Green tea is a type of tea made from the leaves and buds of the Camellia sinensis that have not undergone the withering and oxidation process that creates oolong teas and black teas. Green tea originated in China in the late 1st millennium BC, and since then its production and manufacture has spread to other countries in East Asia.
Several varieties of green tea exist, which differ substantially based on the variety of C. sinensis used, growing conditions, horticultural methods, production processing, and time of harvest. While it may slightly lower blood pressure and improve alertness, consuming green tea does not provide health effects. Excessive intake of green tea extracts can cause liver damage, interfere with prescription drugs, and produce gastrointestinal discomfort.
History
Tea consumption has its legendary origins in China during the reign of mythological Emperor Shennong.
A book written by Lu Yu in 618–907 AD, The Classic of Tea (), is considered important in green tea history. Another early text, the Book of Tea (Kissa Yōjōki, lit. Record [of] Drinking Tea [for] Nourishing Life),written by Zen priest Eisai in 1211, discusses tea drinking in relation to health and the five viscera.
Steeping, brewing and serving
Steeping, or brewing, is the process of making tea from leaves and hot water, generally using of tea per of water or about of green tea per cup. Steeping temperatures range from to and steeping times from 30 seconds to three minutes.
Generally, lower-quality green teas are steeped hotter and longer while higher-quality teas are steeped cooler and shorter, but usually multiple times (2–3 typically). Higher-quality teas like gyokuro use more tea leaves and are steeped multiple times for short durations. Steeping too hot or too long results in the release of excessive amounts of tannins, leading to a bitter, astringent brew, regardless of initial quality. The brew's taste is also affected by the steeping technique; two important techniques are to warm the steeping container beforehand to prevent the tea from immediately cooling down, and to leave the tea leaves in the pot and gradually add more hot water during consumption.
Production In 2013, global production of green tea was approximately 1.7 million tonnes, with a forecast to double in volume by 2023. As of 2015, China provided 80% of the world's green tea market, leading to its green tea exports rising by 9% annually, while exporting 325,000 tonnes in 2015. In 2015, the US was the largest importer of Chinese green tea (6,800 tonnes), an increase of 10% over 2014, and Britain imported 1,900 tonnes, 15% more than in 2014.
Growing, harvesting and processing
Green tea is processed and grown in a variety of ways, depending on the type of green tea desired. As a result of these methods, maximum amounts of polyphenols and volatile organic compounds are retained, affecting aroma and taste. The growing conditions can be broken down into two basic types − those grown in the sun and those grown under the shade. The green tea plants are grown in rows that are pruned to produce shoots in a regular manner, and in general are harvested three times per year. The first flush takes place in late April to early May. The second harvest usually takes place from June through July, and the third picking takes place in late July to early August. Sometimes, there will also be a fourth harvest. The first flush in the spring brings the best-quality leaves, with higher prices to match.
Green tea is processed after picking using either artisanal or modern methods. Sun-drying, basket or charcoal firing, or pan-firing are common artisanal methods. Oven-drying, tumbling, or steaming are common modern methods. Processed green teas, known as aracha, are stored under low humidity refrigeration in 30- or 60-kilogram paper bags at . This aracha has yet to be refined at this stage, with a final firing taking place before blending, selection and packaging take place. The leaves in this state will be re-fired throughout the year as they are needed, giving the green teas a longer shelf-life and better flavour. The first flush tea of May will readily store in this fashion until the next year's harvest. After this re-drying process, each crude tea will be sifted and graded according to size. Finally, each lot will be blended according to the blending order by the tasters and packed for sale.
Import of radioactive Japanese tea On 17 June 2011, at Charles de Gaulle airport in Paris, France, radioactive caesium of 1,038 becquerels per kilogram was measured in tea leaves imported from Shizuoka Prefecture, Japan as a result of the Fukushima Daiichi nuclear disaster on 11 March, which was more than twice the restricted amount in the European Union of 500 becquerels per kilogram. The government of France announced that they rejected the leaves, which totalled ."." (Japanese) Asahi Shimbun. 2011-06-18. Retrieved 2011-06-19.
In response, the governor of Shizuoka Prefecture, Heita Kawakatsu, stated: "there is absolutely no problem when they [people] drink them because it will be diluted to about 10 becquerels per kilogram when they steep them even if the leaves have 1,000 becquerels per kilogram;" a statement backed by tests done in Shizuoka."." (Japanese) Asahi Shimbun. 2011-06-18. Retrieved 2011-06-19. Japanese Minister for Consumer Affairs and Food Safety Renhō stated on 3 June 2011 that "there are cases in which aracha are sold as furikake and so on and they are eaten as they are, therefore we think that it is important to inspect tea leaves including aracha from the viewpoint of consumers' safety."
In 2018, the US Food and Drug Administration updated its import status on Japanese products deemed to be contaminated by radionuclides, indicating that tea from the Ibaraki prefecture had been removed from the list by the Government of Japan in 2015.
Green tea across East Asia
Mainland China and Taiwan
Loose leaf green tea has been the most popular form of tea in China since at least the Southern Song dynasty. While Chinese green tea was originally steamed, as it still is in Japan, after the early Ming dynasty it has typically been processed by being pan-fired in a dry wok. Other processes employed in China today include oven-firing, basket-firing, tumble-drying and sun-drying. Green tea is the most widely produced form of tea in China, with 1.42 million tons grown in 2014.
