Thứ Ba, 20 tháng 3, 2012

Overview Tea


For other uses, see Tea (disambiguation).
Tea
Tea leaves steeping in a zhong čaj 05.jpg
Green tea being infused in a gaiwan
TypeHot or cold beverage
Country of originChina
IntroducedApprox. 10th century BC[1]
Tea plant (Camellia sinensis) from Köhler's Medicinal Plants
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself.
After water, tea is the most widely consumed beverage in the world.[2] It has a cooling, slightly bitter, astringent flavour which many people enjoy.[3]
Consumption of tea (especially green) is beneficial to health and longevity given its significantantioxidant, flavanols, flavonoids, and polyphenols content.[4][5] Consumption of green tea is associated with a lower risk of diseases that cause functional disability, such as “stroke, cognitive impairment, and osteoporosis” in the elderly.[6][7]
Tea consumption is strongly associated with a calm but alert and focused, relatively productive (alpha wave dominant), mental state in humans. This mental state is also common to meditativepractice.[8]
The phrase herbal tea usually refers to infusions of fruit or herbs made without the tea plant, such as rosehip tea or chamomile tea. Alternative phrases for this are tisane or herbal infusion, both bearing an implied contrast with "tea" as it is construed here.

Contents

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[edit]Cultivation and harvesting

Tea plantation in the Cameron Highlands in Malaysia
Camellia sinensis is an evergreen plant that grows mainly in tropical and sub-tropical climates.[9]Some varieties can also tolerate marine climates and are cultivated as far north as Pembrokeshirein the British mainland[10] and Washington in the United States.[11]
Leaves of Camellia sinensis, the tea plant.
Tea plants are propagated from seed or by cutting; it takes approximately 4 to 12 years for a tea plant to bear seed, and about 3 years before a new plant is ready for harvesting.[9] In addition to azone 8 climate or warmer, tea plants require at least 127 cm. (50 inches) of rainfall a year and prefer acidic soils.[12] Traditional Chinese Tea Cultivation and Studies believes that high-quality tea plants are cultivated at elevations of up to 1,500 metres (4,900 ft): at these heights, the plants grow more slowly and acquire a better flavour.[13]
Only the top 1-2 inches of the mature plant are picked. These buds and leaves are calledflushes.[14] A plant will grow a new flush every seven to fifteen days during the growing season, and leaves that are slow in development always produce better flavored teas.[9]
A tea plant will grow into a tree of up to 16 metres (52 ft) if left undisturbed,[9] but cultivated plants are pruned to waist height for ease of plucking.[15]
Two principal varieties are used: the China plant (C. sinensis sinensis), used for most Chinese, Formosan and Japanese teas (but not Pu-erh); and the clonal Assam tea plant (C. sinensis assamica), used in most Indian and other teas (but not Darjeeling). Within these botanical varieties, there are many strains and modern Indian clonal varieties. Leaf size is the chief criterion for the classification of tea plants,[16] with three primary classifications being: Assam type, characterized by the largest leaves; China type, characterized by the smallest leaves; and Cambod, characterized by leaves of intermediate size.[16][17]

[edit]Processing and classification

Main article: Tea processing
Tea leaf processing methods
Fresh tea leaves of different sizes. The smaller the leaf, the more expensive the tea.
Teas can generally be divided into categories based on how they are processed. There are at least six different types of tea: white, yellow, green, oolong, black, and post-fermented teas[18] of which the most commonly found on the market are white, green, oolong, and black. Some varieties, such as traditional oolong tea[19] and Pu-erh tea, a post-fermented tea, can be used medicinally.[20]
After picking, the leaves of Camellia sinensis soon begin to wilt and oxidize, unless they are immediately dried. The leaves turn progressively darker as their chlorophyll breaks down andtannins are released. This enzymatic oxidation process, known as fermentation in the tea industry, is caused by the plant's intracellular enzymes and causes the tea to darken. In tea processing, the darkening is stopped at a predetermined stage by heating, which deactivates the enzymesresponsible. In the production of black teas, the halting of oxidization by heating is carried out simultaneously with drying.
Tea harvest on the eastern shores of theBlack Sea, ca. 1905–15.
Without careful moisture and temperature control during manufacture and packaging, the tea may become unfit for consumption, due to the growth of undesired molds and bacteria. At minimum it may alter the taste and make it undesirable.
Tea is traditionally classified based on the techniques with which it is produced and processed.[21]

[edit]Blending and additives

Main article: Tea blending and additives
Although single estate teas are available, almost all teas in bags and most other teas sold in the West are blends. Blending may occur in the tea-planting area (as in the case of Assam), or teas from many areas may be blended. The aim of blending is to obtain better taste, higher price, or both, as a more expensive, better-tasting tea may cover the inferior taste of cheaper varieties.
Some teas are not pure varieties, but have been enhanced through additives or special processing. Tea is highly receptive to inclusion of various aromas; this may cause problems in processing, transportation, and storage, but also allows for the design of an almost endless range of scented and flavored variants, such as bergamot (Earl Grey), vanilla, caramel, and many others.

