Reduction of some insecticide residues from grapes with washing treatments

Abstract

Insecticide application is the most common method of insect control in agriculture. Efficiency of washing treatments in reduction of insecticide (chlorpyrifos-methyl and lambda-cyhalothrin) residues from grapes were investigated in this study. The trial was established in a Sultana seedless vineyard in Sarıgöl District, Manisa Province, Turkey in 2020. Method verification was performed with the recovery, limit of quantification and precision. Pesticide-free grapes were spiked with 0.5, 1 and 5 times of MRL for pesticides. The recovery of chlorpyrifos-methyl and lambda-cyhalothrin were 102 and 101% respectively. QuEChERS method yielded an overall-recovery of 101%. These figures were within the SANTE recovery limits (60-140%) and the detection limits of the insecticides were below the MRLs. Grapes in a vineyard were sprayed with insecticides four times and harvested 0, 2, 4 and 7 d after the last spray. Washing (tap water, citric and acetic acid) and ultrasonic cleaning treatments were applied to harvested grapes. Washing treatments decreased residue levels and reductions increased with prolonged washing durations. Reductions also decreased with prolonged harvest durations from the last spray. The citric and acetic acid washing, and ultrasonic-cleaning methods provided more efficient reduction than washing with tap water.