Green tea

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Green tea, China Gunpowder
Green tea in Gaiwan
A tea plantation

Green tea or green tea ( Japanese 緑茶 ryokucha , Chinese  綠茶  /  绿茶 , pinyin lǜchá ) is a way of making tea . Unlike black tea, the tea leaves are not fermented . Because of the different processing, the leaves of Camellia sinensis are preferred to the assamica variety for green tea , as the small-leaved, more tender variety is better suited. Green tea differs from black tea, among other things, in the preparation, taste, ingredients and effects of the infusion.

Manufacturing

After the freshly picked leaves have wilted, briefly heating, roasting or steaming the tea leaves prevents oxidation. For this reason, almost all of the active ingredients present in the fresh leaf are retained. The conversion of the content u. a. in flavorings is prevented. Like black tea, green tea is also rolled, but here only to make the tea leaf pliable for further processing and to clear the way for the ingredients into the cup.

history

The tea plant has been grown in China for several thousand years . There was in the 6th century BC This new variant of the processing of tea was also produced. During the Chinese Tang Dynasty , tea pressed into bricks or other shapes was roasted, grated into powder, and made with boiling water. The poet Lu Yü described this in detail in 780 AD. The preparation was refined in the subsequent Song dynasty ; the tea leaves, after steaming and drying, went straight to stone mills and were ground to powder. In the 8th century, Buddhist monks brought tea to Japan from China . The form of tea preparation with ground green tea, which was common in China at the time, has been further developed into the Japanese tea ceremony in Japan since the Nara period . Traditionally, tea leaves ( matcha ) ground into fine dust in stone mills are whipped in hot water with a tea whisk . At the time of the Ming Dynasty , the method of brewing tea leaves directly in a teapot emerged - today the most common form of preparation worldwide. During this time (16th and 17th centuries) green tea also spread in Europe.

ingredients

The most important ingredient in tea is the stimulating caffeine , which used to be referred to in connection with tea as Tein , Teein or Thein . The caffeine content varies significantly depending on the type of green tea. Basically, the Japanese varieties Gyokuro and Sencha have the highest values ​​in tea water, and Kukicha and Bancha have the lowest values. Further components of the tea leaves are catechins , the most important representatives are epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and epigallocatechin gallate (EGCG). Most of the health benefits of green tea are attributed to the catechins. However, the catechins are also the substances that give tea its bitter taste.

The amino acids in the tea leaves are important for the taste of green tea, especially the theanine . The amino acids make up to six percent of the dry mass of the tea leaves. The amino acid content can be increased in a targeted manner during cultivation by shading the tea plants in spring.

Other ingredients are vitamin A , vitamin B , vitamin B2 , calcium , potassium , phosphates , magnesium , copper , zinc , nickel , carotenes and fluoride . Certain ingredients are not particularly important for absorption .

Green tea contains more tannins ( tannins ) than black tea . That's why it tastes tart than this. The tannins have a calming effect on nervous stomach and intestines and constipate on sluggish intestines.

sorts

Green tea, matcha
Green tea, China Maojian
Blossom of a tea plant (Longjing tea, "dragon fountain tea")

Chinese, pan-roasted varieties often have a slightly tart, smoky and often flowery taste, while Japanese, steamed green teas have a grassy, ​​fresh note. Jasmine tea is a green tea flavored with jasmine flowers .

Japan (selection, alphabetical)

