Optimization of Fermentation Time for Iranian Black Tea Production

Document Type: Research Article


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.  


Main Subjects

[1] Arzpeima, F.A., “History of tea and tea industry in Iran”, Tea Org. of Iran Pubs., 220, 65  (1999).

[2] Owuor, P. O. and Reeves S. G., Optimizing  fermentation time in Black Tea Manufacture, Food  Chemistry, 21, 195 (1986).

[3] Robertson, A., Effects of physical and chemical   conditions on the IN VITRO oxidation of tea leaf   catechins, Phytochemistry, 22 (4), 889 (1983).

[4] Haslam, E., Thoughts on thearubigins, Phyto-  chemistry, 64, 61 (2003).

[5] Owuor, P. O. and McDowell I., Changes in theaflavin composition and astringency during black tea  fermentation, Food Chemistry, 51, 251 (1994).

[6] Tufekci, M. and Guner, S., The determination of  optimum fermentation time in Turkish black tea  manufacture, Food Chemistry, 60, 53 (1997).

[7] Angayarkanni, J., Palaniswamy M., Murugesan, S. and Swaminathan, K., Improvement of tea leaves fermentation with Aspergillus spp. Pectinase, J. of Biosci. Bioeng.,  94 (4), 299 (2002).

[8] Willson, K. C. and Clifford, M. N., “Tea cultivation to consumption; the chemistry & biochemistry of black tea production”, Chapman & Hall, 555-601 (1992).

[9] Ravichandran, R. and Parthiban, R., The impact of mechanization of tea harvesting on the quality of south Indian CTC teas, Food Chemistry, 63 (1), 61 (1998).

[10] Obanda,  M., Owuor, P. O.,  Mang’oka,  R.  and Kavoi, M. M., Changes in thearubigin fractions and theaflavin levels due to variations in processing conditions and their influence on black tea brightness and total colour, Food Chemistry, 85, 163 (2004).

[11] Owuor, P. O. and Obanda, M., The changes in black tea quality due to variations of plucking standard and fermentation time, Food Chemistry, 61 (4), 435 (1998).

[12] Cloughley,  J.  B.,  The  Effect  of  Fermentation Temperature on the Quality Parameters and Price Evaluation of Central African Black Teas, J. Sci. Food Agric., 31, 911 (1980).

[13] Owuor, P. O., Obanda, M., Comparative responses in plain black tea quality parameters of different tea clones to fermentation temperature and duration, Food Chemistry, 72, 319-327 (2001).