Tea is an aromatic beverage commonly prepared by pouring hot or boiling water over cured leaves of the tea plant, Camellia sinensis. After water, tea is the most widely consumed beverage in the world. It has a cooling, slightly bitter, and astringent flavour that many people enjoy.
Tea likely originated in China as a medicinal drink. It was first introduced to Portuguese priests and merchants in China during the 16th century. Drinking tea became popular in Britain during the 17th century. The British introduced it to India, in order to compete with the Chinese monopoly on the product.
Tea has long been promoted for having a variety of positive health benefits. Recent studies suggest that green tea may help reduce the risk of cardiovascular disease and some forms of cancer, promote oral health, reduce blood pressure, help with weight control, improve antibacterial and antivirasic activity, provide protection from solar ultraviolet light, and increase bone mineral density. Green tea is also said to have “anti-fibrotic properties, and neuroprotective power.” Additional research is needed to “fully understand its contributions to human health, and advise its regular consumption in Western diets.”
Tea catechins have known anti-inflammatory and neuroprotective properties, help regulate food intake, and have an affinity for cannabinoid receptors, which may suppress pain and nausea and provide calming effects.
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.
Tea contains L-theanine, an amino acid whose 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 meditative practice.
The phrase “herbal tea” usually refers to infusions of fruit or herbs made without the tea plant, such as rosehip tea, chamomile tea, or rooibos tea. Alternative phrases for this are tisane or herbal infusion, both bearing an implied contrast with “tea” as it is construed here.
Cultivation and harvesting
Camellia sinensis is an evergreen plant that grows mainly in tropical and subtropical climates. Some varieties can also tolerate marine climates and are cultivated as far north as Pembrokeshire in the British mainland and Washington in the United States.
Tea plants are propagated from seed and cutting; it takes about 4 to 12 years for a tea plant to bear seed, and about three years before a new plant is ready for harvesting. In addition to a zone 8 climate or warmer, tea plants require at least 127 cm (50 inches) of rainfall a year and prefer acidic soils. Many high-quality tea plants are cultivated at elevations of up to 1,500 m (4,900 ft) above sea level. While at these heights the plants grow more slowly, they acquire a better flavour.
Two principal varieties are used: Camellia sinensis var. sinensis, which is used for most Chinese, Formosan and Japanese teas, and Camellia sinensis var. assamica, used in Pu-erh and most Indian teas (but not Darjeeling). Within these botanical varieties, there are many strains and modern clonal varieties. Leaf size is the chief criterion for the classification of tea plants, with three primary classifications being,Assam type, characterised by the largest leaves; China type, characterised by the smallest leaves; Cambodian type, characterised by leaves of intermediate size.
A tea plant will grow into a tree of up to 16 m (52 ft) if left undisturbed, 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.
Only the top 1–2 inches of the mature plant are picked. These buds and leaves are called flushes. A plant will grow a new flush every seven to fifteen days during the growing season. Leaves that are slow in development tend to produce better-flavoured teas.Pests of tea include mosquito bugs that can tatter leaves, so they may be sprayed with insecticides.
Organic tea cultivation is endorsed by governments, corporations, and foundations in tea-growing countries, due to the danger of insecticides to human health and the potential for soil pollution. Naturally occurring mined products are used for soil fertilization. Leaf pests and diseases are controlled with the use of biological control agents, which are prepared or extracted without the use of chemical solvents.
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