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Green Tea

Green Tea - General Science Questions and Layperson Board

Green Tea - General Science Questions and Layperson Board


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  #1  
Old 11-19-2007, 01:12 PM
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Default Green Tea



Hi
Tea is grown in about 30 countries but is consumed worldwide, although at greatly varying levels. It is the most widely consumed beverage aside from water with a per capita worldwide consumption of approximately 0.12 liter per year. Tea is manufactured in three basic forms. Green tea is prepared in such a way as to preclude the oxidation of green leaf polyphenols. During black tea production oxidation is promoted so that most of these substances are oxidized. Oolong tea is a partially oxidized product. Of the approximately 2.5 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea. Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. Fresh tea leaf is unusually rich in the flavanol group of polyphenols known as catechins which may constitute up to 30% of the dry leaf weight. Other polyphenols include flavanols and their glycosides, and depsides such as chlorogenic acid, coumarylquinic acid, and one unique to tea, theogallin (3-galloylquinic acid). Caffeine is present at an average level of 3% along with very small amounts of the other common methylxanthines, theobromine and theophylline. The amino acid theanine (5-N-ethylglutamine) is also unique to tea. Tea accumulates aluminum and manganese. In addition to the normal complement of plant cell enzymes, tea leaf contains an active polyphenol oxidase which catalyzes the aerobic oxidation of the catechins when the leaf cell structure is disrupted during black tea manufacture. The various quinones produced by the enzymatic oxidations undergo condensation reactions which result in a series of compounds, including bisflavanols, theaflavins, epitheaflavic acids, and thearubigens, which impart the characteristic taste and color properties of black tea. Most of these compounds readily form complexes with caffeine. There is no tannic acid in tea. Thearubigens constitute the largest mass of the extractable matter in black tea but their composition is not well known. Proanthocyanidins make up part of the complex. Tea peroxidase may be involved in their generation. The catechin quinones also initiate the formation of many of the hundreds of volatile compounds found in the black tea aroma fraction. Green tea composition is very similar to that of the fresh leaf except for a few enzymatically catalyzed changes which occur extremely rapidly following plucking. New volatile substances are produced during the drying stage. Oolong tea is intermediate in composition between green and black teas.
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  #2  
Old 10-16-2009, 11:14 PM
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Default Re: Green Tea

Interesting
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Old 03-23-2010, 06:41 AM
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Default Re: Green Tea

I am addicted to drinking green tea.. Many say that it is a healthy alternative to water.
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Old 08-04-2010, 07:41 PM
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Default Re: Green Tea

Good to know!
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Old 08-05-2010, 02:02 AM
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Default Re: Green Tea

I like green tea, too. I think they are good for ourselives and health!
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Old 12-28-2010, 06:06 PM
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Default Re: Green Tea

Are Green Tea and Black Tea both produced from the same plant?
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Old 05-30-2011, 12:50 PM
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Default Re: Green Tea

HI,
Nice information posted here.. Really very interesting..

RayMeds.com
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Old 06-02-2011, 07:58 AM
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Smile Re: Green Tea

Its informative one provides a lots of data on topic also provide more information on topic.
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Old 07-01-2011, 07:30 AM
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Default Re: Green Tea

Thanks, its really interesting. I take green tea. I heard that it is good for health.
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  #10  
Old 07-05-2011, 02:43 PM
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Default Re: Green Tea

That's interesting. The tea is good for our health. It is really useful.
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