Monitoring the behavior of imazalil and its metabolite in grapes, apples, and the processing of fruit wine at enantiomeric level

Dissipation behavior and risk assessment of imidacloprid and its metabolites in apple from field to products

Pesticides play vital roles in controlling pests and boosting crop yields. Imidacloprid is widely used all over the world and may form in agricultural products. The presence of pesticide residues in apples raises serious health concerns. Understanding the residual fate of imidacloprid is critical for food safety and human health. In this study, the dissipation behavior, metabolism, household processing and risk assessment of imidacloprid and its metabolites in apple were investigated from filed to products. Field experiment results suggested that the half-lives of imidacloprid at 5 times the recommended dosage was 1.5 times that of the standard dosage. And the final residues of imidacloprid were less than the established maximum residue limits (MRLs). Clarification and simmering had little effect on the reduction the residues of imidacloprid and its metabolites. The calculated processing factors were lower than 1 for imidacloprid and its metabolites, implying that the residual ratios of imidacloprid and its metabolites in each steps of the food processing were reduced. The risk quotients were <1 for all Chinese people, indicating that acceptable risks associated with dietary exposure to imidacloprid in apple. However, the higher risks were observed in young people than adults, and females faced higher risks than males. Given high residue levels in pomace, imidacloprid and its metabolites should be further studied in commercial byproducts.

Dissipation, residues, and evaluation of processing factor for spirotetramat and its formed metabolites during kiwifruit growing, storing, and processing

Spirotetramat is widely used around the world to control sucking pests and may form in agricultural products. In the current study, the dissipation, residues, and evaluation of processing factor (PF) for spirotetramat and its formed metabolites were investigated during kiwifruit growing, storing, and processing. The residue analysis method was established based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with a QuEChERS method to detect the residues of spirotetramat and its metabolites in kiwifruit and its processed products. The method provided recoveries of 74.7-108.7%, and the relative standard deviations (RSDs) were 0.6-13.1%. The LOQs of spirotetramat and its four metabolites were 1 μg kg-1. The degradation of spirotetramat was best fitted for the first-order kinetics model with a half-life of 9.90-10.34 days in the field and 24.75-30.13 days during storage. Residues of spirotetramat and its formed metabolites in kiwifruit would not pose dietary risk to consumers. Moreover, the peeling and fermentation were the highest removal efficiency for the spirotetramat and its formed metabolite residues during processing. The PF values calculated after each individual process were < 1, indicating a significant reduction of residues in different processing processes of kiwifruit. The spirotetramat was degraded during kiwifruit wine-making process with half-lives of 3.36-4.91 days. B-enol and B-keto were the main metabolites detected in kiwifruit and its processed products. This study revealed the residues of spirotetramat and its formed metabolites in kiwifruit growing, storing, and processing, which helps provide reasonable data for studying the dietary risk factors of kiwifruits and products.

Gold nanoparticle-based immunochromatographic assay for rapid detection of imazalil

Imazalil (IMZ) is a commonly used fungicide for controlling fungus in agriculture, leaving residual IMZ in crops that could be hazardous to human health. In this work, we designed IMZ haptens for mice immunization and prepared sensitive monoclonal antibody (mAb) against IMZ. The subtype of anti-IMZ mAb is IgG2a. It possessed a half inhibition concentration (IC50) of 0.95 ng mL-1 and showed no cross-reactivity against other chemicals in ic-ELISA. Taking advantage of the mAb, we developed a gold nanoparticle-based immunochromatographic assay (GICA) for the rapid detection of IMZ in grapes and tomatoes. The assay gave a visual limit of detection (vLOD) of 25 ng g-1 and cut-off value of 500 ng g-1 in both samples. According to the calibration curves, the calculated LOD were 4.12 ng g-1 and 4.70 ng g-1 in grapes and tomatoes, respectively. The recovery rates of IMZ ranged from 84.7% to 104.4% with variation coefficients (CVs) of 5.7-11.8% in spiked samples, indicating a potent practicability of the GICA. The whole GICA process took 30 min. Therefore, the developed assay can be used for on-site detection and quantitation of IMZ in grape and tomato samples.