[edit]Content

Tea contains catechins, a type of antioxidant. In a freshly picked tea leaf, catechins can compose up to 30% of the dry weight. Catechins are highest in concentration in white and green teas, while black tea has substantially fewer due to its oxidative preparation.[22][23] Research by the U.S. Department of Agriculture has suggested that levels of antioxidants in green and black tea do not differ greatly, as green tea has anoxygen radical absorbance capacity (ORAC) of 1253 and black tea an ORAC of 1128 (measured in μmolTE/100g).[24] Antioxidant content, measured by the lag time for oxidation of cholesterol, is improved by the cold water steeping of varieties of tea.[25] Tea also contains theanineand the stimulant caffeine at about 3% of its dry weight, translating to between 30 mg and 90 mg per 8 oz (250 ml) cup depending on type, brand[26] and brewing method.[27] Tea also contains small amounts of theobromine and theophylline.[28] Due to modern day environmental pollution fluoride and aluminum have also been found to occur in tea, with certain types of brick tea made from old leaves and stems having the highest levels. This occurs due to the tea plant's high sensitivity to and absorption of environmental pollutants.[29][30]
Although tea contains various types of polyphenols and tannin, tea does not contain tannic acid.[31] Tannic acid is not an appropriate standard for any type of tannin analysis because of its poorly defined composition.[32]

[edit]Origin and history

Main article: History of tea
Tea weighing station north of Batumi,Russian Empire before 1915
Tea plants are native to East and South Asia and probably originated around the point of confluence of the lands of northeast India, north Burma and southwest China.
Although there are tales of tea's first use as a beverage, no one is sure of its exact origins. The first recorded drinking of tea is in China, with the earliest records of tea consumption dating back to the 10th century BC.[1][33] It was already a common drink during the Qin Dynasty (3rd century BC) and became widely popular during the Tang Dynasty, when it was spread to Korea and Japan. Trade of tea by the Chinese to Western nations in the 19th century spread tea and the tea plant to numerous locations around the world.
Tea was imported to Europe during the Portuguese expansion of the 16th century, at which time it was termed chá. In 1750, tea experts traveled from China to the Azores Islands, and planted tea, along with jasmines and mallows, to give the tea aroma and distinction. Both green tea and black tea continue to grow in the islands, which are the main suppliers to continental Portugal. Catherine of Braganza, wife of Charles II, took the tea habit to Great Britain around 1660, but it was not until the 19th century Britain that tea became as widely consumed as it is today. In Ireland, tea had become an everyday beverage for all levels of society by the late 19th century, but it was first consumed as a luxury item on special occasion such as religious festivals, wakes, and domestic work gatherings such as quiltings.[34]

[edit]Health effects

Main article: Health effects of tea
Several of the potential health benefits proposed for tea are outlined in this excerpt from Mondal (2007, pp. 519–520) as following:
Tea leaves contain more than 700 chemicals, among which the compounds closely related to human health are flavanoids,amino acids, vitamins (C, E and K), caffeine and polysaccharides. Moreover, tea drinking has recently proven to be associated with cell-mediated immune function of the human body. Tea plays an important role in improving beneficial intestinal microflora, as well as providing immunity against intestinal disorders and in protecting cell membranes from oxidative damage. Tea also prevents dental caries due to the presence of fluorine. The role of tea is well established in normalizing blood pressure, lipid depressing activity, prevention of coronary heart diseases and diabetes by reducing the blood-glucose activity. Tea also possesses germicidal and germistatic activities against various gram-positive and gram negative human pathogenic bacteria. Both green and black tea infusions contain a number of antioxidants, mainly catechins that have anti-carcinogenic, anti-mutagenic and anti-tumoric properties.
Catechins in green tea possess anticancer properties against "cancer in various organs, including the colorectum and liver, and are known to exert anti-obesity, antidiabetic, and anti-inflammatory effects." "Branched-chain amino acids in green tea may prevent progressive hepatic failure in patients with chronic liver diseases, and might be effective for the suppression of obesity-related liver carcinogenesis."[5]
Anticarcinogenic effects of tea polyphonols has been provided by numerous in vitro and experimental studies, which describe their action to “bind directly to carcinogens, induce Phase II enzymes such as UDP-glucuronosyl transferase and inhibit heterocyclic amine formation.” “Molecular mechanisms, including catechin-mediated induction of apoptosis and cell cycle arrest, inhibition of transcription factors NF-κB and AP-1 and reduction of protein tyrosine kinase activity and c-jun mRNA expression have also been suggested as relevant chemopreventive pathways for tea.” Protective effects from tea consumption are observed less frequently in populations where intake of black tea predominates. [35]
Numerous recent epidemiological studies have been conducted to investigate the effects of green tea consumption on the incidence of human cancers. These studies suggest significant protective effects of green tea against oral, pharyngeal, esophageal, prostate, digestive, urinary tract, pancreatic, bladder, skin, lung, colon, breast, and liver cancers, and lower risk for cancer metastasis and recurrence.[35]
Possibly most noteworthy are human intervention studies that find consumption of green tea cuts the risk of getting ovarian and endometrial cancers, and advanced prostate cancer by 50%.[36][37][38]
Cholesterol and blood sugar levels are lowered significantly by drinking green tea.[39] Drinking green tea is negatively associated with diabetes, possibly due to moderated oxidative stress on fats, which may reduce insulin resistance [40]
Consumption of green tea consumption is associated with a lower risk of diseases that cause functional disability, such as “stroke, cognitive impairment, and osteoporosis” in the elderly.[6] Specific to mental function, researchers in 2010 found that people who consumed tea had significantly less cognitive decline than non-tea drinkers. The study used data on more than 4,800 men and women aged 65 and older to examine change in cognitive function over time. Study participants were followed for up to 14 years for naturally-occurring cognitive decline. (AAICAD 2010; Lenore Arab, PhD; UCLA[7]
L-theanine in tea may reduce stress by inducing a calm but alert, focused, and relatively productive (alpha wave dominant) mental state in humans. This mental state is also common to meditative practice.[8]

