The decrease in pesticides in fruit and vegetables during commercial processing

Samples of tomatoes, peppers, asparagus, spinach and peaches were exposed to three insecticides (acephate, chlorpyrifos and cypermethrin), three ethylenebisdithiocarbamate fungicides (mancozeb, maneb, propineb) and the tetramethyldithiocarbamate fungicide thiram to study the effect of commercial processing on the residues. In most cases, canning operations led to a gradual decrease in residue levels in the finished products, particularly through washing, blanching, peeling and cooking processes. The results indicated that washing plus blanching led to more than 50% loss in pesticide residues, except for in peaches. Ethylenebisdithiocarbamates (EBDCs) were completely removed from tomatoes and spinach by washing followed by hot water blanching. The total amount of pesticide removed by all of the combined canning operations ranged from 90 to 100% in most products. Pepper retained 61% of chlorpyrifos but these residues disappeared during 3-month storage of finished cans. Acephate showed a surprising tenacity in peaches, as 11% of the original residues were still present in 2-year stored cans.