Effects of storage and processing on the residual distribution and behavior of five preservatives and their metabolites in pomegranate.

Pomegranate are often treated with preservatives during storage. This study investigated the effects of storage and food processing on the residual behavior of the five commonly used preservatives (prochloraz, thiophanate-methyl, pyrimethanil, imazalil, and difenoconazole) and their metabolites in pomegranate and its products. The LOQs for all target compounds were 0.001 mg kg-1. The residue levels of five preservatives in the calyx was highest, followed by the peel, stalk, septum, umbilicus, and seed. For the migration ability, the five preservatives from pomegranate peel to seed was negatively correlated with their octanol/water partition coefficients. The processing factors of each procedures of juice, wine, vinegar, and pectin processing were <1. Nevertheless, the PF values in drying peel during the overall process ranged from 1.26 to 4.09. Hence, it is worth noting that consumption of pomegranate essential oil and drying peel may pose a potential risk to the health of consumers.

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.

Multivariate response surface methodology assisted modified QuEChERS method for the rapid determination of 39 pesticides and metabolites in medlar.

A modified QuEChERS method coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established for residue analysis of 39 pollutants (34 commonly used multi-class pesticides and 5 metabolites) in medlar matrices (fresh, dried, and medlar juice). Samples were extracted using water with 0.1 % formic acid: acetonitrile (5: 10, v/v). The phase-out salts and five different cleanup sorbents (including N-propyl ethylenediamine (PSA), octadecyl silane bonded silica gel (C18), graphitized carbon black (GCB), Carbon nanofiber (C-Fiber) and MWCNTs) were investigated to improve the purification efficiency. The Box-Behnken Design (BBD) study was employed for an optimal solution of the volume of extraction solvent, phase-out salt, and the purification sorbents for the analytical method. The average recoveries of the target analytes in the three medlar matrices ranged from 70 % to 119 % with relative standard deviations (RSDs) of 1.0 %-19.9 %. Screening of market samples (fresh and dried medlars) collected from the major producing regions in China showed that 15 pesticides and metabolites were detected in the samples at concentrations of 0.01-2.22 mg/kg, and none of which exceeded the maximum residue limits (MRLs) set in China. The results showed that the risk of food safety by consumption of medlar products caused by the use of pesticides was low. The validated method could be used for rapid and accurate screening of multi-class multi-pesticide residues in Medlar for food safety.

Key metabolites and mechanistic insights in forchlorfenuron controlling kiwifruit development.

Forchlorfenuron (CPPU) is a plant growth regulator widely applied on kiwifruit to improve yield, however, there are rarely reports on its effects on the nutrients of kiwifruits. Based on UHPLC-Q-TOF-MS, the effects of CPPU on metabolism profile and nutrient substances of two kiwifruit varieties during development were investigated by non-targeted metabolomics. A total of 115 metabolites were identified, and 29 differential metabolites were confirmed and quantified using certified reference standards. Metabolic profile indicated that CPPU promoted kiwifruit development during the main expansion stages at the molecular level, and the effects varied slightly for different varieties. In the early and middle stages of kiwifruit development, the anthocyanin, flavone and flavonol biosynthesis were down-regulated in both varieties, and flavanols biosynthesis was down-regulated only in Hayward variety. Arginine biosynthesis was down-regulated at all stages till the harvest. Although the synthesis of these nutrient substances in kiwifruits was mostly down-regulated by CPPU, the negative effects became mild at harvest time, and positively, the significant increase of sucrose and decrease of organic acids at harvest time could help to improve the taste of kiwifruits.

Comparison of the effectiveness of thiamethoxam and its main metabolite clothianidin after foliar spraying and root irrigation to control Myzus persicae on peach.

