Tea

Tea plants are native to East Asia, and probably originated in the borderlands of north Burma and southwestern China.[28]

• Chinese (small leaf) tea
• Chinese Western Yunnan Assam (large leaf) tea
  • Indian Assam (large leaf) tea
• Chinese Southern Yunnan Assam (large leaf) tea

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, the precise location of its origin is speculative.[29][30]

Given their genetic differences forming distinct clades, Chinese Assam type tea (C. sinensis var. assamica) may have two different parentages – one being found in southern Yunnan (Xishuangbanna, Pu'er City) and the other in western Yunnan (Lincang, Baoshan). Many types of Southern Yunnan assam tea have been hybridized with the closely related species Camellia taliensis. Unlike Southern Yunnan Assam tea, Western Yunnan Assam tea shares many genetic similarities with Indian Assam type tea (also C. sinensis var. assamica). Thus, Western Yunnan Assam tea and Indian Assam tea both may have originated from the same parent plant in the area where southwestern China, Indo-Burma, and Tibet meet. However, as the Indian Assam tea shares no haplotypes with Western Yunnan Assam tea, Indian Assam tea is likely to have originated from an independent domestication. Some Indian Assam tea appears to have hybridized with the species Camellia pubicosta.[29][30]

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.[29][30]

A 19th-century Japanese painting depicting Shennong: Chinese legends credit Shennong with the invention of tea.[31]

Tea drinking may have begun in the region of Yunnan region, when 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."[7]

Chinese legends attribute the invention of tea to the mythical Shennong (in central and northern China) in 2737 BC although evidence suggests that tea drinking may have been introduced from the southwest of China (Sichuan/Yunnan area).[31] The earliest written records of tea come from China. The word tú 荼 appears in the Shijing and other ancient texts to signify a kind of "bitter vegetable" (苦菜), and it is possible that it referred to many different plants such as sowthistle, chicory, or smartweed,[32] as well as tea.[16] In the Chronicles of Huayang, it was recorded that the Ba people in Sichuan presented tu to the Zhou king. The Qin later conquered the state of Ba and its neighbour Shu, and according to the 17th century scholar Gu Yanwu who wrote in Ri Zhi Lu (日知錄): "It was after the Qin had taken Shu that they learned how to drink tea."[2] Another possible early reference to tea is found in a letter written by the Qin Dynasty general Liu Kun who requested that some "real tea" to be sent to him.[33]

The earliest known physical evidence[34] 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 2nd century BC.[35] The Han dynasty work, "The Contract for a Youth", written by Wang Bao in 59 BC,[36] 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 (the reign of Emperor Xuan of Han), during which tea was cultivated on Meng Mountain (蒙山) near Chengdu.[37] Another early credible record of tea drinking dates to the third century AD, in a medical text by Hua Tuo, who stated, "to drink bitter t'u constantly makes one think better."[38] However, before the mid-8th century Tang dynasty, tea-drinking was primarily a southern Chinese practice[39] while the main drink in northern China was yogurt. Tea was disdained by the Northern dynasties aristocrats of the Central Plains, who describe it as a "slaves' drink", inferior to yogurt.[40][41] It became widely popular during the Tang Dynasty, when it was spread to Korea, Japan, and Vietnam. The Classic of Tea, a treatise on tea and its preparations, was written by Lu Yu in 762.

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,[42] while in the Song dynasty, loose-leaf tea was developed and became popular. During the Yuan and Ming dynasties, unoxidized tea leaves were first pan-fried, then rolled and dried, a process that stops the oxidation process that turns the leaves dark, thereby allowing tea to remain green. In the 15th century, oolong tea, in which the leaves were allowed to partially oxidize before pan-frying, was developed.[39] 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 sloppy practices allowed the leaves to turn yellow, but yielded a different flavour as a result.[43]

Tea-weighing station north of Batumi, Russian Empire before 1915

Tea was first introduced to Western priests and merchants in China during the 16th century, at which time it was termed chá.[9] The earliest European reference to tea, written as Chiai, came from Delle navigationi e viaggi written by a Venetian, Giambattista Ramusio, in 1545.[44] 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.[45] 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).[46]

In 1567, Russian people came in contact with tea when the Cossack Atamans Petrov and Yalyshev visited China.[47] In 1638 the Mongolian Khan donated to Tsar Michael I four poods (65–70 kg) of tea.[48] According to Jeremiah Curtin,[49] it was possibly in 1636[50] that Vassili Starkov was sent as envoy to the Altyn Khan. As a gift to the Tsar, he was given 250 pounds of tea. 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 ".[51][52] 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.[53] 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.[54] 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.[55] The popularity of tea also informed a number of 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 due to the trade in tea resulted in the Opium Wars. The Qing Kangxi Emperor had proclaimed that "China was the center of the world, possessing everything they could ever want or need and 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". Traders from other nation then sought to find other product, in this case opium, to sell to China to earn back the silver they were required to paid for tea and other commodities. The subsequent attempts by the Chinese Government to curtail the trade in opium led to war.[56]

