Pesticides which are diluted and sprayed according to the pre-harvest interval (PHI) are generally decomposed and lost through various factors and pathways, and the leftover pesticides are known as residual pesticides. This study aims to determine the dissipation of residual amounts of dinotefuran, fluazinam, indoxacarb, and thiacloprid in persimmon and the changes in the concentration of various processing products. Pesticide spraying is performed in accordance with the GAP (good agricultue practice) of Korea, and the processed products are manufactured using a conventional method after removing the skin of persimmons. The modified QuEchERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method and an optimized method using LC-MS/MS (liquid chromatography mass spectrometry) is implemented to analyze the residual pesticides. The linearity, recovery, and LOQ (limit of quantitation) are presented to verify the analysis method. The amount of residual pesticides tested decreases significantly in a time-dependent manner, regardless of the minimal dilution effect present due to growth. The residual concentration does not vary significantly during the processing stage despite the removal of the systemic pesticides, dinotefuran and thiacloprid. The residues of non-systemic pesticides, fluazinam and indoxacarb, are typically removed by the peeling removal and processing methods. The reduction factor of dinotefuran, whose residual concentration is increased, is less than 1, and the absolute amount of pesticides is decreased through processing. The results of this study can be used as the scientific basis data to ensure the safety of residual pesticides in processed products in the future.

This study aimed to evaluate residue changes in flubendiamide and tebufenozide during the processing of whole grain into milled rice, cooked rice, and rice cake, and to calculate their processing factors (PFs). For the processing study, pesticides were applied at three times the recommended rate based on Korea’s good agricultural practice (GAP), and processed products were prepared using conventional methods. Residual pesticide analysis was performed using a modified QuEChERS method and LC-MS/MS. The residue analysis method was validated based on parameters including LOQ, linearity, and accuracy at the LOQ, 10LOQ, and MRL levels, with the LOQ set at 0.01 mg/kg for all samples. During milling, which removes the hull, more than 90% of the pesticide residues were eliminated. Additional reductions exceeding 50% were observed during cooking and rice cake processing. All PFs, except for those in the hulls, were less than 1, indicating that processing reduces pesticide levels. Despite the use of threefold the GAP rate, the %ADI values for all processed products remained below 1%, suggesting negligible dietary risk. These findings provide scientific evidence supporting the safety of processed rice products regarding pesticide residues and highlight the importance of considering processing effects in dietary exposure assessments.

Rice processing can substantially alter pesticide residues before consumption. This study evaluated the residue behavior of buprofezin and etofenprox during rice processing, determined their processing factors (PFs), and assessed dietary exposure through rice and processed rice products. To ensure quantifiable residues throughout the study, both pesticides were applied at three times the recommended Korean good agricultural practice (GAP) rate. Relative to whole grain, buprofezin and etofenprox residues decreased by 91.9% and 96.8% in husked rice, respectively, with the greatest overall reductions observed in polished rice (99.0% and 99.5%, respectively). In contrast, higher residue concentrations were observed in hulls, with PFs of 6.45 for buprofezin and 3.60 for etofenprox. Cooking further reduced residues remaining in husked rice, whereas both pesticides were below the limit of quantification (LOQ) in cooked polished rice and rice cake. Despite application at three times the recommended GAP rate, estimated chronic dietary exposure was low, with maximum percentage of acceptable daily intake (%ADI) values of 1.303% for buprofezin and 0.261% for etofenprox. These findings indicate that milling was the predominant processing step reducing pesticide residues in edible rice fractions, and cooking provided an additional reduction before consumption.