[edit]The word tea

The Chinese character for tea is 茶. It is pronounced differently in the various Chinese languages. Most pronounce it along the lines of cha(Mandarin has chá), but the Min varieties along the central coast of China and in Southeast Asia pronounce it like te. These two pronunciations of the Chinese word for tea have made their separate ways into other languages around the world:[41]
  • Te: From tê in Amoy dialect, spoken in Fujian Province and Taiwan. It reached the West from the port of Xiamen (Amoy), once a major point of contact with Western European traders such as the Dutch, who spread it to Western Europe.
  • Cha: From the Cantonese chàh, spoken in Guangzhou (Canton) and the ports of Hong Kong and Macau, also major points of contact, especially with the Portuguese, who spread it to India in the 16th century. The Korean and Japanese words cha come from the Mandarinchá.
The widespread form chai comes from Persian چای chay. This derives from Mandarin chá,[42] which passed overland to Central Asia and Persia, where it picked up the Persian grammatical suffix -yi before passing on to Russian, Arabic, Urdu, Turkish, etc.[43]
English has all three forms: cha or char (both /ˈtʃɑː/), attested from the 16th century; tea, from the 17th; and chai, from the 20th.
Languages in more intense contact with Chinese, Sinospheric languages like Vietnamese, Zhuang, Tibetan, Korean, and Japanese, may have borrowed their words for tea at an earlier time and from a different variety of Chinese, so-called Sino-Xenic pronunciations. Korean and Japanese, for example, retain early pronunciations of ta and da. Ta comes from the Tang Dynasty court at Chang'an: that is, from Middle Chinese. Japanese da comes from the earlier Southern Dynasties court at Nanjing, a place where the consonant was still voiced, as it is today in neighboring Shanghainese zo. Vietnamese and Zhuang have southern cha-type pronunciations.

[edit]Derivatives of te

LanguageNameLanguageNameLanguageNameLanguageNameLanguageName
AfrikaansteeArmenian (Western Dialect)թեյ teyEuskarateaCatalanteCzechté or thé (1)
DanishteDutchtheeEnglishteaEsperantoteoEstoniantee
FaroeseteFinnishteeFrenchthéWest FrisianteeGalicianté
GermanTeeGreekτέϊον téïonHebrewתה, teHungarianteaIcelandicte
IndonesiantehIrishtaeItaliantè or theJavanesetèhKhmerតែ tae
scientificLatintheaLatviantējaLeonesetéLimburgishtièLow SaxonTee [tʰɛˑɪ]or Tei [tʰaˑɪ]
MalaytehMalayalamതേയിലtheyilaMongolianцай tsaiNorwegianteOccitantè
Polishherbata(2)Scots Gaelictì, teathaSinhaleseté තේSpanishtéScotstea [tiː] ~ [teː]
SundaneseentèhSwedishteTamilதேநீர்theneer (3)TeluguతేనీరుtheneeruWelshte
Notes:
  • (1) té or thé, but this term is considered archaic and is a literary expression; since roughly second half of 20th century, čaj is used for "tea" in Czech language, see the following table
  • (2) from Latin herba thea
  • (3) neer means water; theyilai means "tea leaf" (ilai = leaf)

[edit]Derivatives of ta

LanguageNameLanguageName
Japaneseだ da, た ta (1)Korean다 da [ta] (1)
  • (1) cha is an alternative pronunciation of "tea" in Japanese and Korean; see below

[edit]Derivatives of cha

LanguageNameLanguageNameLanguageNameLanguageNameLanguageName
Assameseচাহ sahBanglaচা chaCapampanganchaCebuanotsaEnglishcha or char
Gujaratiચા chāJapaneseチャ cha, さ sa (1)Kannadaಚಹಾ chahāKhasishaKonkaniचा chā
Korean차 cha (1)KurdishçaLaoຊາ saaMalayalamchāyāMarathiचहा chahā
Oriyaଚା chaPersianچا chaPunjabiچا ਚਾਹ chāhPortuguesecháSindhichahen چانهه
SomalishaahSylhetisaahTagalogtsaaThaiชา chaTibetanཇ་ ja
Vietnamesetrà and chè(2)
Notes:
  • (1) The main pronunciations of 茶 in Korea and Japan are 차 cha and ちゃ cha, respectively. (Japanese ocha (おちゃ) is honorific.) These are connected with the pronunciations at the capitals of the Song and Ming dynasties.
  • (2) Trà and chè are variant pronunciations of 茶; the latter is used mainly in northern Vietnam and describes a tea made with freshly picked leaves.

[edit]Derivatives of chay

LanguageNameLanguageNameLanguageNameLanguageNameLanguageName
AlbaniançajAmharicሻይ shaiArabicشاي shāyArmenian (Eastern Dialect)չայ chāiAramaicܟ݈ܐܝ chai
AzerbaijaniçayBosniančajBulgarianчай chaiCroatiančajCzechčaj (2)
EnglishchaiFinnish dialectaltsai, tsaiju,saiju orsaikkaGeorgianჩაი chaiGreekτσάι tsáiHindiचाय chai
Kazakhшай shaiKyrgyzчай chaiKinyarwandaicyayiMacedonianчајMalayalamചായchaaya
Mongolianцай tsaiNepalichiyā चियाPashtoچای chaiPersianچای chay (1)Romanianceai
Russianчай chaiSerbianчај čajSlovakčajSlovenečajSwahilichai
Tajikчой choyTlingitcháayuTeluguఛాయchaayaTurkishçayTurkmençay
Ukrainianчай chaiUrduچائے chaiUzbekchoy
Notes:
  • (1) Derived from the earlier pronunciation چا cha.

