| The caffeine of tea is one of the three main ingredients to determine the quality of tea, it is not only the characteristics of the material in the chemical constituents of tea, but also leaving from other plants and becoming the main reason for drinks, it has important pharmacological effects. In this study, three aspects were inspected and analyzed about caffeine contents of Oolong tea in Fujian province. First of all, analyzed the caffeine content of fresh leaves, stems and raw tea through random sampling in the main producing areas in Fujian province; secondly, researched on the caffeine contents of Export Oolong tea and explored the correlation between the caffeine contents and the quality of tea; Finally, explored baking to the coffeine contents and quality of Oolong tea influence using Wuyi Narcissus and Tieguanyin as test materials.The main results were as follows:1 Studies on the coffeine contents of Oolong tea in FujianThis study used main representative cultivars in main production areas of Oolong tea as experiment materials. A systematic analysis aimed at caffeine contents of Oolong tea. The results showed that: (1) the basic situation of caffeine contents of Fujian Oolong tea: the caffeine content of fresh leaves (3.52%) > the caffeine content of raw teas (2.99%) > the caffeine content of made teas (2.97%)> the caffeine content of tea-stalks (1.74%), which showed that there were significant differences between the different materials; (2) the differences of caffeine contents in different maturity of fresh leaves: the caffeine content of tea new shoots (4.14%)> the caffeine content of in bud(3.14%), which showed that there were significant differences in different maturity of fresh leaves; (3) the differences of caffeine contents in different tea producing areas: the caffeine content of fresh leaves: Wuyishan>Jianou>Anxi>Huaan, the caffeine content of raw teas: Anxi>Wuyishan>Jianou>Huaan, which showed that there were significant differences in different tea producing areas; (4) the differences of caffeine contents in different seasons: the caffeine content of fresh leaves: spring> autumn> summer, the caffeine content of raw teas: spring> summer> autumn, which showed that there were significant differences in different seasons; (5) the differences of caffeine contents in different cultivars: the caffeine content of Rougui was the highest in fresh leaves, and the caffeine content of Dahongpao was the highest in raw teas. There were significant differences between Rougui and Huangdan in he caffeine content of fresh leaves. In caffeine content of raw teas, there were significant differences between Dahongpao and Minnan Narcissus. Through the cluster analysis, different Oolong tea cultivars were divided into 3 groups (the high coffeine content, the medium coffeine content, the low coffeine content) according to coffeine contents.2 Studies on the coffeine content and quality of export Oolong teaThis study used Minnan Narcissus, Tieguanyin, Sezhong, Wuyi Narcissus, Minbei Narcissus, Minbei Oolong as theexperiment material. The coffeine content and quality of export Oolong tea was researched. The results showed: the caffeine content of Wuyi Narcissus (3.35%) > the caffeine content of Minbei Oolong (3.20%) > the caffeine content of Sezhong (3.13%)> the caffeine content of Minbei Narcissus (2.84%)> the caffeine content of Minnan Narcissus (2.67%) > the caffeine content of Tieguanyin (2.56%). The caffeine content of Oolong tea in the north of Fujian was more than that of Oolong tea in the south of Fujian.The relative coefficient was up to 0.981 between the caffeine content and the quality of Oolong tea in the south of Fujian. The relative coefficient reached to 0.634 between the caffeine content and the quality of Oolong tea in the north of Fujian. Obviously, There were certain correlations between the coffeine content and quality of export Oolong tea.3 Studies on the coffeine content and quality of Oolong tea in baking technology to Wuyi Narcissus and Tieguanyin(1) Effects of baking technology on the coffeine content and quality of Wuyi NarcissusThis research carried on baking treatment by using 90℃, 110℃, 130℃, 150℃,1h, 2h, 3h, 4h to Wuyi Narcissus in spring. This research carried on baking treatment by using 90℃, 110℃, 130℃, 150℃,1h, 3h, 5h, 7h to Wuyi Narcissus in summer. The results showed that the caffeine content of all treatments was lower than that of the control. With temperature rising and time prolonging, the coffeine content was gradually decreased.The caffeine content of Wuyi Narcissus in spring and summer: 90℃> 110℃> 130℃> 150℃,1h>2h>3h>4h. The decreasing range of caffeine content under different baking temperature and time: Spring < Summer. It had a great effect on the caffeine content baking 1h, 7h in 90℃,130℃,150℃. After fuzzy comprehensive evaluation and sensory evaluation, we discoveried that the processing of 90℃for 3h of the quality of Wuyi narcissus in spring was the optimum; the processing of 130℃for 7h of the quality of Wuyi narcissus in summer was the best. It indicated that there was certain influence between baking and the coffeine content and the Oolong tea quality.(2) Effects of baking technology on the coffeine content and quality of TieguanyinThis research carried on baking treatment by using 60℃, 80℃, 100℃, 120℃,1h, 2h, 3h to Tieguanyin in spring and autumn. This research carried on baking treatment by using 80℃, 100℃, 120℃, 130℃,1h, 2h, 3h to Tieguanyin in summer. The results showed that the caffeine content of all treatments was lower than that of the control. With temperature rising and time prolonging, the coffeine content was the tendency which roughly reduced gradually. When the temperature of baking was higher and the time was longer, the coffeine content's loss was more during different seasons, therefore, spring>autumn>summer. After fuzzy comprehensive evaluation and sensory evaluation,we discoveried that the processing of 100℃for 2h of the quality of Tieguanyin in spring was the optimum; the processing of 120℃for 2h of the quality of Tieguanyin in summer was the optimum.The processing of 100℃for 3h of the quality of Tieguanyin in autumn was the best.In addition, the influences of the proportion of time segment between the high temperature and the low temperature, the high temperature, the low temperature, the change rule of temperature on the baking of Oolong tea using Tieguanyin as the materia1. The results showed that the high temperature was the biggest influence on the coffeine content, next was the low temperature, the change rule of temperature, the proportion of time segment between the high temperature and the low temperature. The proportion of time segment (1:3) had a greater effect on the caffeine content than that of 2:2. The change rule of temperature had a greater effect on the caffeine content than that of proportion of time segment (1:3). This orthogonal test found that the quality of Tieguanyin of baking for 2h in 100℃then baking for 2h in 60℃was the optimum. |
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