Studies on the Color of Liquor of Black Tea (Part 1):On the Color Grading of Liquor of Black Tea with Electric Photometer

概要

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1. In order to establish the color grading method of black tea infusion, the transmission percentage of the infusion of 222 samples collected from 1954 to 1955 was determined by an electric photometer with the three filters (cobalt-blue, blue, and red) and a cuvett of 10 mm. depth.The percentages of white, black and color components were determined by the OSTWALD'S method. The ratios of transmission values through the cobalt-blue filter to those through the blue one (C/B) were calculated for expressing the color composition. And the relation between the ratio and the sensory estimation of these infusions was examined.<BR>2. The sensory estimation had a negative correlation with the percentage of white component, while a positive one with the percentage of black or color component. It was considered that the color of black tea infusion could be estimated by the ratio of color component.<BR>3. The color composition of black tea infusion could be estimated by the C/B value, when the ratio was less than 0.95, the color was yellowish, and when more than 0.99 it was reddish.<BR>4. The color of infusion of excellent black teas had the value of less than 30%, less than 10%, and more than 60% of white, black and color components respectively, and the C/B ratio was more than 1.0.
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