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Chinese Black Tea Manufacturing Process

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)

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