ISHS Acta Horticulturae 218: XII African Symposium on Horticultural Crops
COMPARATIVE METHODS OF OPTIMISING FERMENTATION TIME IN BLACK TEA PROCESSING |
| Authors: | Philip O. Owuor, Stuart G. Reeves |
| Abstract:
Theaflavins (TF) and thearubigins (TR) are known chemical parameters of quality in black tea, and use of In-line theaflavins (ILTF) analysis method has been suggested as a method of optimising fermentation time. Data generated in experiments to optimise fermentation time by ILTF, measurement of TF in made tea (TFMT) and tasters' evaluation of made teas were subjected to statistical analysis. All the methods showed a quadratio relationship with fermentation time which was highly statistically significant (P = 0.001). Optimum fermentation times calculated from the generated equations showed that ILTF analysis method occurred ahead by 16 to 78 minutes compared to taster D's valuations, 39 to 60 minutes to taster E's and 8 to 82 minutes to the TFMT method. The average lag times between ILTF and the above methods were 31.2, 43.6 and 31.2 minutes, respectively. The difference between optimising fermentation time by the TFMT method and taster D was very small, while that of TFMT and taster E was wider. Taster D preferred teas which were brisker, brighter and lighter in body, while taster E preferred thicker and more coloury teas. The linear relationships between the different methods of optimising fermentation have high correlation coefficients. Tasters and TFMT methods of analysis were found to have the best relationship. In the absence of a taster, therefore, TFMT should be the method of choice in determining fermentation time. | |
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