茶の加工工程および熱湯浸出時における農薬の消長

摘要

3種の殺虫剤クロルフェナピル，ピリミホスメチルおよびクロチアニジンをチヤに散布して被覆下で栽培し，摘採後の茶の加工工程および熱湯浸出時における農薬の消長を調査した.生茶葉に加熱や発酵などの加工工程が入ることで，加工茶における農薬残存率は減少したが，加熱時間や発酵時間が長く，熱が茶葉へ伝わりやすいほど減少した.また，普通煎茶において3農薬の農薬残存率に有意差は認められなかったが,ネオニコチノイド系のクロチアニジンのように，オクタノール/水分配係数が低く水溶性の高い農薬ほど，茶浸出液への移行率が高くなる傾向が見られた.一方，粒度による農薬移行率に有意な差は認められなかった.%The effects of processing to produce various types of tea or infusion on the levels of pesticide residues in tea were investigated for three insecticides (chlorfenapyr, pyrimiphos-methyl, and clo-thianidin). Tea plants were sprayed with one of the three pesticides and cultivated under cover. The levels of pesticide residues in tea decreased after processing according to the time and temperature of heating, as well as fermentation. Although significant differences were not observed among the three pesticides in the ratio of decreased of pesticide concentration after processing to green tea, clothianidin, which is a neonicotinoid insecticide and has alower log Pow value, tended to be transferred more than the other two insecticides into infusions. However, no significant difference in the ratios of clothianidin transferred to infusions was observed among green tea with three different leaf sizes.