Effects of household washing methods and post-ripening on the residue dissipation of the systemic fungicides mandestrobin and metconazole in Persimmons

Studies evaluating the efficiencies of removing mandestrobin (MAND) and metconazole (MEZ) residues from persimmons using household washing methods are lacking. Therefore, in this study, the efficiencies of household washing processes in removing the systemic fungicides MAND and MEZ from persimmons (Diospyros kaki Thunb) and their dissipation characteristics during postharvest ripening were investigated. Following immersion, the initial residues were mainly distributed in the calyx (64.2-79.9%), followed by the peel (17.3-22.7%) and flesh (2.8-13.1%). Among the various washing methods, hand rubbing under running water yielded the highest MAND removal efficiency (78.9%) from the whole fruits, particularly from the peel (74.6%). Whereas MEZ removal was independent of the washing method (except for washing under running tap water; removal rate of 33.7%), with reductions of 51.9-58.8% within the whole fruits, baking soda was the most effective for the peel. Overall, hand rubbing under running tap water was an accessible, green approach. The residue levels exhibited no significant reductions over 21 d of ripening, and the respective biological half-lives of MAND and MEZ based on the amounts of the residues were 132.7 and 27.4 d, indicating extremely slow dissipation. These findings provide scientific guidance for effective washing practices and the improved assessment of pesticide exposure when using persimmons.