The Influence of the Manufacturing Process on the Qualities of Black Tea (Part 3)

The Influence of Temperature during Rolling on the Qualities of Black Tea

Abstract

The influences of the temperature of the rolling room on the qualities of black tea were investigated. And also the chemical changes in the tea leaves were researched.
1. It was recognized that the oxidative activity for polyphenol fell down in the leaves rolled at 45°C. And that in the leaves rolled at a temperature between 15°C and 40°C was maintained at a constant level.
Therefore, the oxidized products of polyphenols in the leaves rolled at a temperature between 15°C and 40°C were formed normally with the lapse of the fermentation period. But the formation of the oxidized products of polyphenols in the leaves rolled at 45°C was depressed.
2. The color of infusion of black teas rolled at a temperature between 15°C and 35°C was bright and rich, but that of tea rolled at 45°C was pale.
3. The optimum fermentation periods were 180 min., 120 min., and 60 to 90 min., when rolled at a temperature of 15°C or 20°C, 25°C, and 30°C or 35°C, respectivelly. And the leaves rolled at 45°C did not reach enough fermentation after 120 min.
4. The black tea made by rolling at a temperature between 15°C and 35°C had. a good aroma and briskness in taste. But the tissue of the leaves rolled at 15°C became frasile, and the leaves were broken to small fragments during rolling, therefore, the style of made tea was degraded.
The qualities of black tea made by rolling at 45°C were inferior to these of teas rolled at a temperature lower than 45°C.
From these results, it was thought that the optimum rolling temperature existed between 20°C and 35°C.