Sabtu, 20 April 2013

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THE TEA PLANT

Camellia sinensis, the tea plant, is the species of plant whose leaves and leaf buds are used to produce tea. It is of the genus Camellia. A genus of flowering plants in the family Theaceae. White tea, green tea, oolong, pu-erh tea and black tea are all harvested from this species, but are processed differently to attain different levels of oxidation. Kukicha (twig tea) is also harvested from camellia sinensis, but uses twigs and stems rather than leaves.
The name sinensis means Chinese in Latin. Camellia is taken from the Latinized name of Rev. Georg Kamel, S.J. (1661-1706), a Czech-born Jesuit priest who became both a prominent botanist and a missionary to the Philippines. Though Kamel did not discover or name the plant, Carl Linnaeus, the creator of the system of taxonomy still used today, chose his name for the genus of this tree to honor Kamel's contributions to science. Older names for the tea plant include Thea bohea, Thea sinensis and Thea viridis.
Camellia sinensis is native to Southeast Asia, but is today cultivated across the world, in tropical and subtropical regions. It is an evergreen shrub or small tree that is usually trimmed to below two meters (six feet) when cultivated for its leaves. It has a strong taproot. The flowers are yellow-white, 1 to 1.5 inches in diameter, with 7 to 8 petals. The seeds can be pressed to yield oil.
The leaves are about 4-15 cm long and 2-5 cm broad. Fresh leaves contain about 4% caffeine. The young, light green leaves are preferably harvested for tea production; they have short white hairs on the underside. Older leaves are darker green. Different leaf age produce differing tea qualities, since their chemical compositions are different. Usually, the tip (bud) and the first two to three leaves are harvested for processing. This hand picking is repeated every one to two weeks.
Tea is known as nature’s 'wonder drug'. Of late, tea and its healthy benefits have been receiving wide attention in the media. The ability of tea to promote good health has long been believed in many countries, especially Japan, China, India, and even England.


CULTIVATION
Camellia sinensis is mainly cultivated in tropical and sub-tropical climates, in areas with at least 50 inches of rainfall a year. However, it is commercially cultivated from the equator to as far north as Cornwall on the UK mainland. Many high quality teas are grown at high elevations, up to 1500 meters (5,000 ft), as the plants grow more slowly and acquire a better flavour.
Tea plants will grow into a tree if left undisturbed, but cultivated plants are pruned to waist height for ease of plucking. Two principal varieties are used, the small-leaved Chinese variety plant (C. sinensis sinensis) and the large-leaved Assamese plant (C. sinensis assamica), used mainly for black tea.

INDIAN TEAS
Indian teas are generally classified by the region they are grown in; the three main tea-producing regions in India are Darjeeling, Assam and Nilgiri.
Because of the exquisite growing conditions, Darjeeling tea is considered by tea lovers to be the finest of the Indian teas. Unlike almost all other Indian teas, Darjeeling uses the Chinese variety (C. sinensis sinensis), which was brought to India in the 19th century by British planters.
Assam is the largest producing area in India, at 473,000 metric tons annually. Assam has 271,768 hectares of tea gardens with 43,293 estates producing tea. Assam tea has a rich taste (often described as 'malty') and is frequently used as the basis for "breakfast" tea blends.
Nilgiri tea is grown in the South Indian Blue Mountain range. This growing region covers 62,039 hectares and has 62,145 tea estates. Annual tea production is approximately 120,000 tons.

CHINESE TEAS
The Chinese plant (sometimes called C. sinensis var. sinensis) is a small-leaved bush with multiple stems that reaches a height of some 3 meters. It is native to south-east China. The first tea plant to be discovered, recorded and used to produce tea three thousand years ago, it yields some of the most popular teas.
C. sinensis var. waldenae was considered a different species, Camellia waldenae by S.Y.Hu, but it was later identified as a variety of C. sinensis. This variety is commonly called Walden's Camellia. It is seen on Sunset Peak and Tai Mo Shan in Hong Kong. It is also distributed in Guangxi Province, China.


MEDICAL USES
• The leaves have been used in traditional Chinese medicine (TCM), and other medical systems to treat asthma (functioning as a bronchodilator), angina pectoris, peripheral vascular disease, and coronary artery disease. Tea extracts have become field of interest, due to their notional antibacterial activity. Especially the preservation of processed organic food and the treatment of persistent bacterial infections are being investigated.
• Green tea leaves and extracts have shown to be effective against bacteria responsible for bad breath.
• The tea component epicatechin gallate is being researched because in-vitro experiments showed that it can reverse methicillin resistance in bacteria like Staphylococcus aureus. If confirmed, this means that the combined intake of a tea extract containing this component will enhance the effectiveness of methicillin treatment against some resistant bacteria.

TEA : HEALTH BENEFITS AND WONDERS
Tea is the second most widely consumed beverage in the world, exceeded only by the most necessary of all liquids - water. Tea is an integral part of everyday societal life in many of the world’s most populous countries. This has made tea the most popular beverage for a huge swath of the world’s people.
Tea is prepared from linder leaves, leaf buds and tender stalks of different varieties of the warm-weather evergreen known as camellia sinensis.


