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Green Tea


About Green Tea



Introduction

Green tea is almost synonymous with wellbeing; of all the brew-worthy descendants of the Camellia sinensis plant, green tea is the one most associated with salubriousness. There has been a great deal of interest, both public and scientific, in the reputed medicinal properties of the drink and many studies have probed these claims. For more information, see the Kettle Shed’s full green tea guide.

Most prevalent in Japan and China (from whence it first hailed), the consumption of green tea is increasing in the West as word spreads of its rich history and traditions, bright taste and potential health benefits. Whilst many westerners report an inferior flavour in comparison to black or oolong teas, green tea compensates with its delicacy and fortification of fettle. Rather like a 25-year-old single malt scotch, it is an acquired taste, but one infinitely worth acquiring.

Taste

The flavours of individual green teas are so diverse that defining the taste of green tea in general is rather tricky. Nevertheless, it is fair to say that; overall, green tea possesses a sharper, brighter flavour than other varieties, individual flavours varying from the velvety sweetness of Matcha, to the astringent zest of Gunpowder.

As it is made from the least oxidised leaves (and is therefore closer to its natural, unrefined form), some drinkers report a ‘grassy’ aftertaste. If the heady herbal essence disagrees with your palette there are alternative black and yellow teas with similar properties but more a refined taste. Moreover, you can add certain ingredients to the brew to tailor the taste to your liking; popular additions include honey, sugar, syrup and milk.

Health

Green tea has provoked much speculation concerning the potential health benefits of its consumption. Some of these claims are rooted in rumour and folklore, whilst other claims have been discovered, supported or disproved by scientific study. Before exploring these assertions, it is important to note that research into the health benefits of tea is still in its infancy and there is still much to learn.

The Kissa Yojoki (or ‘Book of Tea’), penned by the Zen priest Eisai in 1191AD, provided one of the earliest essays into the effects of green tea, these included help alleviating tiredness, drunkenness, blotchiness and indigestion. Eisai also asserted that green tea could cure Beriberi disease, enhance one’s mental and urinary faculties and even submits the outlandish idea that it can quench thirst.

More recent, and perhaps empirical, research has been conducted to determine what effects green tea has on the body. Steel yourself, here comes the science!

In Edinburgh, research performed at the Queen Margaret University indicated that green tea consumption reduced certain cardiovascular risk factors, such as cholesterol and blood pressure.

Researchers at the University of Birmingham found that ingesting green tea extract increased beta (fat) oxidation, the process by which bodily fats are broken down to provide energy.

A study at the University of Hong Kong seemed to indicate that the catechins in green tea were absorbed optically, alleviating stress on the eye for almost a day. This means that the ingestion of those catechins could help to prevent eye conditions such as glaucoma. However this has not been tested on humans yet.

Green tea does not contain as much caffeine as black tea, nor does it possess the theaflavin antioxidant. Instead, green tea boasts the highest concentration of the catechin affectionately known as epigallocatechin gallate (or EGCG), which is the focus of much scientific attention.

A study at the Slovenian National Institute of Chemistry found that EGCG may contribute to oral hygiene.

Another study, conducted on mice with Alzheimer’s and Parkinson’s disease at the Institute of Technology in Israel, showed that EGCG not only helped prevent the loss of brain cells, it actually restored some damaged neurons. Further research is currently in progress.

Testing at the Linus Pauling Institute in American indicated that EGCG could fortify the immune system and increase the numbers of T cells in the body.

Other research suggests that ample ingestion of green tea might reduce LDL cholesterol (although e provided differingresults), lessen stress and depression, decrease the chances of developing rheumatoid arthritis and certain types of cancer (such as breast and prostate cancer). However, much of this research is yet to be completely confirmed (and some of the research was carried out on other species such as mice).

Lastly, the properties of green tea are also known to affect certain types of medication. For example, the polythenols in green tea can bind and neutralize bortezomib (a drug used to counter cancer), rendering it ineffective. The vitamin K in the tea can counteract the blood-thinning drug, warfarin. In fact, green tea itself possesses some anticoagulant properties and is not recommended for pregnant or breastfeeding ladies. You can click here for a more detailed list of effects compiled by the University of Maryland Medical Center.

For further information concerning the effects of green tea on medication and physiology, there is no substitute for a doctor.

Origin

Green tea originated in China and, as evidenced by various allusions to the brew in early Chinese documents, is thought to have been quenching our thirst for around 5000 years.

There are differing legends surrounding the discovery of tea as we know it. In one story, a Chinese man called Shien Non Shei became thirsty whilst hiking and twisted a leaf which left traces of fluid on his fingers. He tasted the fluid and postulated that it could assuage thirst if brewed, and perhaps even possess medicinal qualities.

Our favourite legend at the Kettle Shed is the tale of Emperor Shen Nung, who, on discovering that a leaf had accidentally drifted into his bowl of warm water, decided that the water’s flavour and aroma had been significantly improved. Considering the last 5000 years, he may have had a point.

Japanese variants of the tea blossomed into existence after green tea became popular there in the 9th century. In addition to cultivating Bancha, Matcha and a host of other fantastic green teas, Japan enriched the sub-culture surrounding the beverage with customs such as the Chado tea ceremony.

The process by which green tea is made involves less tampering with the leaves than the processes that produce other teas (such as black or oolongs) from the Camellia sinensis plant. To make green tea the leaves are dried immediately after harvesting, without the intermediary oxidisation (or fermentation) phase which defines its counterparts.

The unadulterated leaves retain the largest number of health fortifying substances, although the chemicals produced by oxidisation in other types of tea are sometimes more apt to particular complaints. For example, the antioxidant ‘theaflavin’ is produced by oxidisation and is found in black tea.

Growing the plants in the sun or the shade makes a difference to their taste and chemical content. Tea grown in the shade tastes sweeter because it contains fewer catechins, which are partly responsible for the astringency of the brew. Moreover, shade-grown teas contain extra caffeine and theanine (a stress-reducing amino acid).

Brewing Tips

  • Don’t boil the water. Different green teas infuse better in slightly different water temperatures, generally between 70°C (160°F) and 85°C (185°F).
  • If your last cup of tea was too bitter, try steeping at a slightly lower temperature or for less time.
  • Use between 1 and 2 grams of leaves per 100ml of water, depending on the inherent strength of the tea and personal preference.
  • Unlike black teas (wherein the darker the brew, the stronger the infusion), a green tea infusion cannot be assessed by colour. So judge it by taste.
  • Cover your teapot or gaiwan with a lid to trap the steam.