[edit]Etymological observations

The different words for tea fall into two main groups: "te-derived" (Hokkien) and "cha-derived" (Cantonese and Mandarin)[43] reveal where nations acquired their tea and tea culture.
  • The Portuguese, the first Europeans to import the herb in large amounts, took the Cantonese form cha ca. the year 1550 from their trading posts in the south of China, especially Macau.
  • India most likely got their tea cultures from Cantonese or Portuguese traders.
  • In Central Asia, Mandarin cha developed into Persian chay, and this form spread with Persian trade and cultural influence.
  • Russia encountered tea in Central Asia.
  • Europeans such as the Dutch who took the Min form teh may have acquired it through trade directly from Hokkien (Fujian), or from Hokkienese or Malay traders in Java.
There are counter-examples: the first tea to reach Britain was traded by the Dutch from Hokkien, which uses te, and although later most British trade went through Canton, which uses cha, the Hokkien pronunciation continued to be the more popular.
At times, a te form will follow a cha form, or vice versa, giving rise to both in one language, at times one an imported variant of the other.
  • In North America, the word chai is used to refer almost exclusively to the Indian masala chai (spiced tea) beverage, in contrast to teaitself.
  • The inverse pattern is seen in Moroccan colloquial Arabic (Darija), "ash-shay" means "generic, or black Middle Eastern tea" whereas "at-tay" refers particularly to Zhejiang or Fujian green tea with fresh mint leaves. The Moroccans are said to have acquired this taste for green tea— unique in the Arab world— for East Chinese green tea after the ruler Mulay Hassan exchanged some European hostages captured by the Barbary Pirates for a whole ship of Chinese tea. See Moroccan tea culture.
  • The colloquial Greek word for tea is tsáï, from Slavic chai. Its formal equivalent, used in earlier centuries, is téïon, from tê.
  • The Polish word for a tea-kettle is czajnik, which could be derived directly from chai or from the cognate Russian word. However, tea in Polish is herbata, which, as well as Lithuanian arbata, was derived from the Latin herba thea, meaning "tea herb."
  • The normal word for tea in Finnish is tee, which is a Swedish loan. However, it is often colloquially referred, especially in Eastern Finland and in Helsinki as tsai, tsaiju, saiju or saikka, which is cognate to Russian word chai. The latter word refers always to black tea, while green tea is always tee.
  • In Ireland, or at least in Dublin, the term cha is sometimes used for "tea," as is pre-vowel-shift pronunciation "tay" (from which the Irish Gaelic word "tae" is derived[citation needed]). Char was a common slang term for tea throughout British Empire and Commonwealth military forces in the 19th and 20th centuries, crossing over into civilian usage.
  • The British English slang word "char" for "tea" arose from its Cantonese Chinese pronunciation "cha" with its spelling affected by the fact that ar is a more common way of representing the phoneme /ɑː/ in British English.`

[edit]Tea culture

Main article: Tea culture
Pakistani noon chai with its distinctive pink color
Masala chai from the Indian subcontinent
Tea may be consumed early in the day to heighten alertness; it contains theophylline and boundcaffeine[3] (sometimes called theine). Decaffeinated brands are also sold.
While tea is the second most consumed beverage on Earth after water, in many cultures it is also had at elevated social events, such as afternoon tea and the tea party. Tea ceremonies have arisen in different cultures, such as the Chinese and Japanese tea ceremonies, each of which employs traditional techniques and ritualized protocol of brewing and serving tea for enjoyment in a refined setting. One form of Chinese tea ceremony is the Gongfu tea ceremony, which typically uses small Yixing clay teapots and oolong tea.
Tea is prevalent in most cultures in the Middle East. In Arab culture, tea is a focal point for social gatherings. In Iranian (Persian) and Pakistani cultures, tea is so widely consumed that it is generally the first thing offered to a household guest.[44]
In Pakistan, both black and green teas are popular and are known locally as sabz chai andkahwah, respectively. The popular green tea called kahwah is often served after every meal inKhyber Pakhtunkhwa, which is where the Khyber Pass of the Silk Road is found, and in thePashtun belt of Balochistan. In the Kashmir region of Pakistan, Kashmiri chai or noon chai, a pink, milky tea with pistachios and cardamom, is consumed primarily at special occasions, weddings, and during the winter months when it is sold in many kiosks. In the northern Pakistan regions ofChitral and Gilgit-Baltistan, a salty, buttered Tibetan-style tea is consumed.
In the United States and Canada, 80% of tea is consumed cold, as iced tea.[45] Sweet tea is a cultural symbol of the southern US, and is common in that portion of the country.
In India, tea is one of the most popular hot beverages. It is consumed daily in almost all homes, offered to guests, consumed in high amounts in domestic and official surroundings and is made with the addition of a lot of milk with or without spices. It is also served with biscuits which are dipped in the tea and eaten before consuming the tea. More often than not, it is drunk in "doses" of small cups rather than one large cup.
In the United Kingdom, especially England, tea is known as the 'national drink'. It is consumed daily and often by a majority of people across the country, and is perceived as one of Britain's cultural beverages. In British homes, it is customary good manners for a host to offer tea to guests soon after their arrival. The British prefer black tea, served in mugs with milk and perhaps sugar. Tea bags are almost always used;PG Tips is the most popular brand.[citation needed] Tea is generally consumed at home; outside the home in cafés, coffee is the drink of choice for many people. Afternoon tea with cakes on fine porcelain is a cultural stereotype, sometimes available in quaint tea-houses. In the north of England 'tea' also refers to the evening meal, or 'dinner' as it is known in standard English.
In Burma, tea is consumed not only as hot drinks, sweet tea and green tea known locally as laphet-yay and laphet-yay-gyan respectively. But also pickled tea leaves, known locally as laphet, are also a national delicacy. Pickled tea is usually eaten with roasted sesame seeds, crispy fried beans, roasted peanuts and fried garlic chips.

