BLACK TEA

Black tea is prepared from green tea. The tea plants used for making black tea are selected specifically for their flavor and aroma. The collection of the tea leaves for green or black tea will be the same, though the precise timing of harvest can vary. The tea leaves are picked by hand.

Harvesting tea leaves

Fresh tea leaves in the withering bins

The green tea is brought to a factory where several processing steps are carefully monitored. On arrival at the factory, the plucked leaf is weighed and assessed for quality before being put in withering bins attached to huge air vents. The moisture in the leaf evaporates in the warm air leaving the leaves flaccid. This process can take 10-16 hours, depending on the wetness of the leaf. Some factories will gently hasten the process with the aid of warm air fans.

The withered leaf is broken down by rolling the leaves, which ruptures the leaf cells to release enzymes; on contact with the air, the leaf contents are partly oxidized. Then the leaves are twisted or curled. Additionally, the rolled leaves can be processed by a machine: its sharp teeth cut the leaf then tear it to release the juices that contain the tea flavor, and intensifies the fermentation process.

Machine for cutting and tearing tea leaves

Cut tea leaves on the oxidizing trays

The broken leaf is laid out, either on trays or in troughs, in a cool, humid atmosphere for up to two hours to ferment, or more correctly, oxidize. The trays are gently turned every so often throughout the period until all the leaves turn a golden russet color and fermentation is complete. This is one of the most challenging stages of production. Thereafter, to stop fermentation, the leaf is exposed to hot air by passing it through a drier with perforated moving trays in a process known as "firing." As the leaf dries, it turns a black color. It is at this stage that the aroma changes from that of a pungent plant to the familiar earthy tea perfume. The black tea is ejected from the hot chamber into chests. After the fired leaf is cooled, it is sorted by sieves, which yield different tea grades. The larger leaf curls are the high grade material used for making loose-leaf packet tea, while the fine pieces are used for tea-bags; the powder is considered waste material (which can be processed as a source of isolated tea catechins, caffeine, or other components).