Popular green teas produced in China today include: Green snail spring () Produced in Jiangsu, this tea is named after the shape of the leaves, which are curled like snails. Precious eyebrows () Known in English by its Cantonese name, and popular outside China. It has a plum-like flavour. Gunpowder tea () "Pearl tea", also called Gunpowder tea, is a form of tea which is tumble-dried so that each leaf is rolled into a small pellet that resembles gunpowder. Yellow Mountain fur peak () A type of maofeng tea grown in the microclimate of the Huangshan mountain range in Anhui province. Maofeng teas are harvested by plucking intact two equal-sized leaves and a bud together. Dragon Well ()Grown near Hangzhou in Zhejiang province, Longjing is the most well-known pan-fired Chinese green tea. Its flavour derives partly from the terroir of the region in which it is produced. Lu'an melon seed () Grown in Anhui province. Unlike typical Chinese teas, two leaves are plucked separately from each branch, with no bud and no stems. Harvested later in the season, it has a grassier flavour than typical Chinese green teas. Peaceful monkey leader () Grown in Anhui province. Uses a cultivar with an unusually large leaf. The production process flattens the tea leaves, creating the so-called "two knives and a pole" shape from the leaves and stem. Tippy green () A type of maojian tea grown in Xinyang, Henan province. Maojian teas are harvested by plucking a bud and one leaf together. Anji white () A type of green tea from Anji Sweet dew of Mengding () A yellowish-green tea with sweet aftertaste from Mending mountain in Sichuan Duyun Maojian () One of the famous Chinese teas which was a favourite of Mao Zedong.Xie WeiBin, Xie WeiBin, Zhang GuoZhou Zhang GuoZhou, and Song LiSha Song LiSha. "Breeding of native tea varieties of Duyun Maojian." (2011): 33-38. Cloud tea () A type of green tea originally cultivated in Le Mountain (), named for the mountain clouds. It is mentioned in The Classic of Tea and is one of the famous Chinese teas.
Japan
Tea seeds were first brought to Japan in the early 9th century by the Buddhist monks Saicho and Kūkai. During the Heian period (794–1185), Emperor Saga introduced the practice of drinking tea to the imperial family. The Zen Buddhist priest Eisai (1141–1215), founder of the Rinzai school of Buddhism, brought tea seeds from China to plant in various places in Japan. Eisai advocated that all people, not just Buddhist monks and the elite, drink tea for its health benefits.
The oldest tea-producing region in Japan is Uji, located near the former capital of Kyoto. It is thought that seeds sent by Eisai were planted in Uji, becoming the basis of the tea industry there. Today, Japan's most expensive premium teas are still grown in Uji. The largest tea-producing area today is Shizuoka Prefecture, which accounts for 40% of total Japanese sencha production. Other major tea-producing regions include the island of Kyushu and the prefectures of Shiga, Gifu, and Saitama in central Honshu.
All commercial tea produced in Japan today is green tea, though for a brief period black tea was also produced in the late 19th and early 20th centuries. Japanese tea production is heavily mechanized, and is characterized by the use of modern technology and processes to improve yields and reduce labour. Because of the high cost of labour in Japan, only the highest quality teas are plucked and processed by hand in the traditional fashion.
Japanese green teas have a thin, needle-like shape and a rich, dark green colour. Unlike Chinese teas, most Japanese teas are produced by steaming rather than pan-firing. This produces their characteristic colour, and creates a sweeter, more grassy flavour. A mechanical rolling/drying process then dries the tea leaves into their final shape. The liquor of steamed Japanese tea tends to be cloudy due to the higher quantity of dissolved solids.
Most Japanese teas are blended from leaves grown in different regions, with less emphasis on terroir than in the Chinese market. Because of the limited quantity of tea that can be produced in Japan, the majority of production is dedicated to the premium tea market. Cheaper bottled teas and tea-flavoured food products usually use lower-grade Japanese-style tea produced in China.
Although a variety of commercial tea cultivars exist in Japan, the vast majority of Japanese tea is produced using the Yabukita cultivar developed in the 1950s.
Popular Japanese green teas include: Bancha () A lower-grade tea plucked from the same bushes used to produce sencha. It has a somewhat bolder flavour, and is plucked each season after sencha production is finished. Genmaicha () Made by combining sencha tea leaves with toasted puffs of rice. Gyokuro () Grown under shade for three weeks prior to plucking, gyokuro is one of the most exclusive varieties of tea produced in Japan. The shading technique imparts a sweeter flavour, and produces a particularly rich colour thanks to the higher amounts of chlorophyll in the shaded leaf. Gyokuro tea is associated with the Uji region, the first tea-growing region in Japan. It is often made using smaller-leaf cultivars of the tea plant. Hōjicha () This type of tea is made by roasting sencha or bancha leaves with kukicha twigs. Kabusecha () Similar to gyokuro, kabusecha is shaded for only a week prior to plucking. Its flavour is somewhat between that of gyokuro and normal sencha. Kukicha () A blended tea made of sencha leaves and stems.