Tea Cultivation and Processing
The tea plant or camellia senensis is an evergreen bush which grows primarily in tropical and sub-tropical regions. The various forms of the tea leaf known to tea drinkers around the world are the product of centuries of careful cultivation and processing. Although the tea plant remains essentially the same from one growing region to another, the soil characteristics, climate, altitude and processing methods yield a diverse spectrum of flavors. It also tolerates a wide range of soil conditions and seasonal fluctuations. Recent agricultural research by tea growers has greatly improved crop yields and the overall quality of the tea produced.
The tea plant in its wild state will grow to heights exceeding 18 to 20 feet. The Chinese, in fact, have discovered numerous wild tea plants considerably taller, notably one in the Yunnan Province over one hundred feet high which has been growing for seventeen hundred years! But with the exception of plants raised for their seed rather than their leaf, tea bushes are usually pruned to about 3 feet tall, and are flattened across the top. This flat profile allows the harvesting of new growth from the plant as it comes up, assuring the most flavorful product. Only half of the total leaf production from the plant is ever harvested, allowing the plant to survive to produce new growth year after year rather than go to seed.
The harvesting of the leaves is called plucking, and categorized as either "fine" or "coarse" according to whether two leaves and a leaf bud are plucked, or three or more leaves are plucked. In fine plucking, only the two topmost leaves and the leaf bud are picked since these portions of the plant yield the greatest flavor and aroma. A rare white tea called Silver Needles consists of leaf buds. A type of unfermented tea, this tea is considered one of the most delicate of Chinese teas, and represents an extreme form of "fine plucking." Coarse plucking generally yields a lesser product as it included leaves from earlier growth, but it is possible for coarse plucked tea from an exceptional plant to actually be better than fine plucked tea from an inferior plant.
Once the leaf is picked, it immediately begins a complex biochemical process in which oxidation occurs. The interruption of this "fermentation" process at various stages is what gives rise to the three basic types of tea: green, white, oolong and black. Just as coffee is roasted to differing degrees from light to dark, various fermentation times produce different tea flavors.
Green tea leaves, shortly after being plucked from the tea bush, are steamed briefly to prevent the natural oxidation of the leaf. This "unfermented" leaf remains green in color, and while still soft, is rolled and then dried mechanically or in a pan over heat. This rolling and drying process arrests the fermentation of the enzymes in the leaf, and stabilizes it for storage and transport. White tea is similar to green tea, in that it's undergone very little processing and no fermentation. But there is a noticeable difference in taste. Most green teas have a distinctive "grassy" taste to them, but white tea does not. The flavor is more light and sweet.
The second type of tea - Oolong tea – is "semi-fermented," meaning the fermentation process is not allowed to go to completion as in the case of black or "fully-fermented" tea. Oolong teas are characteristically darker in the cup than green tea, and in leaf form are greenish-brown in color. Oolong teas retain some of the vegetative character of green teas, but because of the fermentation which has occurred, they also yield the fragrant, somewhat floral flavor for which they are famous.
Oolong tea begins, as green tea does, with the "withering" process. The leaves are spread out and allowed to wilt, losing much of their moisture in the process. Once fully withered, the leaves are then rolled by machines, bringing the flavorful tea juices to the surface. Unlike green tea, which at this point would be steamed to stop the oxidation process, the wet leaves for oolong teas are allowed to oxidize, turning the tea leaf a greenish brown color.
It is this "oxidation" process (frequently referred to as "fermentation") which ultimately is responsible for tea's distinctive flavor. Enzymes, polyphenols and pectins react with oxygen during this process, changing both the color and flavor of the tea. At just the right point, Oolong tea is dried either in the open air, or by fans and warm air to halt the oxidation process.
The third kind of tea, and the one most familiar to western tea drinkers, is black tea. As the name implies, this tea is darker both in its leaf and brewed forms. The pale amber of the Oolong leaf gives way to a deep reddish brown in black teas. Similarly, the brewed tea is robust and brown in color. Black teas are basically Oolongs which have been allowed to fully ferment. Where Oolongs are oxidized for several hours, black teas are allowed to ferment for a day more.
Oxidation is also responsible for the caffeine content in tea. Green tea has very small caffeine content. Oolongs somewhat more and fully fermented black teas contain the most - about 46 milligrams of caffeine per cup, or about 1/3 the caffeine content of a cup of coffee. Although pound for pound, tea contains more caffeine than coffee, but the amount used to make a cup of tea (by weight) is considerably less. Back to Top