Green tea

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Green tea (緑茶) is tea that has undergone minimal oxidation during processing. Green tea is popular in China and Japan, and recently has become more popular in the West, which traditionally drank only black tea.

Table of contents

1 Chinese green teas
2 Japanese green teas
3 Health claims
4 External links

Chinese green teas

Grades of Chinese green tea (绿茶 lÃÂÃÂ¼cha) include:

Lung ching ("dragon well") is a famous tea from the town of Lung Ching, near Hangzhou, Zhejiang Province. Lung ching is further divided into 7 grades: Superior (qiqiang), Special (queshe) and then 1 down to 5.
Mao feng ("Mao Peak") is a famous tea from Mount Huangshan.
Pearl tea (not to be confused with pearl milk tea) consists of tea leaves rolled into balls. The term gunpowder tea is used in English for higher grades of pearl tea.
Chun mee ("precious eyebrows"), the most common type in China, is named after the shape of the tea leaves.
Jasmine tea
Hyson is an early-harvested tea whose leaves are twisted in a long, thin style.

Japanese green teas

Green tea (緑茶 ryokucha) is so ubiquitous in Japan that it is more commonly known as "honorable tea" (お茶, ocha) and even "Japanese tea" (日本茶, nihoncha). Types of tea are commonly graded depending on the quality and the parts of the plant used.

Matcha (抹茶, "rubbed tea") is the highest grade of green tea, used primarily in the tea ceremony. The tea bushes are shaded from sunlight for 3 weeks before harvesting, producing amino acids that sweeten the taste. The leaves are then ground to a fine powder, which is simply blended in lukewarm water for consumption.
Gyokuro (玉露, "jewel dew") is unground matcha leaf, prepared for consumption by infusion.
Sencha (煎茶, "broiled tea") is the most common type of green tea in Japan, accounting for 75% of production. It is made from the young leaves of uncovered plants.
Shincha (新茶, "new tea") is newly harvested, lightly steamed sencha. It is aromatic but highly perishable, lasting for only about 3 months.
Genmaicha (玄米茶, "brown rice tea") is sencha mixed with roasted brown rice.
Bancha (番茶, "number tea") is from the last harvest of the season. It is milder, cheaper and contain less caffeine than other varieties.
Hojicha (焙じ茶, "roasted tea") is prepared by roasting bancha leaves.
Kukicha (茎茶, "stem tea") is made from tea twigs instead of leaves. It contains only a tenth of the caffeine of leaf tea and its flavor is commonly compared to oolong teas.

There are large variations in both price and quality within these broad categories, and there are many specialty green teas that fall outside this spectrum.

Health claims

A number of health claims have been made for green tea [1], claiming that its polyphenol content has antioxidant properties that can help prevent cancer.

An article in New Scientist magazine (20 March 2004) mentions that numerous studies suggest that green tea protects against a range of cancers, including lung, prostate and breast cancer. The secret is the antioxidant epigallocatechin gallate (EGCG), according to Hirofumi Tachibana's team at Kyushu University in Japan. Their research showed that growth of human lung cancer cells that have a cell receptor called 67 LR is slowed significantly after drinking just two or three cups of green tea, which contains EGCG. The research also showed that 67 LR is involved in the propagation of prion diseases such as mad cow disease in humans. So knowledge of EGCG's effect on 67 LR might have implications in the treatment of these diseases too. (Full report in Nature Structural and Molecular Biology, DOI:10.1038/nsmb743).

According to the U.S. National Cancer Institute, in laboratory studies using animals, catechins scavenged oxidants before cell damage occurred, reduced the number and size of tumors, and inhibited the growth of cancer cells. White tea is said to be even more effective. However, human studies have proven more contradictory, perhaps due to such factors as variances in diet, environments, and populations.

External links

http://www.cancer.gov/newscenter/pressreleases/tea
http://www.healthfinder.gov/news/newsstory.asp?docID=507999