The green peach aphid, Myzus persicae, is one of the most economically important pests in peach-growing areas around the world. In many countries, the application of insecticides is the main method to control and reduce the population of M. persicae. In this study, we investigated the effects and persistence of thiamethoxam against M. persicae by foliar spraying and root irrigation. The residues of thiamethoxam and clothianidin in peach were determined to assess food safety. The results showed that thiamethoxam treatment significantly reduced the population of M. persicae through foliar spraying and root irrigation. And the persistence of root irrigation on M. persicae was significantly longer than that of spraying. Thiamethoxam and clothianidin were absorbed by the roots, transported to other parts of the plant, and concentrated in the leaves, especially new leaves. The final residues of thiamethoxam and clothianidin in peaches were below the maximum residue limit (MRLs). These results suggested that thiamethoxam is more effective in M. persicae control through root irrigation than foliar spraying. The persistence of root irrigation on M. persicae was significantly longer than that of spraying. These results shed some light upon the control of M. persicae by root irrigation of thiamethoxam.

The fate of thiamethoxam and its main metabolite clothianidin in peaches and the wine-making process.

Thiamethoxam is widely used to control a large number of insect pests of peach crops. Understanding the fate of thiamethoxam and its main metabolite clothianidin in field peach, during storage, and in the processing of peach wine is of vital importance for food safety. The thiamethoxam and clothianidin were separated and determined by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Field and storage results showed that the half-lives of thiamethoxam were 4.9-5.5 and 10.3-15.8 days, respectively. The processing factors (PFs) of all the wine-making procedures were less than 1, and the PFs of the overall process ranged from 0.10 to 0.47. The highest elimination rate was obtained for thiamethoxam and clothianidin during the fermentation process. The results from this study could understand the dissipation kinetics and residual levels of thiamethoxam and clothianidin in peach, and also help to accurately assess their risks in the raw and wine-making process.

Hydrolysis Kinetics of a Novel 3,4-Dichloroisothiazole Plant-Activator Candidate LY5-24-2 by UPLC-Q-TOF.

Hydrolysis characteristics of a novel 3,4-dichloroisothiazole based fungicide with activating plant defense responses as a candidate plant-activator LY5-24-2 were investigated under different conditions (pH and temperature) using ultra-performance liquid chromatography (UPLC) and quadrupole Time-of-Flight (Q-TOF). The hydrolysis case complied with the first-order kinetic model, with half-lives ranging from 4.8 h to 3.2 days at pH 4, 7, 9 and temperature at 25 and 50℃. One of the hydrolysis metabolite 3,4-dichloroisothiazole-5-carboxylic acid (metabolite 1, M1) was determined and quantified using authentic standard. The other hydrolysate 3-chloro-5-(trifluoromethyl) pyridin-2-amine (metabolite 2, M2) was determined and identified according to accurate mass information, fragmentation patterns and principle component analysis (PCA). By utilizing high-resolution mass spectrometry and multivariate statistical analysis, hydrolysis dynamic of the metabolites was characterized and figured out. This research provided a non-target screening method to analyze hydrolysis metabolites of a new plant-activator and to find its degradation products in aqueous solution.

Simultaneous determination of spirodiclofen, spiromesifen, and spirotetramat and their relevant metabolites in edible fungi using ultra-performance liquid chromatography/tandem mass spectrometry.

A fast, sensitive, and reliable analytical method was developed and validated for simultaneous identification and quantification of spirodiclofen, spiromesifen, and spirotetramat and their relevant metabolites in edible fungi by ultra-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS). First, sample extraction was done with acetonitrile containing 1% formic acid followed by phase separation with the addition of MgSO4:NaOAc. Then, the supernatant was purified by primary secondary amine (PSA), octadecylsilane (C18), and graphitized carbon black (GCB). The linearities of the calibrations for all analytes were excellent (R2 ≥ 0.9953). Acceptable recoveries (74.5-106.4%) for all analytes were obtained with good intra- and inter- relative standard deviations of less than 14.5%. The limit of quantification (LOQs) for all analytes was 10 µg kg-1. For accurate quantification, matrix-matched calibration curve was applied to normalize the matrix effect. The results indicated that the method was suitable for detecting the three acaricides and their relevant metabolites in edible fungi.

Ras/Raf/MEK/ERK pathway axis mediated neurotoxicity induced by high-risk pesticide residue-Avermectin.