  • Aracha (Japanese: 荒 茶), raw green tea
  • Bancha ("ordinary tea", Japanese: 番 茶), similar to Sencha (older leaves), low caffeine content, lots of calcium, is harvested in all tea-growing areas of Japan from the same plants as Sencha, in contrast to this (only the leaf Bud and the first two leaves) the fourth, fifth and sixth leaves are picked. This is why it is a simple tea and contains little caffeine as the young leaves contain more caffeine and give better qualities.
  • Fukamushicha (more subdued Sencha, Japanese: 深 蒸 し 茶)
  • Funmatsucha (instant ground tea, Japanese: 粉末 茶)
  • Gabalong (Japanese: ギ ャ バ ロ ン 茶), high gamma-amino acid content achieved through special natural processing
  • Genmaicha (Japanese: 玄 米 茶), tea enriched with roasted rice grains and thus flavored
  • Gyokuro ("noble dew drop", Japanese: 玉露), shade tea, grassy, ​​high caffeine content
  • Hōjicha , (Japanese: 焙 じ 茶) roasted Sencha / Bancha
  • Kabusecha (tea grown under the penumbra, Japanese: か ぶ せ 茶), a Sencha that grows under similar light conditions as the wild tea plant
  • Kamairicha (pan- roasted tea, Japanese: 釜 炒 り 茶)
  • Konacha (Japanese: 粉 茶)
  • Kukicha (Japanese: 茎 茶), high proportion of stems and leaf veins, grassy, ​​needle-shaped leaves, mild and low in caffeine
  • Matcha ("ground tea", Japanese: 抹茶), powder tea, shade tea from Tencha (base tea), high caffeine content
  • Mecha (Japanese: 芽茶)
  • Sencha ("steamed tea", Japanese: 煎茶), the most frequently drunk green tea in Japan, has different qualities from three harvest seasons (April / May first harvest, June / July second harvest, August / September third harvest). The earlier the harvest, the higher the quality, which does not only depend on the harvest time.
  • Shincha (new tea, Japanese: 新 茶)
  • Tamaryokucha (Japanese: 玉 緑茶), another form of roasted or steamed tea, variant: Yonkon
  • Tencha (Japanese: 碾 茶)

China (selection, alphabetical)

  • Bi Feng, fine leaf
  • Bi Luo Chun , deep green and finely twisted leaves, fresh aroma, light in the infusion
  • Chun Mee (“valuable eyebrow”), curved silvery leaf, strong, slightly smoky
  • Cris Cross, soft leaf tea with a jade green color
  • Gu Zhan Mao Jian
  • Gui Hua
  • Gunpowder ("gunpowder", formerly also called pearl tea), tea leaves rolled into balls, earthy
  • Li-Zi Xiang, golden yellow tea
  • Long Tseng, long, flat leaf
  • Lung Ching or Long Jing ("Dragon Fountain Tea", often referred to simply as "Dragon Tea", the translation being "Dragon Fountain" is correct), from Zhejiang Province , flat green leaves, jade green color, spicy scent, clear and yellow in the infusion
  • Mao Feng (Mao = hairy, Feng = pointed), tea from the high mountains, slightly twisted silvery leaves
  • Mao Feng Cris Cross, called a noble rarity, in the infusion yellow-green cup with finely sweet nuances
  • Mao Jian ("tips of hair")
  • Matcha (ground tea), powdered tea, shade tea, rich in EGCG catechins and caffeine
  • Mêng-Ting (Hidden Mountain Peak)
  • Moon Palace, spherical leaves, slightly tart flavor
  • Pan Long Ying Hao, soft, rolled leaf with lots of white tea tips
  • Pouchong (Taiwan), fruity aroma
  • Qingcheng, Sichuan Province
  • San Xia Mao Juan, slightly curled leaf
  • Sencha (煎茶), light and soft, yet spicy
  • Tian Mu Qing Ding, finely crafted tea leaf, jade green in the infusion
  • Tung-Ting, from Taiwan
  • Tuocha, slightly fermented Yunnan, spicy
  • Yin Gou, even leaf surrounded by soft fluff
  • Yong Xi Hou Qing, grew up on wild tea plants between orchid fields
  • Yuncui, is described as full-bodied, flowery, highly aromatic, handcrafted, long, deep green leaves
  • Yunnan green, mild, light taste

India

  • Nilgiri fragrant, light citrus note
  • Assam strong, malty
  • Darjeeling Muscatel note. First Flush: light cup, light and tangy, freshness reminiscent of asparagus Second Flush: Strong cup with a typical Muscatel note

Medical effects and studies

The medical efficacy of green tea has now been examined in over 100 clinical studies worldwide. However, they are often difficult to compare. Many alleged health-promoting effects cannot be proven: They are largely based on epidemiological studies, the interpretations of which are controversial, as well as on laboratory and animal experiments that cannot easily be transferred to humans - if only because the active ingredient, which is often the focus of attention Epigallocatechin gallate (EGCG) is hardly absorbed by the body during normal tea drinking.