Green Tea Lowers the Risk of Cancer.
Many studies have shown that people who drink green tea have significantly lower risk of cancer. Green Tea polyphenols are potent antioxidants, especially in the brain. Some studies show that the polyphenols most prevalent in green tea, the catechins, are far more potent in suppressing free radicals than vitamins C or E.
The ability of green tea to prevent cancer is so well established that new studies are testing green tea as a potential cancer therapy. Green tea may be especially protective against lung cancer in former and current cigarette smokers.
Green tea has been shown to counteract both the initiation and promotion of carcinogenesis. Some studies have shown that green tea blocks the formation of certain tumors. If green tea's only benefit were to reduce the risk of cancer, it would be well worth taking as a beverage or supplement.

Green Tea Lowers Cholesterol and Thus, The Risk of Stroke and Heart Diseases.
Green Tea has been shown to lower LDL cholesterol and serum triglyceride levels. The potent antioxidant effects of green tea inhibit the oxidation of LDL cholesterol in the arteries. It plays a major contributory role in the formation of atherosclerosis.
The formation of blood clots, also known as thrombosis, is the leading cause of heart attack and stroke. Green Tea has been proven to exhibit abnormal blood clot formation as effectively as aspirin. When looking at coagulation risk factors in the blood, green tea specifically inhibits platelet aggregation and adhesion via effects that differ from those of aspirin.


Green Tea Lowers Blood Pressure.
Green Tea blocks the effects of angiotension-converting enzyme (ACE), an enzyme secreted by the kidneys, which is a significant cause of hypertension. By blocking the effects of ACE, blood pressure is reduced significantly, and with it, the risk of heart attacks and strokes.
Published studies have shown lowered blood pressure in animals and humans that are given green tea extracts. If you will be using green tea to treat hypertension, do so only under the supervision of a competent medical professional. Regular testing of your blood pressure is mandatory.


Green Tea Prevents Tooth Decay.
The formation of dental plaque, bacterial colonies that form on tooth surfaces causing tooth decay, has been shown to be inhibited by catechins. Tea has been shown to inhibit Streptococcus mutans, a major bacteria involved with decay. A reduction of the bacterial cell membrane fluidity, induced by the catechins, results in the antiplaque activity. Tea also has been shown to have a positive effect in fighting gum disease.
Numerous studies have trumpeted the cardiovascular benefits of green tea, the beverage of choice in much of the Far East. But elsewhere in the world, particularly in Europe and the Middle East, black tea reigns supreme, and fewer studies have examined its heart-healthy properties.
In terms of its rich antioxidant properties, black tea comes next to green tea. The most commonly used and the most popular tea in the West, black tea is originally green tea with the leaves further dried - this changes its color and taste. Black Tea undergoes full oxidation and fermentation. The leaves thus turn black and receive their strong, typical flavor. The oxidation process is stopped once the aroma and flavor develops completely. The leaves are further crushed to various sizes, sorted out and stored according to their sizes.
Black tea is the foundation upon which the popular varieties of English tea are derived from. And many might be delighted to find out that black tea, aside from being an enjoyable drink, can actually be good for the health.
Recent studies in leading medical journals declare black tea a potential heart tonic, cancer blocker, fat buster, immune stimulant, arthritis soother, virus fighter and cholesterol detoxifier. Not bad for a lowly shrub soaked in a little hot water.
"Tea is beating all scientific expectations as the most potent health beverage ever," says researcher John Weisburger at the American Health Foundation. "The many ways tea can promote health is truly astonishing."
Here’s how black tea can potentially benefit your health:
Black Tea Saves arteries. Drinking black tea helps prevent deadly clogging of arteries and reverses poor arterial functioning that can trigger heart attacks and strokes. In arecent test, Joseph Vita, M.D., of the Boston University School of Medicine, had heart patients drink either plain water or four cups of black tea daily. In a month, impaired blood vessel functioning (a risk factor for heart attack and strokes) improved about 50% in the black tea drinkers.
Black Tea Inhibits cancer growth. Tea has long been tied to a lower risk of stomach, colon and breast cancer, although the connection is not proven. Now lab studies find that black tea chemicals actually may stop cancer growth. Rutgers University researchers showed that a compound in black tea called TF-2 caused colorectal cancer cells to "commit suicide"; normal cells were unaffected.
Black Tea Tames inflammation. TF-2, the newly discovered anti-cancer compound in black tea, suppresses the Cox-2 gene that triggers inflammation, says research at Rutgers.
Black Tea Wipes out viruses. Previous tests prove black tea can neutralize germs, including some that cause diarrhea, pneumonia, cystitis and skin infections. New research by Milton Schiffenbauer of Pace University finds that black and green tea deactivates viruses, including herpes. When you drink tea, he says, chances are good you will wipe out viruses in your mouth.





















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