#Raw Materials
Green tea is made from the top two leaves and buds of a shrub, Camellia sinensis, Theaceae, and the order Thales. This order consists of 40 genera of trees or shrubs with evergreen leaves, flowers with five sepal or leaf-like structures, and petals. The genus Camellia consists of 80 species of East Asian evergreen shrubs and trees. Besides the leaves, other ingredients may be added to create unique scents or flavors during the drying process, such as jasmine, flowers, or fruits.
The tea plant originates in an area between India and China. There are three main varieties of this plant—China, Assam, and Cambodia—and several hybrids in between. The China variety grows as high as 9 ft (2.7 m) and has at least 100 years of economic life. The Assam variety is a tree that grows as high as 60 ft (18.3 m), with an economic life of 40 years dependent upon regular pruning and plucking. The 16 ft (4.9 m) great Cambodia variety is naturally crossed with other types.
#The Manufacturing Process
Cultivation and harvesting
- 1 A suitable climate for cultivation has a minimum annual rainfall of 45-50 in (114.3-127 cm). Tea soils must be acidic since tea plants will not grow in alkaline soils. A desirable pH value is 5.8-5.4 or less. Tea can be cultivated up to 7,218.2 ft (2,200 m) above sea level and grow between the equator and the forty-fifth latitude. The plants are reproduced through tile-laying or through seeds from trees that have grown freely.
- 2 A crop of 1,500 lb (681 kg) of tea per acre requires up to two workers per acre to pluck the tea shoots by hand and maintain the field. The tea plant is generally plucked every five to 10 days, depending on where it grows. The length of time needed for the plucked shoot to redevelop a new shoot ready for plucking varies
- According to the plucking system and the climatic conditions. Intervals of between 70-90 days are standard.
- 3 In Japan, tea harvesting begins around the end of April, with the leaves picked by hand or machine. A bud and several leaves are selected from each plant. The first crop is harvested in April and May, the second crop in June, the third crop in July, and the final crop in September. For gyokuro or matcha tea, the plants are shaded for two weeks after the first bud comes out in spring before picking. The leaves are then shipped to the factory for processing. Since not all can be processed at once, the leaves are stored in a large bin kept at the proper temperature by blowing cool air into the bottom.
Drying
- 4 After the tea leaves are plucked, they must be dried to prevent fermentation, which stops any enzyme activity that causes oxidation. In China, green teas are often pan-fired in large woks, over a flame, or using an electric wok. The tea leaves must be stirred constantly for even drying. Withering is also used, spreading the tea leaves on racks of bamboo or woven straw to dry in the sun or use warm air. Again, the leaves must be moved around to ensure uniform drying.
- 5 In Japan, steaming is usually used. Before the steaming process begins, the tea leaves are sorted and cleaned. The steaming time determines the type of tea that is produced. Sencha tea is typically steamed for 30-90 seconds. A different kind of sencha called fukamushi is simmered for 90-150 seconds to have a flaky, light yellowish green tea. Steaming is conducted in a bamboo tray over water or by a revolving or belt-conveyor type machine. After mechanical steaming, the leaves go into a cooling apparatus that blows the water from the leaves.
Shaping
- 6 In most countries, rolling or shaping green tea leaves is done by machinery. In China, high-end leaves are hand-rolled into various shapes, including curly, twisted, pointed, round, and more. Rolling the tea creates a distinctive look and regulates the release of natural substances and flavor when it is steeped in the cup.
- 7 In Japan, several rolling and drying steps take place. A particular machine is used to accomplish the first rolling and drying steps simultaneously and takes about 48 minutes. The tea leaves are dried to improve their strength to be pressed during the subsequent drying process. Moisture from both the surface and from the inside of the tea leaves is removed using this machine.
- 8 This machine consists of a spindle with finger-shaped extensions that stir the leaves while heated air (at 93.2-96.8° F [34-36° C]) is blown into the machine. Though the computer automatically controls the rolling temperature, it is still essential for the operator to touch the tea by hand to make sure it feels right.
- 9 Since the moisture level still varies for different parts of a leaf or from one leaf to another at the end of the first step, another rolling process is to distribute the remaining moisture in the leaves uniformly. This process rolls the leaves by pressing under a rotating disk to bring the water from the center of the leaves to the surface. The process is conducted at room temperature for 24 minutes.
- 10 Next, the leaves go to another rolling/drying machine, which uses a spinning pedal inside of a revolving drum to convert the leaves into a round shape. This process takes about 40 minutes. It is essential to take out the leaves at the same moisture level every time.
- 11 The tea leaves are removed from the previous machine, separated into small portions, and placed in pots. They are gradually rolled into tiny round or needle shapes using a weight. This step takes 40 minutes and removes most of the moisture. The whole process thus far takes about three hours compared to hand-rolling and heating, which can take up to 10 hours.
Final drying
- 12 In Japan, green tea must be dried for about 30 minutes after the final rolling step for storage. The tea is spread on a caterpillar-type device and dried slowly to about 5% moisture content or less. At this stage, the half-processed tea, called Paracha, is shipped to tea merchants or wholesalers for final processing. Aracha is not uniform in size and still contains stems and dust.
Post-processing
- 13 After the tea is shipped to the wholesalers in Japan, it undergoes several other steps to produce the final product. A unique machine grades and cuts the tea by particle size, shape, and cleanliness, depending on the absolute qualities desired. The machine uses mechanical sieves or sifters fitted with meshes of appropriate size and cutting devices to achieve a quality tea. Another drying step is to produce the aromatic flavor, then blend per customer's specifications, pack, and finally ship to retail shops. In other countries, similar sorting, weighing, and packaging steps occur after the shaping process.
#Quality Control
The quality of green tea depends first on using good tea leaves. The natural quality of the leaf, including color and aroma, must then be preserved during the manufacturing process to produce an excellent green tea. In Japan, this involves controlling the temperature to 93.2-96.8° F (34-36° C) during rolling, drying, and storage. Since tea leaves can generate their heat, cool air is blown into the bottom of the container to keep the leaves at the proper temperature during storage.
The Japanese government also subjects all exported tea to a strict inspection. Standard samples, which are established at the beginning of the tea season each year, are used to compare various properties of the finished product with the models. Leaves, stems, moisture, content, flavor, taste, and color are all rigidly examined. There is also a rigorous chemical analysis to determine tannin, caffeine, vitamin, and mineral contents. Tea is exported only after passing these tests.
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