The effects of microwave-baking and oven-baking on thiabendazole residues in potatoes

The effect of microwave- and oven-baking on residues of the postharvest fungicide thiabendazole (E 233) in potatoes was investigated by comparing amounts present in raw, microwave- and oven-baked tubers. The levels of residues in the whole potato tubers were based on the determination of thiabendazole in peelings and flesh of potato tubers by reversed-phase HPLC analysis with fluorescence and UV detection after extraction with dichloromethane in the presence of anhydrous sodium sulphate. Amounts of thiabendazole determined after microwave- and oven-baking showed that thiabendazole was predominantly retained in the peelings (96.3-98.8%) and not lost during the two types of processing treatments at ca. 100 degrees C. Thus residues did not migrate into the flesh of the tubers.