yay-gyan, respectively. Pickled tea leaves, known locally as lahpet, are also a national delicacy. Pickled tea is usually eaten with roasted sesame seeds, crispy fried beans, roasted peanuts and fried garlic chips.^[121]

In Mali, gunpowder tea is served in series of three, starting with the highest oxidisation or strongest, unsweetened tea, locally referred to as "strong like death", followed by a second serving, where the same tea leaves are boiled again with some sugar added ("pleasant as life"), and a third one, where the same tea leaves are boiled for the third time with yet more sugar added ("sweet as love"). Green tea is the central ingredient of a distinctly Malian custom, the "Grin", an informal social gathering that cuts across social and economic lines, starting in front of family compound gates in the afternoons and extending late into the night, and is widely popular in Bamako and other large urban areas.^{[citation needed]}

In the United States, 80% of tea is consumed as iced tea.^[122] Sweet tea is native to the southeastern U.S. and is iconic in its cuisine.^[123]

• 
  Turkish tea

  served in a typical small glass and corresponding plate
• 
  English teaware
• 
  Iced tea with a slice of lemon
• 
  Indian masala tea

Economics

Tea is the most popular manufactured drink consumed in the world, equaling all others – including coffee, soft drinks, and alcohol – combined.^[9] Most tea consumed outside East Asia is produced on large plantations in the hilly regions of India and Sri Lanka and is destined to be sold to large businesses. Opposite this large-scale industrial production are many small "gardens," sometimes minuscule plantations, that produce highly sought-after teas prized by gourmets. These teas are both rare and expensive and can be compared to some of the most expensive wines in this respect.

India is the world's largest tea-drinking nation,^[124] although the per capita consumption of tea remains a modest 750 grams (26 oz) per person every year. Turkey, with 2.5 kilograms (5 lb 8 oz) of tea consumed per person per year, is the world's greatest per capita consumer.^[125]

Labor and consumer safety problems

Tests of commercially popular teas have detected residues of banned toxic pesticides.^[126][127]

Tea production in Kenya, Malawi, Rwanda, Tanzania, and Uganda has been reported to make use of

Production of organic tea has risen since its introduction in 1990 at Rembeng, Kondoli Tea Estate, Assam.^[131] 6,000 tons of organic tea were sold in 1999.^[132]

See also

• Other drinks:
  • Cannabis tea
  • Chifir'
    , Russian extra-strong tea brew
  • Herbal tea
  • Kombucha, drink produced from bacteria and yeast grown on tea
  • List of Chinese teas
  • List of hot beverages
  • List of national drinks
  • Mushroom tea
• Frederick John Horniman
• Indian Tea Association
• International Tea Day
• ISO 3103, a standardized method for brewing tea
• List of tea companies
• Phenolic content in tea
• Tea classics, influential historical monographs of East Asian tea
• Tea leaf grading
• Tea strainer
• Tea tasting
• Tea in France

References

Citations