Behavior of residual organophosphorus pesticides in foodstuffs during leaching or cooking

The relationship between cooking procedure and pesticide species on pesticide residues in raw crops was examined using pesticide-containing commercial green tea leaves, spinach, strawberries, oranges, and grapefruit. The residual organophosphorus pesticides in green tea leaves and in crops were decreased on leaching or cooking, and the rate of decrease was closely related to the octanol-water partition coefficient. The regression expression log(L(r)) 2.25 - 0.312 log K-ow, r = 0.923, where L(r) is the translocated pesticide concentration in drawn tea (%) and K-ow is the partition coefficient (octanol/water) of the pesticide, was shown from the relationship between the amount of organophosphorus pesticides in the tea- leaves and the amount dissolved into the brewed tea. On the other hand, the decrease of organophosphorus pesticide residues in spinach after 5 min of boiling or in an orange after cooking and the pesticide K-ow fit the equation log(P-r) = 1.59 + 0.06 log K-ow, r = 0.991, in boiled spinach, log(P-r) = 0.51 + 0.40 log K-ow, r = 0.978, in orange marmalade, and log(P-r) = -5.28 + 2.12 log K-ow, r = 0.946, in orange candied peel, where P-r is the percent of pesticide remaining in the fresh state. The pesticide remained in the processed food according to the K-ow expression. The relationship was similar for the pesticide residues after repeated cooking by boiling, frizzling, or frying.