Occurrence and impact of carbendazim and hymexazol residues on yeast growth and ochratoxin A contamination during wine production

BACKGROUND

Grapes are highly vulnerable to infection by carbon black aspergilli, which produce ochratoxin A (OTA), a mycotoxin. Carbendazim and hymexazol are widely applied to control grape diseases. Howerver, fungicides, toxigenic fungi, and OTA can be transferred from grapes to wine causing potential safety issues. The impact of these residues on fungal populations and OTA during vinification are currently unclear. Here we investigated the effects of carbendazim and hymexazol on the viability of Aspergillus carbonarius and OTA contamination during an indoor wine-processing experiment.

RESULTS

The population size of A. carbonarius substantially increased at 24 h followed by a significantly decreased at 72 h after destemming and crushing. However, carbendazim and hymexazol notably inhibited the growth of A. carbonarius in must samples. In addition, yeast growth was substantially deleyed by carbendazim, hymexazol, and OTA during the first 3 days in compared with the control. Carbendazim, hymexazol, and OTA residues declined over time, and the processing factors (PFs) for carbendazim and hymexazol throughout vinification were 0.164, 0.074, and 0.185-0.476, respectively. Carbendazim and hymexazol each reduced OTA concentrations. However, there was no significant difference after 48 h. Addition of carbendazim or hymexazol significantly reduced the level of A. carbonarius but had no significant effect on the final concentration of OTA in mature wine.

CONCLUSION

The wine-making process can reduce the residues of OTA, carbendazim, and hymexazol in grapes, but it is recommended that grapes chosen to make wine should be free of A. carbonarius contamination. © 2023 Society of Chemical Industry.

The interaction effects of pesticides with Saccharomyces cerevisiae and their fate during wine-making process

Pesticide residues in grapes could be transferred to fermentation system during the wine-making process, which may interfere the normal proliferation of Saccharomyces cerevisiae and subsequently affect the safety and quality of wine products. However, the interaction between pesticides and Saccharomyces cerevisiae is still poorly understood. Herein, the fate, distribution and interaction effect with Saccharomyces cerevisiae of five commonly-used pesticides during the wine-making process were evaluated. The five pesticides exerted varied inhibition on the proliferation of Saccharomyces cerevisiae, and the order of inhibition intensity was difenoconazole > tebuconazole > pyraclostrobin > azoxystrobin > thiamethoxam. Compared with the other three pesticides, triazole fungicides difenoconazole and tebuconazole showed stronger inhibition and played a major role in binary exposure. The mode of action, lipophilicity and exposure concentration were important factors in the inhibition of pesticides. Saccharomyces cerevisiae had no obvious impacts on the degradation of target pesticides in the simulated fermentation experiment. However, the levels of target pesticides and their metabolite were significantly reduced during the wine-making process, with the processing factors ranged from 0.030 to 0.236 (or 0.032 to 0.257) during spontaneous (or inoculated) wine-making process. As a result, these pesticides were significantly enriched in the pomace and lees, and showed a positive correlation (R² ≥ 0.536, n = 12, P < 0.05) between the hydrophobicity of pesticides and distribution coefficients in the solid-liquid distribution system. The findings provide important information for rational selection of pesticides on wine grapes and facilitate more accurate risk assessments of pesticides for grape processing products.

Stereoselective behavior and residues of the imazalil during strawberry growth and strawberry wine production

Imazalil is a chiral fungicide widely used to protect strawberries against gray mold, which may pose threats to food safety. This study aims to investigate the stereoselective behavior of imazalil during strawberry growth and strawberry wine production. A method was proposed and validated for the extraction and quantitative analysis of imazalil residues in strawberry, strawberry pomace, and strawberry wine by using ultra-high performance liquid chromatography-tandem mass spectrometry. The method exhibited mean recoveries ranging from 86.2% to 119.7% with relative standard deviations of 0.1-11.3%. The dissipation curve of imazalil during strawberry growth followed the first-order kinetic model with a half-life ranging from 6.5 to 7.1 days. Significant enantioselectivity of imazalil was observed in strawberry grown under field conditions and strawberry wine production process, with enantiomeric fraction values ranging from 0.51 (2 h) to 0.42 (27d) and from 0.48 (0d) to 0.52 (10d), respectively. (+)-imazalil was preferentially degraded in strawberry under field conditions, while (-)-imazalil was preferentially degraded during the fermentation process. The processing factor was lower than 1 for each procedure, indicating that the wine-making process can reduce imazalil residue in strawberry. These findings may facilitate a more accurate risk assessment of imazalil and provide important guidance for the safe and efficacious use of imazalil in agriculture.