Chinese small leaf type tea was introduced into India in 1836 by the British in an attempt to break the Chinese monopoly on tea.[57] In 1841, Archibald Campbell brought seeds of Chinese tea from the Kumaun region and experimented with planting tea in Darjeeling. The Alubari tea garden was opened in 1856 and Darjeeling tea began to be produced.[58] In 1848, Robert Fortune was sent by the East India Company on a mission to China to bring the tea plant back to Great Britain. He began his journey in high secrecy as his mission occurred in the lull between the Anglo-Chinese First Opium War (1839–1842) and Second Opium War (1856–1860).[59] The Chinese tea plants he brought back were introduced to the Himalayas, though most did not survive. The British had discovered that a different variety of tea was endemic to Assam and the northeast region of India and that it was used by the local Singpho people, and these were then grown instead of the Chinese tea plant and then were subsequently hybridized with Chinese small leaf type tea as well as likely closely related wild tea species. Using the Chinese planting and cultivation techniques, the British launched a tea industry by offering land in Assam to any European who agreed to cultivate it for export.[57] Tea was originally consumed only by anglicized Indians; however, it became widely popular in India in the 1950s because of a successful advertising campaign by the India Tea Board.[57]

Common processing methods of tea leaves

After basic processing, teas may be altered through additional processing steps before being sold,[91] 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. Almost all tea in bags and most loose tea sold in the West is blended. 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 new aromas and flavours to the base tea. This can be accomplished through directly adding flavouring agents, such as ginger or dried 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.[92]

Black tea is often taken with milk

The addition of milk to tea in Europe was first mentioned in 1680 by the epistolist Madame de Sévigné.[93] Many teas are traditionally drunk with milk in cultures where dairy products are consumed. These include Indian masala chai and British tea blends. These teas tend to be very hearty varieties of black tea which can be tasted through the milk, such as Assams, or the East Friesian blend. Milk is thought to neutralise remaining tannins and reduce acidity.[94][95] The Han Chinese do not usually drink milk with tea but the Manchus do, and the elite of the Qing Dynasty of the Chinese Empire continued to do so. Hong Kong-style milk tea is based on British colonial habits. Tibetans and other Himalayan peoples traditionally drink tea with milk or yak butter and salt. In Eastern European countries, Russia and Italy, tea is commonly served with lemon juice. In Poland, tea is traditionally served with a slice of lemon and is sweetened with either sugar or honey; tea with milk is called a bawarka ("Bavarian style") in Polish and is also widely popular.[96] In Australia, tea with milk is known as white tea.

The order of steps in preparing a cup of tea is a much-debated topic, and can vary widely between cultures or even individuals. Some say it is preferable to add the milk to the cup before the tea, as the high temperature of freshly brewed tea can denature the proteins found in fresh milk, similar to the change in taste of UHT milk, resulting in an inferior-tasting beverage.[97] Others insist it is better to add the milk to the cup after the tea, as black tea is often brewed as close to boiling as possible. The addition of milk chills the beverage during the crucial brewing phase, if brewing in a cup rather than using a pot, meaning the delicate flavour of a good tea cannot be fully appreciated. By adding the milk afterwards, it is easier to dissolve sugar in the tea and also to ensure the desired amount of milk is added, as the colour of the tea can be observed.[98] Historically, the order of steps was taken as an indication of class: only those wealthy enough to afford good-quality porcelain would be confident of its being able to cope with being exposed to boiling water unadulterated with milk.[99] Higher temperature difference means faster heat transfer, so the earlier milk is added, the slower the drink cools. A 2007 study published in the European Heart Journal found certain beneficial effects of tea may be lost through the addition of milk.[100]

Common varieties of black tea include Assam, Nepal, Darjeeling, Nilgiri, Rize, Keemun, and Ceylon teas. Western black teas are usually brewed for about four minutes. In many regions of the world, actively boiling water is used and the tea is often stewed. In India, black tea is often boiled for fifteen minutes or longer to make Masala chai, as a strong brew is preferred. Tea is often strained while serving.

A food safety management group of the International Organization for Standardization (ISO) has published a standard for preparing a cup of tea (ISO 3103: Tea – Preparation of liquor for use in sensory tests), primarily intended for standardizing preparation for comparison and rating purposes. It is defined as 2.0 grams of tea leaves steeped for 6 minutes per 100 ml of boiling water.

In regions of the world that prefer mild beverages, such as the Far East, green tea is steeped in water around 80 to 85 °C (176 to 185 °F). Regions such as North Africa or Central Asia prefer a bitter tea, and hotter water is used. In Morocco, green tea is steeped in boiling water for 15 minutes.

The container in which green tea is steeped is often warmed beforehand to prevent premature cooling. High-quality green and white teas can have new water added as many as five or more times, depending on variety, at increasingly higher temperatures.

Oolong tea is brewed around 82 to 96 °C (185 to 205 °F), with the brewing vessel warmed before pouring the water. Yixing purple clay teapots are the traditional brewing-vessel for oolong tea which can be brewed multiple times from the same leaves, unlike green tea, seeming to improve with reuse. In the southern Chinese and Taiwanese Gongfu tea ceremony, the first brew is discarded, as it is considered a rinse of leaves rather than a proper brew.

