Department of Chemical Engineering, Amirkabir University of Technology, P. O. Box 15875-4413, Tehran, I. R. IRAN
The optimum fermentation times of black tea manufactured by two systems of Orthodox and CTC (cut, tear & curl) were investigated by measuring the quality parameters of black tea, like: theaflavin, thearubigin, highly polymerized substances and total liquid colour during the fermentation stage. Optimum fermentation times from the beginning of fermentation were determined to be 60 min and 150 min for the fine and coarse tea of orthodox manufacturing, respectively. The optimum fermentation time of CTC tea process was 30 min. Most theaflavin content of Orthodox and CTC processes were 0.63 and 0.82 percent of the total dried solids of infusions, respectively. Total color of CTC manufacturing was 16% higher than Orthodox process.
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