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Analysis of chemical components in oolong tea in relation to perceived quality

Authors

  • Kunbo Wang,

    1. Key Laboratory of Tea Science of Ministry of Education & Hunan Province Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan 410128, China
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  • Fang Liu,

    1. Key Laboratory of Tea Science of Ministry of Education & Hunan Province Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan 410128, China
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  • Zhonghua Liu,

    Corresponding author
      Fax: +86 73184635306; e-mail: zhonghualiu163@163.com
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  • Jianan Huang,

    Corresponding author
      Fax: +86 73184635306; e-mail: zhonghualiu163@163.com
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  • Zhongxi Xu,

    1. Key Laboratory of Tea Science of Ministry of Education & Hunan Province Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan 410128, China
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  • Yinhua Li,

    1. Key Laboratory of Tea Science of Ministry of Education & Hunan Province Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan 410128, China
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  • Jinhua Chen,

    1. Key Laboratory of Tea Science of Ministry of Education & Hunan Province Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan 410128, China
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  • Yushun Gong,

    1. Key Laboratory of Tea Science of Ministry of Education & Hunan Province Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan 410128, China
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  • Xinghe Yang

    1. Key Laboratory of Tea Science of Ministry of Education & Hunan Province Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, Hunan 410128, China
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Fax: +86 73184635306; e-mail: zhonghualiu163@163.com

Summary

Properties of leaf and infusion colours, chemical components and volatile flavour compounds of oolong teas and their correlation with perceived quality score given by tea-tasting panel were analysed. The scores for appearance and infused leaf correlated strongly with concentrations of chlorophyll a (chl a), chlorophyll (chl b) and chlorophyll (chl) (= 0.355–0.433, < 0.05) and the total quality score (TQS) positively correlated with concentrations of chl a, chl b and chl (= 0.517–0.533, < 0.01). The perceived taste score and TQS positively correlated with the concentration of total free amino acid (= 0.514, 0.694, < 0.01) and theanine (= 0.500, 0.684, < 0.01). The volatile composition and their quantities varied widely among oolong tea samples. Nerolidol, indole, benzeneacetaldehyde, linalool, linalool oxide I, hexanal, benzyl nitrile, geraniol and 1-penten-3-ol were prevailing volatile compounds detected in most of oolong tea samples. Principal component analysis screened ten principal components with the first three (glutamic acid, total catechins and benzeneacetaldehyde) explaining 27.86%, 20.00% and 14.46% of the total variance, respectively. Regression analysis upon the ten principal components formulated a prediction model on the total quality score with 78.5% probability. The result showed that oolong teas could be partially classified by cluster analysis based on principal components.

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