[edit]Preparation

Further information: Tea culture
Tea kettle over hot coal at a tea house in Jiufeng, Taiwan
The traditional method of making a cup of tea is to place loose tea leaves, either directly or in a tea infuser, into a tea pot or teacup and pour hot water over the leaves. After a couple of minutes the leaves are usually removed again, either by removing the infuser, or by straining the tea while serving.
Most green teas should be allowed to steep for about two or three minutes, although some types of tea require as much as ten minutes, and others as little as thirty seconds. The strength of the tea should be varied by changing the amount of tea leaves used, not by changing the steepingtime. The amount of tea to be used per amount of water differs from tea to tea but one basic recipe may be one slightly heaped teaspoon of tea (about 5 ml) for each teacup of water (200–240 ml) (7–8 oz) prepared as above. Stronger teas, such as Assam, to be drunk with milk are often prepared with more leaves, and more delicate high grown teas such as a Darjeeling are prepared with somewhat fewer (as the stronger mid-flavors can overwhelm the champagne notes).
The best temperature for brewing tea depends on its type. Teas that have little or no oxidation period, such as a green or white tea, are best brewed at lower temperatures, between 65 and 85 °C (149 and 185 °F), while teas with longer oxidation periods should be brewed at higher temperatures around 100 °C (212 °F). The higher temperatures are required to extract the large, complex, flavorful phenolic molecules found in fermented tea. In addition, boiling reduces the dissolved oxygen content of water. Dissolved oxygen would otherwise react with phenolic molecules (anti-oxidants) to turn them brown and reduce their potency as anti-oxidants. To preserve the anti-oxidant potency, especially for green and white teas brewed at a lower temperature, water should be boiled vigorously to boil off any dissolved oxygen and then allowed to cool to the appropriate temperature before adding to the tea. An additional health benefit of boiling water before brewing tea is the sterilizationof the water and reduction of any dissolved Volatile Organic Compounds (VoC's), chemicals which are often harmful.[46][47]
TypeWater Temp.Steep TimeInfusions
White Tea65 to 70 °C (149 to 158 °F)1–2 minutes3
Yellow Tea70 to 75 °C (158 to 167 °F)1–2 minutes3
Green Tea75 to 80 °C (167 to 176 °F)1–2 minutes4-6
Oolong Tea80 to 85 °C (176 to 185 °F)2–3 minutes4-6
Black Tea99 °C (210 °F)2–3 minutes2-3
Pu'er Tea95 to 100 °C (203 to 212 °F)LimitlessSeveral
Herbal Tea99 °C (210 °F)3–6 minutesVaried
Some tea sorts are often brewed several times using the same tea leaves. Historically, in China, tea is divided into a number of infusions. The first infusion is immediately poured out to wash the tea, and then the second and further infusions are drunk. The third through fifth are nearly always considered the best infusions of tea, although different teas open up differently and may require more infusions of hot water to produce the best flavor.[48]
One way to taste a tea, throughout its entire process, is to add hot water to a cup containing the leaves and after about 30 seconds to taste the tea. As the tea leaves unfold (known as "The Agony of the Leaves") they give up various parts of themselves to the water and thus the taste evolves. Continuing this from the very first flavours to the time beyond which the tea is quite stewed will allow an appreciation of the tea throughout its entire length.[49]
Black tea infusion

[edit]Black tea

In the West, water for black tea is usually added near the boiling point of water, at around 99 °C(210 °F). Many of the active substances in black tea do not develop at temperatures lower than90 °C (194 °F).[citation needed] Lower temperatures are used for some more delicate teas. The temperature will have as large an effect on the final flavor as the type of tea used. The most common fault when making black tea is to use water at too low a temperature. Since boiling point drops with increasing altitude, it is difficult to brew black tea properly in mountainous areas. It is also recommended that the teapot be warmed before preparing tea, easily done by adding a small amount of boiling water to the pot, swirling briefly, before discarding. In the West, black teas are usually brewed for about 4 minutes and are usually not allowed to steep for less than 30 seconds or more than about five minutes (a process known as brewing or mashing in Britain). In many regions of the world, however, boiling water is used and the tea is often stewed. For example, in India black tea is often boiled for fifteen minutes or longer as a strong brew is preferred for making Masala chai. When the tea has brewed long enough to suit the tastes of the drinker, it should be strained while serving. The popular varieties of black (red) tea include Assam tea, Nepal tea, Darjeeling tea, Nilgiri tea,Turkish tea and Ceylon tea.

