乌龙茶中多种农药残留的浸出及安全性

Leaching characteristics and safety of multi pesticides residue in ololong tea during infusing

以3个梯度浓度,含有杀螨剂、有机磷、噻二嗪酮类、拟除虫菊酯类7种农药的乌龙茶为对象;通过测定茶粉、整叶茶两种形态,经100℃开水浸泡获取的茶汤农药残留量,来研究茶叶形态、农药属性、背景浓度对农药浸出的影响,并评价茶汤中农药残留饮用安全性。结果表明,3个浓度的整、碎乌龙茶中,7种农药的浸出率分别为2.0%~16.7%和0.3%~9.7%。整叶茶农药的浸出量仅为茶粉的9.2%~58.1%。农药浸出率受农药溶解度和辛醇-水分配系数影响。除了三唑磷超标外,乌龙茶中其它浸出农药残留值均达到中国和日本限量标准要求。3个梯度浓度乌龙茶茶粉、整叶茶浸出的农药残留单点单项风险指数（SRI）、整体风险指数（TRI）均小于1,饮用较安全。

The leaching characteristics and safety evaluations of 7 pesticide residues including acaricide, organophosphorous pesticide, buprofezin, and synthetic pyrethroid pesticide in Oolong tea were studied in this work. The pesticide residues in tea infusions prepared from the whole leaf tea and the broken leaf tea by being brewed in 100℃ boiling water were determined, respectively. The effects of tea morphology, pesticide property, and background concentration on the leaching of pesticides were studied and the impact of pesticide residues on the safety of tea drinking was evaluated. The results showed that the overall leaching rates of these pesticides from the whole leaf tea and the broken leaf tea into infusions were in the ranges of 2.0% - 16.7%, and 0. 3% -9. 7%, respectively. The leaching rates of pesticides for the whole leaf tea were much lower than that for the broken leaf tea （9.2% ~58.1% ）. The leaching rate of the pesticides from the Oolong tea into the infusion was dependent on the water solubility of the pesticide and its partition coefficient in the mixed solvent. Except for triazophos, the other pesticide residual values in infusions were lower than MRL value of criterion in China and Japan. The single risk index （SRI） and total risk index （TRI） of the whole leaf tea and the broken leaf tea were both lower than l, indicating that infusions from these Oolong tea were safe for drinking.