Appearance color measurement of commercially available green teas and application to the evaluation of tea quality using a color difference meter
2001
Kohata, K. (National Research Inst. of Vegetables, Ornamental Plants and Tea, Ano, Mie (Japan)) | Yamashita, Y. | Yamaguchi, Y. | Horie, H.
Comparison of appearance color values in four different green tea types (Matcha, Gyokuro, Sencha and Fukamushi sencha) as well as based in tea grades according to the market price has been that (a) Powdered tea samples gave higher appearance color values than non-powdered ones except for h (hue angle) values. (b) Matcha showed the highest values for all of them, as evidenced by the brightest and the most greenish color. (c) L*(lightness), C*(chroma), h and b*(yellow (+) and blue (-) chromaticity) values reflected the duller and more greenish color of Gyokuro and the lighter and more yellowish color of Fukamushi sencha. (d) It is preferable to use the h value as an indicator for the evaluation of the control of the quality of both powdered and non-powdered teas, since the h value showed significant differences between the upper and lower grades in all the four green teas. (e) There was a highly positive correlation between the h value and the content of chlorophyll (a + a') and a negative correlation between the h value and the changes in the rate of chrolophyll into pheophytin in all the green teas except for Gyokuro, suggesting that the content of chlorophyll (a + a') reflected more the appearance color than that of pheophytin (a + a'). These results indicate that the color difference meter could be applied to the evaluation of the quality of both powdered and non-powdered green teas.
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