DECAY AND RESIDUE DYNAMICS OF 25% PROCHLORAZ EC IN MANDARIN ORANGE BY SIMULATING POSTHARVEST TREATMENT AT DIFFERENT STORAGE TEMPERATURES

Abstract

ABSTRACT Prochloraz is a fungicide that is widely used in citrus storage for attaining fruit disinfection. In this study, a gas chromatography method for determining prochloraz residues in mandarin orange by derivatization reaction of prochloraz into its main metabolite, 2,4,6-trichlorophenol, was validated. Prochloraz residue levels in postharvest mandarin oranges at room temperature and cold storage were examined at recommended label use and exaggerated dosage. The results showed that the residue of prochloraz was found to be mostly distributed in mandarin orange peel. The decay rate of prochloraz in mandarin orange stored at room temperature was slightly faster than that in a refrigerator. It demonstrated that residue decay in pulp was slightly slower than that in the whole fruit. When treated with dipping application at 0.5 or 1 g/L dosage, final residues of prochloraz in mandarin oranges were found to be from 0.09 to 1.29 mg/kg at different storage conditions and intervals, which were far below the Codex MRL of 10 mg/kg. Residues at intervals of more than 7 days would be unlikely to pose any public health concerns if prochloraz was used according to the recommended use pattern at room temperature or cold storage. PRACTICAL APPLICATIONS Prochloraz is a fungicide that is widely used in citrus storage for preventing fruit disinfection. The present study was designed to evaluate the residue decay and final residue levels of prochloraz in postharvest mandarin orange (at different storage temperatures) at different sampling time, thus to confirm and recommend the safe use pattern of prochloraz for application in citrus fruits.