Fermentation Process of Black Tea Manufacturing

Here comes the next processing step of black tea processing. Fermentation or the oxidation is the step of black tea manufacturing that will responsible for the colour of the black tea. During this oxidation process, rolled dhool is expose to the atmospheric oxygen. This process is started soon after damaging the leaf during the rolling process. Polyphenols in the tea leaf will mix with the poly phenol oxidase enzyme and starts to oxidise.

Derived dhools from the drying process will spread on the fermentation bed with a desired thickness. There are some important parameters to be controlled in this fermentation process. Most important one is the temperature of dhool. Optimum temperature for this reaction is 25 – 30 0C. This range of temperature will facilitate the reaction in controlled level. The next important thing is the thickness of dhool layer. To control the temperature in optimum level, dhool should be spread in 25 – 75 mm in thickness. The other one is the controlled room temperature. Humidifiers can be used in fermentation rooms to control the room temperature by controlling the humidity too. In this process hygrometric difference should be less than 2C.

When the process continues in correct manner rolled tea leaves change the colour in to coppery appearance. Not only the colour but also the aroma changes too. When fermentation continues in proper manner, dhools will have a pleasant fruity smell itself together with the coppery colour. Total time desired for the fermentation to complete will be calculated starting with the rolling. The time will be differ depending on the different grade according to the particle size. Tender shoots show the best appearance in fermentation than the over mature shoots. After the fermentation process is complete fermented dhools will dry in next step.

Since it desired the appearance and the liquor characteristics of the tea, fermentation is a critical point in tea manufacturing. It takes more experience to control this process in a desirable manner to obtain a best end product. Let us meet with drying process with next article.

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