Pu-erh teas require boiling water for infusion. Some prefer to quickly rinse pu-erh for several seconds with boiling water to remove tea dust which accumulates from the ageing process, then infuse it at the boiling point (100 °C or 212 °F), and allow it to steep from 30 seconds to five minutes.

Meaning "spiced tea", masala chai tea is prepared using black or green tea with milk (in which case it may be called a "latte"), and may be spiced with ginger.[101]

In recent times, there has been a trend in India for Tandoor tea. This tea is prepared by placing the tea in red hot tandoor (fire oven) and then pouring the hot milky preparation when it is boiling.[102]

While most tea is prepared using hot water, it is also possible to brew a beverage from tea using room temperature or cooled water. This requires longer steeping time to extract the key components, and produces a different flavour profile. Cold brews use about 1.5 times the tea leaves that would be used for hot steeping, and are refrigerated for 4–10 hours. The process of making cold brew tea is much simpler than that for cold brew coffee.

Cold brewing has some disadvantages compared to hot steeping. If the leaves or source water contain unwanted bacteria, they may flourish, whereas using hot water has the benefit of killing most bacteria. This is less of a concern in modern times and developed regions. Cold brewing may also allow for less caffeine to be extracted.

The flavour of tea can also be altered by pouring it from different heights, resulting in varying degrees of aeration. The art of elevated pouring is used principally to enhance the flavour of the tea and improve mouthfeel, while cooling the beverage sufficiently for immediate consumption.[103]

In Southeast Asia, the practice of pouring tea from a height has been refined further using brewed black tea to which condensed milk is mixed then poured from a height alternately from matching hand-held vessels several times in quick succession. This creates a tea with entrapped air bubbles and a frothy "head", which is then immediately served in a cup. This beverage, teh tarik, literally, "pulled tea" (which has its origin as a hot Indian tea beverage), has a creamier taste than flat milk tea and is common in the region.[104]

Multiple recent reports have found that most Chinese and Indian teas contain residues of banned toxic pesticides.[124][125][126][127]

Tea production in Kenya, Malawi, Rwanda, Tanzania, and Uganda has been reported to make use of child labor according to the U.S. Department of Labor's List of Goods Produced by Child Labor or Forced Labor[128] (a report on the worst forms of child labor).

Workers who pick and pack tea on plantations in developing countries can face harsh working conditions and may earn below the living wage.[129]

A number of bodies independently certify the production of tea. Tea from certified estates can be sold with a certification label on the pack. The most important certification schemes are Rainforest Alliance, Fairtrade, UTZ Certified, and Organic, which also certify other crops such as coffee, cocoa and fruit. Rainforest Alliance certified tea is sold by Unilever brands Lipton and PG Tips in Western Europe, Australia and the US. Fairtrade certified tea is sold by a large number of suppliers around the world. UTZ Certified announced a partnership in 2008 with Sara Lee brand Pickwick tea.

Production of organic tea has risen since its introduction in 1990 at Rembeng, Kondoli Tea Estate, Assam.[130] 6,000 tons of organic tea were sold in 1999.[131] About 75% of organic tea production is sold in France, Germany, Japan, the United Kingdom, and the United States.

In 2013, China – the world's largest producer of tea – exported 325,806 tonnes, or 14% of their total crop.[132] India exported 254,841 tonnes or 20% of their total production.[132]

In 2013, the largest importer of tea was the Russian Federation with 173,070 tonnes, followed by the United Kingdom, the United States, and Pakistan.[132]

Tea bags

In 1907, American tea merchant Thomas Sullivan began distributing samples of his tea in small bags of Chinese 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 on. During World War II, tea was rationed in the United Kingdom. In 1953, after rationing in the UK ended, Tetley launched the tea bag to the UK and it was an immediate success.

The "pyramid tea bag" (or sachet), introduced by Lipton[133] and PG Tips/Scottish Blend in 1996,[134] 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. 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.[135]

A blend of loose-leaf black teas

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 sometimes vacuum-packed for freshness in aluminised packaging for storage and retail. The loose tea must be 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 (such as pu-erh) is produced for convenience in transport, storage, and ageing. It can usually be stored longer without spoilage than loose leaf tea.

Compressed tea is prepared by loosening leaves from the cake using a small knife, and steeping the extracted pieces in water. During the Tang dynasty, as described by Lu Yu, compressed tea was ground into a powder, combined with hot water, and ladled into bowls, resulting in a "frothy" mixture.[136] In the Song dynasty, the tea powder would instead be whisked with hot water in the bowl. Although no longer practiced in China today, the whisking method of preparing powdered tea was transmitted to Japan by Zen Buddhist monks, and is still used to prepare matcha in the Japanese tea ceremony.[137]

Compressed tea was the most popular form of tea in China during the Tang dynasty.[138] By the beginning of the Ming dynasty, it had been displaced by loose-leaf tea.[139] 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.[140]

"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.

Delicacy of flavour is sacrificed for convenience. 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...[141]

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).[142]

In 1983, Swiss-based Bischofszell Food Ltd., was the first company to bottle iced tea on an industrial scale.[143]