A study from 2014 found that epigallocatechin gallate, the green tea 11 β -hydroxysteroid dehydrogenase 1 potently inhibits, therefore less cortisol is available, thus possibly parts of the health-promoting properties of green tea could be explained.

In the so-called Ohsaki study carried out in Japan and running for 11 years with 40,530 adults between the ages of 40 and 79, it was found that the drink has positive cardiovascular properties and is therefore life-extending. According to the study, the death rate among male test participants who drank at least five cups a day fell by 12 percent and among women by 23 percent. In particular, deaths from cardiovascular diseases were less common, also more noticeable in women (31/22 percent). No reduction in cancer mortality was found in this study.

Some other studies indicate that regular consumption of green tea the risk of developing cancer of suffering can diminish, as in parts of the world where a lot of tea is drunk, the incidence than others for certain types of cancer is lower in the World. A preventive effect is attributed in particular to the polyphenols naturally contained in some types of tea (especially epigallocatechin gallate, EGCG).

A study on patients with prostate cancer , which was carried out at the Center for Human Nutrition at the David Geffen School of Medicine at UCLA , showed that the EGCG from the tea was detectable in the tumors and inhibited cell growth. The results suggest that green tea and black tea could help prevent prostate cancer.

The polyphenols and fluorides contained in black tea and especially in green tea reduce the risk of dental caries .

If you drink more than ten cups of green tea a day, you could damage your liver and kidneys. This is what Chung Yang and his colleagues at Rutgers University New Jersey claim in the journal Chemical Research in Toxicology after reviewing studies. Too high a dose of the polyphenols in green tea can be toxic, says Yang. So far, however, this thesis has not been confirmed in human studies.

In another Japanese study it was shown that both green tea and rooibos tea have a prophylactic effect against diabetic nephropathy . It is assumed that the polyphenols contained in green tea, or the flavonoids contained in rooibos , intercept free radicals . This may reduce the accumulation of glucose on the body's own proteins, which effectively protects the kidneys. Diabetic nephropathy is a kidney disease caused by diabetes mellitus . It is a common cause of kidney failure in diabetics.

Huntington's disease is an inherited, neuro-degenerative disease. Using model organisms, it was found that green tea can delay plaque formation, which leads to disease . The substance EGCG obtained from green tea is responsible for this. It is able to delay the clumping of the so-called HD protein. Transgenic flies to which the Huntington's disease gene was transferred also showed improved motility after ingestion of EGCG.

The Egyptian scientist Dr. Mervat Kassem found that antibiotics work significantly better if the patients also drink green tea. His research team tested the effect of this combination on the pathogens of 28 infectious diseases. The green tea increased the effect in all cases. Even some germs that no longer responded to antibiotics became vulnerable again.

Neurodegenerative diseases like Alzheimer's and Parkinson's are caused by the formation of amyloid fibrils . The substance EGCG contained in green tea prevents their formation by binding to the native, still unfolded polypeptide chains. As a result, harmless, spherical oligomers are formed instead of the toxic, fibrous amyloid fibrils .

In addition, studies in multiple sclerosis research indicate that EGCG can both protect nerve cells in the central nervous system from damage and regulate misdirected T lymphocytes , which are blamed for the disease. The course of experimental autoimmune encephalomyelitis - the animal model of multiple sclerosis - was significantly milder when EGCG was administered than in animals that received no EGCG. In order to achieve the dosages used in the studies by consuming green tea, one would have to ingest large amounts per day.

When milk is added, calcium oxalate precipitates as a poorly soluble salt and is excreted via the gastrointestinal tract. This reduces the risk of kidney stone formation. However, a study led by Verena Stangl (Charité Berlin) shows that the caseins in milk neutralize the vascular protective, anti-inflammatory and antioxidant effects of catechins (such as EGCG).