Pesticide residues have become a healthy threaten of human beings. Among the pesticides, many of them have neurotoxicity. Extracellular Regulated Protein Kinases (ERK) pathway is an important signaling pathway that regulates a variety of downstream progress. In this work, peach (PRUNUS persica) and cherry (PRUNUS cerasus) were sampled from over 300 plantations in China and assessed for the residue risk. In mechanism studies, high-risk pesticide Avermectin showed a high activity inhibiting three neurotoxicity models, SH-SY5Y, PC-12 and SK-N-SH cells. At protein levels, ERK pathway proteins and their downstream proteins were obviously down-regulated. Moreover, the effects of low-dose Avermectin can be accumulated at protein levels in the low-dose long-term chronic toxicology detection.

Environmental behavior and influencing factors of glyphosate in peach orchard ecosystem.

In this paper, several experiments were carried out to study the environmental behavior and influencing factors of glyphosate (PMG) in peach orchard ecosystem. The results of field experiments showed that PMG and its metabolite aminomethylphosphonic acid (AMPA) were detected in peach tree leaves and peach tree fruits, although PMG was only sprayed on the soil. The residues of PMG and AMPA in peach tree leaves were ~0.1 mg/kg and ~0.5 mg/kg and in peach tree fruits were ~0.01 mg/kg and 0.07-0.11 mg/kg, respectively. By conducting a series of laboratory simulation experiments, the environmental factors affecting the degradation of PMG were screened and evaluated. The results showed that PMG metabolized much faster in loess soil than red soil and black soil (with the DT50 of 11.6 days, 62.4 days, and 34.1 days, respectively). By analyzing the basic properties of the soil, we investigated the effects of pH, moisture content, organic matter (exogenous biochar) and ambient temperature using orthogonal experiments, and the results were further confirmed by microbial experiment. The results showed that alkaline conditions (pH = 7.8/9), high water content (25%) and microorganisms could promote the degradation of PMG. Sterile soil environment had a negative impact on the metabolic behavior of PMG to AMPA.

Development and validation of a method for the analysis of five diamide insecticides in edible mushrooms using modified QuEChERS and HPLC-MS/MS.

In this study, a new method for simultaneous determination of cyantraniliprole, chlorantraniliprole, tetrachlorantraniliprole, cyclaniliprole and flubendiamide in edible mushrooms by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) combined with a modified QuEChERS procedure. The samples were extracted using acetonitrile and then cleaned up by primary secondary amine (PSA) and octadecylsilane (C18). The determination of these insecticides was achieved in less than 5 min using an electrospray ionization source in positive mode (ESI+) for cyantraniliprole and chlorantraniliprole, while negative mode (ESI-) for tetrachlorantraniliprole, cyclaniliprole and flubendiamide. The linearities of the calibrations for all target compounds were acceptable (R2 ≥ 0.9922). The limits of detection and quantification were 0.05-2 µg kg-1 and 5 µg kg-1, respectively. Acceptable recoveries (73.5-110.2%) were acquired for these insecticides with RSDs less than 12.7%. The results demonstrated that the proposed method was effective and convenient for the determination of these insecticides in edible mushrooms.

Development of a fast multi-residue method for the determination of succinate dehydrogenase inhibitor fungicides in cereals, vegetables and fruits by modified QuEChERS and UHPLC-MS/MS.

In this study, a simple, sensitive and efficient analytical method was developed and validated for the determination of 11 fungicides in grape, potato, rice, corn, wheat and soybean using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The fungicides were extracted using acetonitrile, and then the extracts were cleaned up using primary secondary amine (PSA), octadecylsilane (C18) and graphitized carbon black (GCB). Method validation displayed acceptable linearities for all pesticides (R2 greater than 0.99). The calculated limits of detection and quantification were 1 µg kg-1 and 10 µg kg-1 in different matrices, respectively. It was necessary to employ matrix-matched standards for correct quantification of these fungicides in all matrices. Acceptable recoveries (75.7-104.2%) were obtained for all the target compounds with good intra-day and inter-day precisions (RSD ≤ 11.9%). The results indicated that the method is reliable for detecting these fungicides in various foods.

Method development and validation of ten pyrethroid insecticides in edible mushrooms by Modified QuEChERS and gas chromatography-tandem mass spectrometry.

