Rolling Process in Black Tea Manufacturing

Let us continue to another black tea processing step this time. Last time we have got the knowledge on withering process. Next step in black tea manufacturing is rolling of the withered green leaf. 

Rolling is very important since it is the first most step that will facilitate the oxidation process in tea leaves. Fresh tea leaf content the polyphenol and polyphenol oxidase enzymes in separate cells without mixing each other. To facilitate the oxidation process which is responsible for the specific black colour and liquor colour, these two compounds should be mixed. In the rolling process, cell walls of the tea leaves will be ruptured and polyphenol and polyphenol oxidation enzymes will mix together. Then the natural oxidation will be started. This is why rolling plays a critical role in black tea manufacturing.

There are two methods of rolling as mechanical rolling and manual rolling. For mechanical rolling method rolling machines are used. These machines are made with roller table with battens where tea is placed for rolling purpose. Rolling jacket is the other major part which is located at the top of the table attached to a shaft which facilitate circular motion. These machines are mainly working with electrical supply. 

Pressure can be applied as it needed in rolling process. Roller tables can be charged manually or mechanically. Then the machine will start the rolling with a given speed and a pressure. Most of the times in large scale productions mechanical rolling is very much suitable. 

When it comes to the manual rolling, it is the very traditional and primary method which is still used in small scale manufacturing of black tea. most of the times handmade tea producers are using this method. In manual rolling withered tea leaves will be put in a cane or bamboo strapped flat baskets. Then tea leaves will be rolled by the hands pressing on the flat surface. Leaves will rupture and curled by the rough straps of the basket. When leaf particles come to the desired appearance rolling can be stopped and take them to the next step. This manual method is still used since it gives a unique colour, flavor and aroma with desired particle appearance in hand made tea. 

At the end of the rolling process withered leaves become curled, coppery colour particles with a fruity aroma. To obtain the desired characteristic rolling time is one of the very important fact. Because of that rolling programs are used in large scale production of black tea. in this rolling programs, roller charging intervals with a specific time will be mentioned. Following this program will avoid excessive rolling which leads to over fermented dark colour tea with dull appearance. At the end of the rolling of a batch rolled leaves will call as “Dhool”. The dhool will discharge by the discharge door in the roller table. These dhools will take in to the roll breaking process and large paticles will undergo rolling process again which is called as second dhool. 

Hope this article provided a rough idea on the rolling process until we meet with the next article about roll breaking process.

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