[edit]Green tea

Water for green tea, according to regions of the world that prefer mild tea, should be around 80 to 85 °C (176 to 185 °F); the higher the quality of the leaves, the lower the temperature. Hotter water will produce a bitter taste. However, this is the method used in many regions of the world, such as North Africa or Central Asia where bitter tea is appreciated. For example, in Morocco green tea is steeped in boiling water for fifteen minutes. In the West and Far East a milder tea is appreciated. The container in which the tea is steeped, the mug, or teapot is often warmed beforehand so that the tea does not immediately cool down. High-quality green and white teas can have new water added as many as five or more times, depending on variety, at increasingly high temperatures.

[edit]Oolong tea

Oolong teas should be brewed around 90 to 100 °C (194 to 212 °F), and again the brewing vessel should be warmed before pouring in the water. Yixing purple clay teapots are the traditional brewing-vessel for oolong tea. For best results use spring water, as the minerals in spring water tend to bring out more flavor in the tea. High quality oolong can be brewed multiple times from the same leaves, and unlike green tea it improves with reuse. It is common to brew the same leaves three to five times, the third steeping usually being the best.

[edit]Premium or delicate tea

A strainer is often used when tea is made with tea-leaves in a teapot,
Some teas, especially green teas and delicate oolong teas, are steeped for shorter periods, sometimes less than 30 seconds. Using a tea strainer separates the leaves from the water at the end of the brewing time if a tea bag is not being used. However, the black Darjeeling tea, a premium Indian tea, needs a longer than average steeping time. Elevation and time of harvest offer varying taste profiles; proper storage and water quality also have a large impact on taste.

[edit]Pu-erh tea

Pu-erh tea is also called Pu'er tea. 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 aging process, then infuse it at the boiling point (100°C or 212°F), and allow it to steep from 30 seconds to five minutes.

[edit]Serving

In order to preserve the pre-tannin tea without requiring it all to be poured into cups, a second teapot may be used. The steeping pot is best unglazed earthenware; Yixing pots are the best known of these, famed for the high quality clay from which they are made. The serving pot is generally porcelain, which retains the heat better. Larger teapots are a post-19th century invention, as tea before this time was very rare and very expensive. Experienced tea-drinkers often insist that the tea should not be stirred around while it is steeping (sometimes called windingin the UK). This, they say, will do little to strengthen the tea, but is likely to bring the tannins out in the same way that brewing too long will do. For the same reason one should not squeeze the last drops out of a teabag; if stronger tea is desired, more tea leaves should be used.

[edit]Additives

Further information: Tea blending and additives
Tea is sometimes taken with milk
The addition of milk to tea in Europe was first mentioned in 1680 by the epistolist Madame de Sévigné.[50] 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 neutralize remaining tannins and reduce acidity.[51][52] The Han Chinese do not usually drink milk with tea (or indeed use milk at all) 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, Poland and Hungary) and Italy people commonly have their tea with lemon juice. In Poland, tea with milk is called a bawarka("Bavarian style"), and is often drunk by pregnant and nursing women.
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 that it is preferable to add the milk 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.[53] Others insist that it is better to add the milk after brewing the tea, as most teas need to be 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 that the delicate flavor 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 that the desired amount of milk is added, as the color of the tea can be observed.[citation needed]
Moroccan tea being served. It is poured from a distance to produce a foam on the tea.
A 2007 study published in the European Heart Journal found that certain beneficial effects of tea may be lost through the addition of milk.[54]
Many flavourings are added to varieties of tea during processing. Among the best known are ChineseJasmine tea, with jasmine oil or flowers, the spices in Indian Masala chai, and Earl Grey tea, which contains oil of bergamot. A great range of modern flavours have been added to these traditional ones. In eastern India people also drink lemon tea or lemon masala tea. Lemon tea simply contains hot tea with lemon juice and sugar. Masala lemon tea contains hot tea with roasted cumin seed powder, lemon juice, black salt and sugar which gives it a tangy, spicy taste.
Other popular additives to tea by the tea-brewer or drinker include sugar, liquid honey or a solid Honey Drop, agave nectar, fruit jams, and mint. In China sweetening tea was traditionally regarded as a feminine practice. In colder regions such as Mongolia, Tibet and Nepal, butter is added to provide necessary calories. Tibetan butter tea contains rock salt and dre (yak) butter, which is then churned vigorously in a cylindrical vessel closely resembling a butter churn. The same may be said for salt tea, which is consumed in some cultures in the Hindu Kush region of northern Pakistan.
Alcohol, such as whisky or brandy, may also be added to tea.
The flavor of the tea can also be altered by pouring it from different heights, resulting in varying degrees ofoxidization. The art of high-altitude pouring is used principally by people in Northern Africa (e.g. Morocco,Algeria, Mauritania and Libya), but also in West Africa (e.g. Guinea, Mali, Senegal) and can positively alter the flavor of the tea, but it is more likely a technique to cool the beverage destined to be consumed immediately. In certain cultures the tea is given different names depending on the height it is poured from. In Mali, gunpowder tea is served in series of three, starting with the highest oxidization or strongest, unsweetened tea (cooked from fresh leaves), locally referred to as "bitter as 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.
In Southeast Asia, particularly in Malaysia, the practice of pouring tea from a height has been refined further using black tea to which condensed milk is added, poured from a height from one cup to another several times in alternating fashion and in quick succession, to create a tea with entrapped air bubbles creating a frothy "head" in the cup. This beverage, teh tarik, literally, "pulled tea," has a creamier taste than flat milk tea and is extremely popular in the region. Tea pouring in Malaysia has been further developed into an art form in which a dance is done by people pouring tea from one container to another, which in any case takes skill and precision. The participants, each holding two containers, one full of tea, pour it from one to another. They stand in lines and squares and pour the tea into each others' pots. The dance must be choreographed to allow anyone who has both pots full to empty them and refill those of whoever has no tea at any one point.

