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Estimation of tea quality by infusion colour difference analysis
Author(s) -
Liang Yuerong,
Lu Jianliang,
Zhang Lingyun,
Wu Shan,
Wu Ying
Publication year - 2004
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.1953
Subject(s) - black tea , green tea , food science , significant difference , chemistry , distilled water , theaflavin , mathematics , polyphenol , statistics , chromatography , biochemistry , antioxidant
The colour differences in terms of Δ L , Δ a , Δ b and Δ E between distilled water and infusions of 29 green teas, 16 black teas and 13 oolong teas and their correlation with sensory quality attributes of tea were investigated. The results showed that the Δ L value decreased but the Δ a , Δ b and Δ E increased with the degree of fermentation of the three kinds of tea. The Δ L was positively correlated to quality attributes of green tea and oolong tea but negatively correlated to those of black tea. The Δ a of tea infusions is a reliable descriptor to differentiate among green and black teas. The regression of total quality score of green tea (TQSg) upon the Δ a was TQSg = −2.26Δ a + 77.2 ( R 2 = 0.22, p < 0.01), that of total quality score of black tea (TQSb) upon Δ b was TQSb = 0.70Δ b + 44.6 ( R 2 = 0.31, p < 0.05) and that of total quality score of oolong tea (TQSo) upon Δ L was TQSo = 1.09Δ L + 94.5 ( R 2 = 0.75, p < 0.01). Because the infusion colour difference indicators of Δ a , Δ b and Δ L can be done rapidly, it could be very useful for on‐site or on‐line quality monitoring during tea manufacture and storage. Copyright © 2004 Society of Chemical Industry