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Journal of Tea Science ›› 2017, Vol. 37 ›› Issue (2): 191-200.

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Residue Pattern of Polycyclic Aromatic Hydrocarbons in Tea Leaves during Green Tea Manufacturing Process

GAO Guanwei1,2, CHEN Hongping1, LIU Pingxiang1,2, MA Guicen1, HAO Zhenxia1, WANG Chen1, CHAI Yunfeng1, LU Chengyin1,*   

  1. 1. Tea Research Institute, Chinese Academy of Agricultural Sciences, Tea Quality and Supervision Testing Center, Ministry of Agriculture R. P. China, Hangzhou 310008, China;
    2. Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
  • Received:2016-11-09 Revised:2016-11-30 Online:2017-04-15 Published:2019-08-22

Abstract: Residues of polycyclic aromatic hydrocarbons (PAHs) in fresh tea leaves and green tea during manufacturing process were determined by gas chromatography-tandem mass spectrometry. Results showed that considerable variations of PAHs were identified in tea samples (a bud and two leaves) from different locations, indicating the contamination levels in the tea producing areas might significantly affect PAH residues in fresh tea leaves. The variations of PAHs contents in tea buds, tender leaves and mature leaves were 40.5-52.8βμg·kg-1, 50.0-67.4βμg·kg-1 and 91.5-97.6βμg·kg-1, respectively. The order of PAHs contents follows as mature leaves>tender leaves>tea buds. Vehicle exhaust was hypothesized to have a direct effect on PAH residues in tea buds and tender leaves, as their levels were extremely high within 50βm around the roads. During the green tea manufacturing process, evaporation of moisture and PAHs by electric heating were the key factors affecting PAHs residues, which increased from 61.0βμg·kg-1 to 166.1βμg·kg-1 in tea samples. Moreover, PAH residues might evaporate during the spreading and drying processes, which decreased from 292.0βμg·kg-1 to 171.9βμg·kg-1.

Key words: polycyclic aromatic hydrocarbons, vehicle exhaust, fresh leaves, green tea manufacture, residue level

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