A method for simultaneous determination of ten pyrethroid insecticides residues in edible mushrooms was developed. The samples were pretreated by a quick, easy, cheap, effective, rugged (QuEChERS) method. The ten pyrethroid insecticides were extracted from six kinds of edible mushrooms using acetonitrile and subsequently cleaned up by octadecylsilane (C18) or primary secondary amine (PSA). Instrumental analysis was completed in 16 min using gas chromatography-tandem mass spectrometry (GC-MS/MS). The overall average recoveries in the six kinds of edible mushrooms at three levels (10, 100 and 1000 µg kg-1) ranged from 72.8% to 103.6%. The intraday and interday relative standard deviations (RSD) were lower than 13.0%. The quantification limits were below 5.57 µg kg-1 in different matrices. The results demonstrated that the method is convenient for the quick detection of pyrethroid insecticides in edible mushrooms.

Mechanisms of synergistic neurotoxicity induced by two high risk pesticide residues - Chlorpyrifos and Carbofuran via oxidative stress.

Multi-component pesticide residues, especially pesticide residues with synergistic toxicity, are a serious threat to food safety. With risk assessment, we found that Chlorpyrifos (CPF) and Carbofuran (CBF) are 2 pesticide residues with highest risk for Actinidia chinensis planch. The results showed CPF and CBF have a synergistic neurotoxicity on neural cell SK-N-SH. The toxicity was partly depending on oxidative stress (OS) and had effects on cell apoptosis and cell cycle arrest. Furthermore, the toxicity remained on long-term low-dose condition.

Transcriptome analysis reveals the effect of pre-harvest CPPU treatment on the volatile compounds emitted by kiwifruit stored at room temperature.

Kiwifruits are rich in nutrients beneficial to humans. Because forchlorfenuron (CPPU)-treatment after full bloom can enlarge fruit size, and significantly increase the income of farmers, it has been extensively used. However, CPPU might also influence fruit sugar and acid content, and storage performance. This study analyzed the differences in volatile emissions between CPPU-treated and water-treated kiwifruits after two, four, six, or eight days of storage, and differential gene expression related to these compounds using high-throughput sequencing. The number of volatile compounds was relatively high at the first two days of storage for both treated and control fruits, decreased in the following days, and increased again, although less significantly in CPPU-treated than in control fruits. Aldehydes in the control and treated groups showed a trend of stability vs. down-regulation, alcohols or terpenes showed high-low-high vs. down-regulation, and esters showed up-regulation vs. high-low-high, respectively. Only 60.12-66.68% of the genes obtained were mapped and 3370 new genes were annotated. Genes related to terpene biosynthesis were enriched, and, in CPPU-treated fruits, several genes related to hormone signal transduction were found in aldehydes, alcohols, and terpenes biosynthetic pathways. Although CPPU might influence the expression of genes encoding the core complex proteins in photosynthesis, its relationship with terpene synthesis is still unclear. Our results provided resources for the genetic annotation of kiwifruits, and revealed the impact of CPPU on the metabolism of their volatile compounds, laying the theoretical foundation for investigating the use of molecular techniques to inhibit the CPPU-related reduction of fruit quality.

Cumulative risk assessment of the exposure to pyrethroids through fruits consumption in China - Based on a 3-year investigation.

In the present study, the long-term and short-term cumulative risks of pyrethroids exposured for the Chinese general population and children through fruits consumption were evaluated. A total of 1450 fruit samples and seven pyrethroids were included based on the pesticide residues monitoring programme of China from 2013 to 2015. The exposure was estimated using both deterministic approach and semi-probabilistic model for comparison. The hazard index approach was used to assess cumulative risk. 26% of samples contained pyrethroid residues with concentrations ranged from 0.0050 mg/kg to 1.2 mg/kg, of which 30% simultaneously with 2-4 mixture residues. Results demonstrated that the cumulative health risks were extremely low for both general population and children (1-6 years old) of China in the long term. Acute risk estimations calculated by deterministic method were several or many times overestimated than the results based on semi-probabilistic method. Acute cumulative exposure of children to pyrethroid compounds in 0.76% samples were exceeded 1 in worst case scenario. More detailed assessments with adequate data in the future use probabilistic method is expected to reduce the uncertainties of cumulative dietary exposure.