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Journal of Tea Science ›› 2010, Vol. 30 ›› Issue (5): 399-406.doi: 10.13305/j.cnki.jts.2010.05.011

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The Nonlinear Regression of Bitterness and Astringency of Main Compounds in Green Tea and the Application in Organoleptic Tests

XU Wen-ping1, LI Da-xiang1, ZHANG Zheng-zhu1, TANG Qian2, WAN Xiao-chun1,*   

  1. 1.Key Laboratory of Tea & Medicinal Plants and Product Safety,Ministry of Agriculture, Anhui Agricultural University, Hefei, 230036;;
    2. Tea Department of Horticulture College, Sichuan Agricultural University, 625014
  • Received:2010-02-05 Revised:2010-05-28 Published:2019-09-11

Abstract: The methods of quantitative response scales and sequential analysis for organoleptic tests were employed to quantitatively evaluate the bitterness and astringency of tea infusions. Flavor characteristic curves (the relationship between taste intensity and concentration) of EGCG and caffeine were established. The mathematical functions of bitterness and astringency were built based on three main compounds namely EGCG (epigallocatechin-3-O- gallate), caffeine and rutin, and the interactions of the three compounds on bitterness and astringency were examined. The results showed that rutin could increase the bitterness of caffeine, but it had no effect on flavor of EGCG, while caffeine could enhance astringency of EGCG. The functions were used to discover the mysteries of heavy bitterness and astringency of green tea produced in Sichuan province. The results from the quantification of main tastants and flavor of twenty tea samples showed that the functions could give the explanation of 78 to 137 percents to the bitterness and 68 to 144 percents to the astringency. The heavy bitterness and astringency of Sichuan green tea were mainly caused by high contents of EGCG and caffeine.

Key words: Sichuan green tea, bitterness and astringency, EGCG, caffeine, nonlinear regression analysis

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