[edit]Economics

Tea factory in Taiwan
See also: List of countries by tea consumption per capita
Tea is the most popular manufactured drink in the world in terms of consumption. Its consumption equals all other manufactured drinks in the world – including coffee, chocolate, soft drinks, and alcohol – put together.[2] 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 there 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[55] although the per capita consumption of tea remains a modest 750 grams per person every year. Turkey, with 2.5 kg of tea consumed per person per year, is the world's greatest per capita consumer.[56]

[edit]Production

In 2003, world tea production was 3.21 million tonnes annually.[57] In 2008, world tea production reached over 4.73 million tonnes.[57] The largest producers of tea are the People's Republic of China, India, Kenya, Sri Lanka, and Turkey.
Percentage of total tea production in 2008
   Less than 0.5% or non-significant quantities
   From 0.5 to 1%.
   From 1 to 5%.
   From 5 to 10%.
   From 10 to 20%.
   More than 20%
Percentage of total global tea production by country in 2007
The following table shows the amount of tea production (in tonnes) by leading countries in recent years. Data is generated by the Food and Agriculture Organization (FAO) of the United Nations as of January 2010.[57]
Country200620072008
 China1,047,3451,183,0021,275,384
 India928,000949,220805,180
 Kenya310,580369,600345,800
 Sri Lanka310,800305,220318,470
 Turkey201,866206,160198,046
 Vietnam151,000164,000174,900
 Indonesia146,858150,224150,851
 Japan91,80094,10094,100
 Argentina72,12976,00076,000
 Iran59,18060,00060,000
 Bangladesh58,00058,50059,000
 Malawi45,00946,00046,000
 Uganda34,33444,92342,808
Other countries189,551193,782205,211
Total3,646,4523,887,3083,833,750

[edit]Certification

Workers who pick and pack tea on plantations in developing countries can face harsh working conditions and can earn below the living wage.[58]
There are a number of bodies that 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. All these schemes certify other crops (like coffee, cocoa and fruit) as well. 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 announce a partnership in 2008 with Sara Lee brand Pickwick tea.
Production of organic tea is rising; 3,500 tonnes of organic tea were grown in 2003. The majority of this tea (about 75%) is sold in France,Germany, Japan, the United Kingdom and the United States.

[edit]Trade

[icon]This section requires expansion.
According to the FAO, in 2007 the largest importer of tea, by weight, was the Russian Federation, followed by the United Kingdom, Pakistan, and the United States.[59] Kenya, China, India and Sri Lanka were the largest exporters of tea in 2007 (with exports of: 374229, 292199, 193459 and 190203 tonnes respectively).[59][60] The largest exporter of black tea in the world is Kenya, while the largest producer (and consumer) of black tea in the world is India.[60][61]

[edit]Packaging

[edit]Tea bags

Tea bags
Main article: Tea bag
In 1907, American tea merchant Thomas Sullivan began distributing samples of his tea in small bags of Chinese silk with a drawstring. Consumers noticed that they could simply leave the tea in the bag and re-use it with fresh tea. However, the potential of this distribution/packaging method would not be fully realized until later on. During World War II, tea was rationed.[where?] In 1953 (after rationing in the UK ended), Tetley launched the tea bag to the UK and it was an immediate success.
Tea leaves are packed into a small envelope (usually composed of paper) known as a tea bag. The use of tea bags is easy and convenient, making tea bags popular for many people today. However, the use of tea bags has negative aspects as well. The tea used in tea bags is commonly fanningsor "dust", the waste product produced from the sorting of higher quality loose leaf tea. However, this is not true for all brands of tea; many high quality specialty teas are available in bag form.[citation needed] It is commonly held among tea aficionados that this method provides an inferior taste and experience. The paper used for the bag can also be tasted by many, which can detract from the tea's flavor. Because fannings and dust are a lower quality of the tea to begin with, the tea found in tea bags is less finicky when it comes to brewing time and temperature.
Additional reasons why bag tea is considered less well-flavored include:
  • Dried tea loses its flavor quickly on exposure to air. Most bag teas (although not all) contain leaves broken into small pieces; the greatsurface area to volume ratio of the leaves in tea bags exposes them to more air, and therefore causes them to go stale faster. Loose tea leaves are likely to be in larger pieces, or to be entirely intact.[citation needed]
  • Breaking up the leaves for bags extracts flavored oils.[citation needed]
  • The small size of the bag does not allow leaves to diffuse and steep properly.[citation needed]
  • Some tea bags are made using a wet paper strength-reinforcing coating using epichlorohydrin, a known carcinogen.[62][63]
The "pyramid tea bag" (or sachet) introduced by Lipton[64] and PG Tips/Scottish Blend in 1996,[65] 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]. However, some types of pyramid tea bags have been criticized as being environmentally unfriendly, since their synthetic material does not break down in landfills as loose tea leaves and paper tea bags do.[66]

[edit]Loose tea

Loose-leaf tea
The tea leaves are packaged loosely in a canister or other container. Rolled gunpowder tea leaves, which resist crumbling, are commonly vacuum packed for freshness in aluminized packaging for storage and retail. The portions must be individually measured by the consumer for use in a cup, mug, or teapot. This allows greater flexibility, letting the consumer brew weaker or stronger tea as desired, but convenience is sacrificed. Strainers, "tea presses," filtered teapots, and infusion bags are available commercially to avoid having to drink the floating loose leaves and to prevent over-brewing. A more traditional, yet perhaps more efficient way around this problem is to use a three-piece lidded teacup, called a gaiwan. The lid of the gaiwan can be tilted to decant the leaves while pouring the tea into a different cup for consumption.

