Manufacturing Process of China tea---Green tea & Black tea

Although different  teas may be produced by different processing techniques,the general  tea processing is achieved as follows: fresh tea leaves plucked →

Green tea: Fixed（or de-enzymed） -Rolled -Dried steamed or pan-fried to inactivate oxidase) 

Yellow tea: Fixed -Rolled -Yellowed 闷黄-Dried(piled and smothered to auto-oxidize)
Dark tea: Fixed -Rolled -Pile渥堆 -fermented -Dried(oxidized by the oxidases of resident microbes)
White tea: Withered -Air dried or baked Re-fired(with more fine hairs/flosses)
Oolong tea: Withered -Bruised (shaken)Partially fermented -Fixed -Rolled -Dried
Black tea:Fresh tea leaves -Withered -Rolled- Fully fermented- Dried(orthodox rolling传统造型 or CTC红碎茶)

Green tea manufacturing

It is worthy to note that different kinds of green tea have different requirementsof plucked young tea shoots. The common young tea shoots required are one budand two or three leaves,一芽二三叶 while those for famous high-quality green tea are usuallyone bud and one leaf一芽一叶, even just one bud一芽.In Japan, some high-quality green teassuch as gyokuro and matcha are produced from the fresh tea leaves grown under90% shading遮荫 for 2 weeks and 40–50% shading for 1–2 weeks before being plucked,respectively. The quality of fresh tea leaves plays a key role in the characteristics ofgreen tea.

In the harvesting season, the tender tea shoots are plucked by hand or a mechanicaltea plucker and delivered to tea factories immediately. In order to prevent fermentation(the oxidation of catechins儿茶素) and formation of the characteristic “greenleaf, green liquor of green tea, the leaves are immediately fixed to inactivate theendogenous enzymes by steam or heat with pan frying, roasting, or baking. However,on the heavy harvesting days, the leaves are thinly spread out indoors in a shallow basket in the racks, or some ventilating通风的 beds like bamboo mesh mats草席，trays, troughs,槽spreading machines, and wait for fixation. The waiting time should be as short as  possible to avoid oxidation, which turns the green leaf and stem to red. The tea fixationapparatus include a tea steaming machine, wood-fired pan, electrical pan, rotaryheated drum, microwave, and far infrared. When fixed leaves become soft and flaccid,they are conveyed to be rolled, and then the rolled tea masses are loosened解蒂 bya roll breaker or ball breaker and moderately cooled. Subsequently, the leaves arefired (dried) by charcoal-fired baking baskets, electrical heaters, coal heaters, liquidpetroleum gas heaters, or natural gas heaters. The moisture content of the final product (crude tea) should be less than 6%.

According to the fixation ways, green tea is subdivided into steamed green tea 蒸青、pan-dried green tea炒青、roast-diried  green tea烘青and sun-dried green tea晒青.  Steamed green  tea is mainly produced and consumed in Japan,  while pan-dried green tea is mainly produced in China and exported to the world.Crude green teas are usually refined by the wholesale tea dealers. The refiningprocess generally includes sifting筛分, cutting切削, grading分类, refiring复火, polishing磨锅抛光, blending拼配, and  packing包装. Through refining, the stalks, dust, and impurities are removed. The final tea  has a uniform size and standardized appearance, such as Chunmee珍眉, Sowmee秀眉, and Gunpowder珠茶Chunmee and Sowmee are renowned for their curve shape, like the humaneyebrow, while Gunpowder is featured with tiny, tight, round balls like gunpowder.

Black Tea Manufacturing

Unlike the enzyme inactivation process of green tea, the enzyme activities are completelyutilized in black tea processing to form the pigments (theaflavin茶黄素 and thearubigin茶红素).Although the processing methods vary with the producing regions, the generalblack tea processing is: fresh tea leaves plucked采摘 → withered萎调 → rolled 揉捻→ fermented发酵（actually it's oxidation). Among those four steps, the fermentation process is crucial to the quality of the final black tea product, which is predominated with the oxidation of catechinsand production of oxidation reaction products.The typical plucked tea flush for black tea processing is one bud and two leaves.