Researchers at Purdue University have also found that adding an acidic ingredient such as B. lemon juice or vitamin C helps to preserve the catechins in tea so that they do not disintegrate during digestion. So they can be absorbed even better by the body. Orange, lime and grapefruit juice as an addition have the same effect.

It could be shown that EGCG could prevent the entry of the hepatitis C virus into the liver cells in a laboratory test. Studies on humans are not yet available.

The consumption of green tea could also hinder certain medicines from working. A Japanese study from 2014 found that the consumption of green tea can reduce the plasma concentration of the beta blocker nadolol . Obviously, substances in tea reduce the absorption of the active ingredient in the intestine .

preparation

Green tea is brewed with water that is 70 to a maximum of 90 ° C, as water that is too hot makes the tea bitter or even inedible, depending on the variety. The water shouldn't be colder than 50 ° C. To do this, let the boiling water cool down for 10 minutes or mix it down with cold water.

As the temperature rises, the solubility of most of the tea ingredients improves - if the draw water is too cold, the ingredients cannot be dissolved in the infusion. For many varieties, 70 ° C is the right temperature for making tea. If you drink green tea for health reasons, please note the following: The heat-sensitive vitamin C contained in tea improves the absorption of the health- promoting polyphenols . On the other hand, scalding with 95 ° C hot water and a longer steeping time (ten minutes to one hour) improves the extraction of the polyphenols. Therefore, a little lemon juice can be added to the cooled tea to increase the vitamin C content.

There are more recent developments of semi-shade tea (Kabusecha), which can be infused with cold water with a correspondingly long steeping time ( Japanese : Mizudashi, English : coldbrew).

In East Asia , the tea leaves are left in the water longer. The taste changes over the time of drinking, which results in a very bitter tea residue after ten minutes of steeping. Pouring into a second, empty jug is not common in China. Chinese restaurants like to practice coating, while Korean restaurants don't.

You can infuse green tea several times. However, it should be noted that hotter water should be used for further infusions and the steeping time should be shortened.

In the tea culture in Northwest Africa , three infusions are usually common with the Gunpowder variety. Plenty of sugar and often a few fresh nano mint leaves are put into the teapot. The tea should be poured into the glasses from a great height or transferred several times so that the desired foam forms in the glass.

Trivia

In the crime novels by Christian von Ditfurth about Commissioner de Both, he only drinks the third green tea infusion.

