Withering Process in Black Tea Manufacturing

After gathering knowledge about plucking process of fresh tea leaves, next comes to the manufacturing procedure of black tea. Very first step in manufacturing black tea is withering. Withering is a process which is mainly oriented in reducing moisture of fresh tea leaves into a desired level that can be ideal for the rolling process. In this process fresh tea leaves will spread on the special structure prepared for withering and let them comes to the desired moisture level.

There are two major methods in withering. They are called tat withering and trough withering. ‘Tat withering’ is an old fashion traditional method of withering. In this method tats or the trays that made from bamboo material or other kind of natural material is used. Selectively picked immature tea leaves are spread in these tats and let them dry in natural air. Most of the times this method is used in traditional Asian tea manufacturing in small scale. The other method ‘trough withering’ which involves a special structure called withering trough. This is made by woods with the width of 6 feet and height of 3.5 – 4 feet with a convenient length. Inside the trough there is a mesh attached to the wooden frame horizontally as a table to facilitate the spreading of fresh tea leaves. These troughs are provided an artificial hot air with a control flow rate with an air flow fan operated mechanically. This air flow is responsible on moisture reduction to a desired level.

In the withering process relative humidity plays a critical role. Since the ambient air moisture level effect on moisture removal or the reduction from green leaf control in relative humidity is very much needed in succeeding this process. This measurement is taking as the hygrometric difference. Ideal hygrometric difference for withering process is 3C between dry and wet bulb temperature. To control this hygrometric difference and maintain this relative humidity, withering areas are occupied with humidifiers. Considering the ideal time duration for withering it takes nearly 16 – 18 hours. When leaves comes to the desired withering level its colour and the aroma will be changed. This will helpful in identifying the desired withering level by an experience person.

Then these withered leaves go to the next step called rolling. In next article on this black tea processing series, we will read about rolling. Visit our blog frequently for completing your knowledge regarding the path to a quality cup of black tea.

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