[edit]Compressed tea

Some teas (particularly Pu-erh tea) are still compressed for transport, storage, and aging convenience. The tea brick remains in use in the Himalayan countries or Mongolian steppes. The tea is prepared and steeped by first loosening leaves off the compressed cake using a small knife. Compressed teas can usually be stored for longer periods of time without spoilage when compared with loose leaf tea.

[edit]Instant tea

In recent times, "instant teas" are becoming popular, similar to freeze dried instant coffee. Similar products also exist for instant iced tea, due to the convenience of not requiring boiling water. Instant tea was developed in the 1930s, but not commercialized until later. Nestea introduced the first instant tea in 1946, while Redi-Tea introduced the first instant iced tea in 1953.
These products often come with added flavors, such as Chai, vanilla, honey or fruit, and may also contain powdered milk. Tea connoisseurstend to criticize these products for sacrificing the delicacies of tea flavour in exchange for convenience.

[edit]Canned tea

Main article: Canned tea
Canned tea is a form of tea that has already been prepared, and is sold ready to drink. Canned tea was first launched in 1981 in Japan. As such, it is a fairly recent innovation.

[edit]Storage

Tea has a shelf life that varies with storage conditions and type of tea. Black tea has a longer shelf life than green tea. An exception, Pu-erh tea improves with age. Tea stays freshest when stored in a dry, cool, dark place in an air-tight container. Black tea stored in a bag inside a sealed opaque canister may keep for two years. Green tea loses its freshness more quickly, usually in less than a year. Gunpowder tea, its leaves being tightly rolled, keeps longer than the more open-leafed Chun Mee tea. Storage life for all teas can be extended by using desiccantpackets or oxygen absorbing packets, and by vacuum sealing.
When storing green tea, discreet use of refrigeration or freezing is recommended. In particular, drinkers need to take precautions against temperature variation.[67]
Improperly stored tea may lose flavor, acquire disagreeable flavors or odors from other foods, or become moldy.

[edit]Gallery

[edit]See also

[edit]References


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[edit]Bibliography

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  • Eelco Hesse (1982), Tea: The eyelids of Bodhidharma, Prism Press.
  • Hobhouse, Henry (2005). Seeds of Change: Six Plants that Transformed Mankind. Shoemaker & Hoard. ISBN 1-59376-049-3.
  • Kiple, Kenneth F.; Ornelas, Kriemhild Coneè, eds. (2000). The Cambridge World History of Food. 1. Cambridge: Cambridge University Press. ISBN 0521402166..
  • Lu Yu (陆羽): Cha Jing (茶经) Translated and Introduced by Francis Ross. The Classic of Tea. Boston: Little, 1974. x, 177p. ISBN 0316534501; Reprinted: Ecco Press, 1997. ISBN 0880014164.
  • Lysaght, Patricia. "When I makes Tea, I makes Tea: the case of Tea in Ireland". Ulster Folklife, Vol. 33, 1987
  • Roy Moxham (2003), Tea: Addiction, Exploitation, and Empire
  • Victor H. Mair and Erling Hoh. The True History of Tea. New York; London: Thames & Hudson, 2009. ISBN 9780500251461.
  • Mondal, T.K. (2007). "Tea". In Pua, E.C.; Davey, M.R.. Biotechnology in Agriculture and Forestry. 60: Transgenic Crops V. Berlin: Springer. pp. 519–535. ISBN 3540491600..
  • Nye, Gideon (1850). Tea: and the tea trade Parts first and second. New York: Printed by G.W. Wood.
  • Jane Pettigrew (2002), A Social History of Tea
  • Stephan Reimertz (1998): Vom Genuß des Tees: Eine heitere Reise durch alte Landschaften, ehrwürdige Traditionen und moderne Verhältnisse, inklusive einer kleinen Teeschule (In German)
  • James Norwood Pratt (2005), Tea Dictionary
  • Sanyal, Amitava (April 13, 2008). "How India came to be the largest tea drinking nation". Hindustan Times (New Delhi): p. 12.[dead link].
  • Karmakar, Rahul (April 13, 2008). "The Singpho: The cup that jeers".Hindustan Times (New Delhi): p. 12..
  • Lester Packer, Choon Nam Ong, Barry Halliwell (2004): Herbal and Traditional Medicine: Molecular Aspects of Health, CRC Press, ISBN 0-8247-5436-0
  • Tunstal-Pedoe, M. (1999). "Coffee and tea consumption in the Scottish Heart Health Study follow up: conflicting relations with coronary risk factors, coronary disease, and all cause mortality". Journal of epidemiology and community health 53 (8): 481–487.doi:10.1136/jech.53.8.481. PMC 1756940. PMID 10562866.
  • Yamamoto, T; Kim, M; Juneja, L R (1997). Chemistry and Applications of Green Tea. CRC Press..
  • "Tea and Health". Nutrition (Burbank, Los Angeles County, Calif.) 15(11–12): 946–949. Nov-Dec 1999. PMID 10575676.

[edit]External links

Wikiquote has a collection of quotations related to: Tea
 The Wiktionary entry for tea  Media related to Tea at Wikimedia Commons
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