literature

Web links

Commons : Green Tea  - Collection of pictures, videos and audio files

Individual evidence

  1. ^ Y. Wang, CT Ho: Polyphenolic chemistry of tea and coffee: a century of progress. In: Journal of Agricultural and Food Chemistry . Volume 57, Number 18, September 2009, pp. 8109-8114, doi: 10.1021 / jf804025c . PMID 19719133 . (Review).
  2. ↑ German Society for Nutrition e. V.
  3. ↑ How healthy is tea? SWR2 knowledge from October 25, 2018
  4. ↑ Jan Hintzpeter, Claudia Stapelfeld, Christine Loerz, Hans-Joerg Martin, Edmund Maser: Green Tea and One of Its Constituents, Epigallocatechine-3-gallate, Are Potent Inhibitors of Human 11β-hydroxysteroid Dehydrogenase Type 1. In: PLoS ONE. 9, 2014, p. E84468, doi: 10.1371 / journal.pone.0084468 .
  5. Jump up ↑ S. Kuriyama, T. Shimazu, K. Ohmori, N. Kikuchi, N. Nakaya, Y. Nishino, Y. Tsubono, I. Tsuji: Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan : the Ohsaki study. In: JAMA: the journal of the American Medical Association. Volume 296, Number 10, September 2006, pp. 1255-1265, doi: 10.1001 / jama.296.10.1255 . PMID 16968850 .
  6. ↑ Hirofumi Tachibana, Kiyoshi Koga, Yoshinori Fujimura, Koji Yamada: A receptor for green tea polyphenol EGCG. In: Nature Structural & Molecular Biology. 11, 2004, pp. 380-381, doi: 10.1038 / nsmb743 .
  7. ↑ Joshua D. Lambert, Shengmin Sang, Chung S. Yang: Possible Controversy over Dietary Polyphenols: Benefits vs. Risks. In: Chemical Research in Toxicology. 20, 2007, pp. 583-585. doi: 10.1021 / tx7000515 .
  8. ↑ Food Phytochemicals for Cancer Prevention. In: ACS Symposium. 547 // 1994, pp. 68-75.
  9. ^ MP Cohen, K. Sharma, Y. Jin, E. Hud, VY Wu, J. Tomaszewski, FN Ziyadeh: Prevention of diabetic nephropathy in db / db mice with glycated albumin antagonists. A novel treatment strategy. In: J. Clin. Invest. 95/1995, pp. 2338-2345.
  10. ↑ Green tea and rooibos tea in the case of kidney disease caused by diabetes. on: openpr.de accessed on November 26, 2007.
  11. ↑ Green tea reduces plaque formation in Huntington's disease - first results in model organisms ( Memento from January 5, 2007 in the Internet Archive ) Press release of the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch from September 8, 2006.
  12. ↑ D. Ehrnhoefer et al .: Green tea (-) - epigallocatechin-gallate modulates early events in huntingtin misfolding and reduces toxicity in Huntington's disease models. In: Journal Human Molecular Genetics. 15/2006, pp. 2743-2751.
  13. ↑ English-language article in EurekAlert
  14. ↑ Dagmar E Ehrnhoefer, Jan Bieschke, Annett Boeddrich, Martin Herbst, Laura Masino, Rudi Lurz, Sabine Engemann, Annalisa Pastore, Erich E Wanker: EGCG redirects amyloidogenic polypeptides into unstructured, off-pathway oligomers. In: Nature structural & molecular biology. 15, 2008, pp. 558-566. doi: 10.1038 / nsmb.1437 .
  15. ^ O. Aktas, T. Prozorovski, A. Smorodchenko, NE Savaskan, R. Lauster, PM Kloetzel, C. Infante-Duarte, S. Brocke, F. Zipp: Green tea epigallocatechin-3-gallate mediates T cellular NF-kappa B inhibition and exerts neuroprotection in autoimmune encephalomyelitis . In: J Immunol . November 2004, PMID 15494532 .
  16. ↑ Does green tea slow down inflammatory processes in the central nervous system? ( Memento of the original from April 4, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. from dmsg.de - accessed on April 5, 2011.  @1@ 2Template: Webachiv / IABot / www.dmsg.de
  17. ↑ organic-chemie.ch, Milk in tea inhibits the effects of catechin , published on January 11, 2007, accessed on July 29, 2009
  18. ^ RJ Green, AS Murphy, B. Schulz, BA Watkins, MG Ferruzzi: Common tea formulations modulate in vitro digestive recovery of green tea catechins. In: Molecular nutrition & food research. Volume 51, number 9, September 2007, pp. 1152-1162, doi: 10.1002 / mnfr.200700086 . PMID 17688297 .
  19. ↑ Sandra Ciesek, T. Hahn, CC Colpitts, LM Shang, M. Friesland: The green tea polyphenol epigallocatechin-3-gallate (EGCG) Inhibits Hepatitis C virus (HCV) entry. In: Hepatology . August 11, 2011 doi: 10.1002 / hep.24610 . PMID 21837753 .
  20. ↑ S. Misaka, J. Yatabe, F. Müller, K. Takano, K. Kawabe, H. Glaeser, MS Yatabe, S. Onoue, JP Werba, H. Watanabe, S. Yamada, MF Fromm, J. Kimura: Green tea ingestion greatly reduces plasma concentrations of nadolol in healthy subjects. In: Clinical Pharmacology & Therapeutics . 2014, pp. 432-438. doi: 10.1038 / clpt.2013.241 .
  21. ↑ This is how the tea hour succeeds. In: Stiftung Warentest . August 28, 2019, accessed September 11, 2019 .
  22. ↑ [1] on keiko.de, accessed on July 8, 2019.
  23. ↑ FAQ: The most common questions about tea and TeeGschwendner - Can I brew green tea several times, and if so, how often? at teegeschwendner.de, accessed on October 26, 2016.