利用气相色谱-串联质谱联用仪监测了茶树鲜叶及其绿茶加工中多环芳烃（PAHs）的残留水平。结果表明,不同地区茶树一芽二叶样品PAHs含量差异明显,产地环境PAHs污染程度对茶鲜叶PAHs含量影响较大。茶芽、嫩叶、老叶PAHs含量分别在40.5~52.8βμg·kg-1、50.0~67.4βμg·kg-1和91.5~97.6βμg·kg-1之间,PAHs含量大小顺序为老叶>嫩叶>芽。汽车尾气对交通公路旁茶树芽和嫩叶PAHs含量影响较大,且对50βm范围内茶树鲜叶影响更明显。电加热干燥模式下,水分散失和PAHs挥发是影响绿茶加工过程中PAHs含量的两个关键因子。加工环节过后,茶叶PAHs含量由61.0βμg·kg-1上升到166.1βμg·kg-1。摊放和干燥过程中PAHs大量挥发,造成茶叶干重中PAHs残留量由292.0βμg·kg-1降低到171.9βμg·kg-1。
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.
关键词
残留水平 /
多环芳烃 /
绿茶加工 /
汽车尾气 /
鲜叶
Key words
fresh leaves /
green tea manufacture /
polycyclic aromatic hydrocarbons /
residue level /
vehicle exhaust
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基金
中国农业科学院创新团队茶叶质量与风险评估团队（CAAS-ASTIP-2014-TRICAAS-06）、浙江省公益应用项目（2017C32059）、现代农业产业技术体系建设专项基金资助项目（nycytx-26）
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