What is green tea?
It's a beverage with a long and noble history throughout China and a significant number of other Asian countries such as Japan, but surprisingly few people actually know what the difference is between green tea and ordinary tea, other than the color! Most, however, could tell you that green tea is well known for its health benefits, and that it has a fresher flavor than black tea. But what is green tea?
If Chinese legend is to be believed, green tea was “discovered” by an rich emperor. Making his way through forest ground, he was setting up camp for the night and boiling some water to drink. When he returned to his kettle, he found that a gust of wind had blown some leaves from a nearby tree into the boiling water. Annoyed, but tired and unwilling to go in search of more water, he decided to drink it anyway, even though the leaves meant that it now had an unusual green tinge. And lo and behold, he discovered that it tasted better than any water ever had before! The industrious emperor gathered up some more leaves from the tree and took them home with him... and so tea was invented.
Whether this is just a nice little legend or a true story, it does help to illustrate the difference between green tea and ordinary tea. Both kinds are made from the leaves of the same plant: the Camellia Sinensis, or “tea plant”. The difference is in how the leaves are treated after being picked.
Black tea goes through a 4-step process. First, the leaves are “withered”. This reduces the moisture in the leaves by about 70%, although the percentage varies somewhat in different tea-producing regions. Once the tea has been withered (this usually takes from 12 to 17 hours), the leaves are quite limp – ideal for rolling, which is the next step. Tea leaves are machine-rolled into the wiry, twisted shape that you'd recognize, and in the process they are forced to break open. This kick-starts the third step: oxidization. The rolled, cracked leaves are laid out so that the enzymes in each leaf are exposed to the surrounding air. As they oxidize, the leaves change color, going from green to increasingly dark shades of brown. The eventual strength and flavor of the tea depends on how far along this process the leaves are allowed to go. Oxidization can be stopped at any point by drying the leaves (passing them through hot air dryers).
Green tea leaves, on the other hand, are much closer to the original state of the freshly picked leaves. Occasionally they go through the initial “withering” stage, but it's much more common for this part to be completely omitted. The freshly-picked leaves are instead pan fired or steamed before being rolled. This means that they won't break open in the rolling process, so no oxidization will occur – this is the key difference between green tea and black tea. The enzymes in the leaves are not exposed to the surrounding air, and so the tea remains green, and the flavor unchanged by chemical reactions. The leaves are then dried, sorted and packed just like black tea.
As a result, green tea has a much fresher, delicate flavor. It doesn't keep fresh for as long as ordinary tea, but its health benefits and unique flavors make it an increasingly popular alternative.
Useful Links:
http://en.wikipedia.org/wiki/Green_tea
http://www.wisegeek.com/what-is-green-tea.htm
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