The fresh green plucked leaves undergo various manufacturing process as soon as they are brought to the factory.
The tea leaves are withered by spreading them in a trough where moisture from the leaves are removed by drying them naturally or (depending on the flush and tea made) by drying them artificially with dryers where two third moisture of the leaves are removed.
After weighing the withered leaves, they are then rolled for 20 to 60 minutes in cast-iron rollers for mechanical processing.
The purpose of rolling is to twist the withered leaves to obtain
the desired grade then to rupture the cells to let the enzymes to act upon the leaves which also speeds up fermentation process towards achieving the desired flavour and colour. The duration depends on the quality of leaves and seasonal timings.
As the name suggests, the rolled leaves are sorted through sifters to sort the unrolled leaves for a second roll.
After rolling comes the process of fermentation, the most critical part of tea manufacturing process which is considered the art of tea manufacture, where, the twisted and ruptured leaves are spread in a cool, humid room in very thin layers for any where between one hour to four hours, the duration of which also depends on various climatic conditions.
In this process the flavour from the ruptured leaves are extracted releasing unique flavour, aroma and colour characteristic of Darjeeling tea.
After fermentation (Oxidation) the leaves are sent for drying.
Drying is a process where the the goal is to stop the “enzymatic mellowing”. The leaves are dryed and the moisture content is reduced by 2 to 3 percent at a temperature between110 ºC
to 115 ºC for less than half an hour.
The dried leaves are then sorted into grades with the help of sifters.
Shifters have meshes with different size which help in tea grading depending on leaf size.
This is not an ordinary process of storing but done carefully to reduce the moisture through a process called Gapping, where special dryers are used to dehumidify the leaves before finally being packed.