On arrival at the factory, they are spread out on large trays, racks or mats, troughs,or a machine and are left to wither by natural air current under sunshine or indoorcontrolled ventilation/aeration通风有氧 with the aid of warm-air fans. The moisture in theleaves evaporates and the leaves become limp and flaccid. Subsequently, the leavesare processed by orthodox roller or rotorvane, or CTC (crushing, tearing, and curling)machine, or LTP (Lawrie tea processor) machine. Most of the black tea in India,Sri Lanka, and Kenya is manufactured using the CTC process, while that in Chinais processed principally by traditional orthodox rollers. The objective of the rollingis to break the leaf cells and release the oxidases, including polyphenol oxidase andperoxidase多酚氧化酶和过氧化酶, and initiate the process of catechin oxidation with oxygen in the air.Importantly, CTC can be used to handle efficiently large volumes of tea leaves, rapidlyrupturing withered tea leaves to small particles and forcing out most of cell sap,which leads to sufficient fermentation充分氧化.After rolling, the broken tea leaves are transferred to the fermentation room andlaid out thinly on trays, in troughs, or on the floor at a little warm (25–35°C), highhumidity (>95%) atmosphere for fermentation. The fermentation time ranges froma half hour to 3 hours, depending on the variety of tea plants, the age of tea leaves,the particle size of broken tea leaves, and the fermentation condition. Among thesefactors, the rupturing technique plays a key role. Generally, tea leaves macerated使浸软by CTC machine need a short time, from 30–60 minutes, while tea leaves rupturedby orthodox roller take a long time, from 2–3 hours. In this process, the broken tealeaves set to fully oxidize, which starts during rolling. Due to the oxidation, greenleaves gently turn to golden russet黄褐色 color and the greenish leaf note turns to a freshor floral aroma.As the optimum 最佳效果的fermentation is achieved, the leaf mass is dried or fired to inactivatethe enzymes and halt the fermentation. Continuous driers are usually used,in which hot air is generated by electrical heater or coal furnace. In this process,the leaf turns dark brown or black, the aroma changes to floral, and the moisture isreduced to less than 6%.The crude black teas produced in the world are mainly congou (Gongfu) blacktea and CTC black tea, which are processed by orthodox rolling and CTC machine,respectively.

Apart from those two, there is still a minor productivity Souchong black tea produced in the Wuyi (Bohea) mountain area in China. It is said thatsouchong black tea was created in the middle of the fifteenth century, and lapsangsouchong (Zhengshan Xiaozhong正山小种) is known to be the origin of black tea. The processingof lapsang souchong is similar to that of congou black tea, except that thefermented dhool (refers to the tea leaf during fermentation, noted for its copperycolor) is fired at 200°C for several minutes and rerolled before final drying. In addition,souchong black tea can be further processed by the absorbance of the scentsreleased from the burning pine branches to smoked souchong black tea, which isknown for its smoked flavor.

Similar to crude green tea refining, crude black teas are refined through sifting,cutting, grading, blending, refiring, and packing. Through the refining, the stalks,fibers, and impurities in crude tea are removed. The fine teas are graded to fourvarieties as whole leaf grades, brokens, fannings, and dusts. Moreover, each varietyis subdivided into several categories as summarized in the following list. 

Whole leaf grade: flowery orange pekoe白毫 (FOP), golden flowery orange pekoe(GFOP), tippy golden flowery orange pekoe (TGFOP), finest tippy goldenflowery orange pekoe (FTGFOP), special finest tippy golden floweryorange pekoe (SFTGFOP), orange pekoe (OP), pekoe (P), flowery pekoe(FP), pekoe souchong (PS), souchong (S)

Brokens: flowery broken orange pekoe (FBOP), golden flowery broken orangepekoe (GFBOP), golden broken orange pekoe (GBOP), tippy golden brokenorange pekoe (TGBOP), tippy golden flowery broken orange pekoe(TGFBOP), broken orange pekoe (BOP), broken pekoe (BP), broken pekoesouchong (BPS)

Fannings:orange fannings (OF), broken orange pekoe fannings (BOPF), pekoefannings (PF), broken mixed fannings (BMF)

Dusts: pekoe dust (PD), red dust (RD), fine dust (FD), golden dust (GD), superred dust (SRD), super fine dust (SFD)