Dissipation of six fungicides in greenhouse-grown tomatoes with processing and health risk

Ethylene-MPK8-ERF.C1-PR module confers resistance against Botrytis cinerea in tomato fruit without compromising ripening

The plant hormone ethylene plays a critical role in fruit defense against Botrytis cinerea attack, but the underlying mechanisms remain poorly understood. Here, we showed that ethylene response factor SlERF.C1 acts as a key regulator to trigger the ethylene-mediated defense against B. cinerea in tomato fruits without compromising ripening. Knockout of SlERF.C1 increased fruit susceptibility to B. cinerea with no effect on ripening process, while overexpression enhanced resistance. RNA-Seq, transactivation assays, EMSA and ChIP-qPCR results indicated that SlERF.C1 activated the transcription of PR genes by binding to their promoters. Moreover, SlERF.C1 interacted with the mitogen-activated protein kinase SlMPK8 which allowed SlMPK8 to phosphorylate SlERF.C1 at the Ser174 residue and increases its transcriptional activity. Knocking out of SlMPK8 increased fruit susceptibility to B. cinerea, whereas overexpression enhanced resistance without affecting ripening. Furthermore, genetic crosses between SlMPK8-KO and SlERF.C1-OE lines reduced the resistance to B. cinerea attack in SlERF.C1-OE fruits. In addition, B. cinerea infection induced ethylene production which in turn triggered SlMPK8 transcription and enhanced the phosphorylation of SlERF.C1. Overall, our findings reveal the regulatory mechanism of the 'Ethylene-MPK8-ERF.C1-PR' module in resistance against B. cinerea and provide new insight into the manipulation of gray mold disease in fruits.

The pivotal ripening gene SlDML2 participates in regulating disease resistance in tomato

Fruit ripening and disease resistance are two essential biological processes for quality formation and maintenance. DNA methylation, in the form of 5-methylcytosine (5mC), has been elucidated to modulate fruit ripening, but its role in regulating fruit disease resistance remains poorly understood. In this study, we show that mutation of SlDML2, the DNA demethylase gene essential for fruit ripening, affects multiple developmental processes of tomato besides fruit ripening, including seed germination, leaf length and width and flower branching. Intriguingly, loss of SlDML2 function decreased the resistance of tomato fruits against the necrotrophic fungal pathogen Botrytis cinerea. Comparative transcriptomic analysis revealed an obvious transcriptome reprogramming caused by SlDML2 mutation during B. cinerea invasion. Among the thousands of differentially expressed genes, SlβCA3 encoding a β-carbonic anhydrase and SlFAD3 encoding a ω-3 fatty acid desaturase were demonstrated to be transcriptionally activated by SlDML2-mediated DNA demethylation and positively regulate tomato resistance to B. cinerea probably in the same genetic pathway with SlDML2. We further show that the pericarp tissue surrounding B. cinerea infection exhibited a delay in ripening with singnificant decrease in expression of ripening genes that are targeted by SlDML2 and increase in expression of SlβCA3 and SlFAD3. Taken together, our results uncover an essential layer of gene regulation mediated by DNA methylation upon B. cinerea infection and raise the possible that the DNA demethylase gene SlDML2, as a multifunctional gene, participates in modulating the trade-off between fruit ripening and disease resistance.

Dissipation, Processing Factors and Dietary Exposure Assessment of Myclobutanil in Tomato

Myclobutanil residue poses a potential threat to consumers' health. This work aims to investigate the degradation behavior, residue levels, processing factors (PFs) and dietary risk of myclobutanil in tomato. Myclobutanil was analyzed using a modified quick, easy, cheap, effective, rugged, safe (QuEChERS) method combined with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS), and average recoveries ranged from 82% to 102% with relative standard deviations RSDs ≤ 9.1%. After spraying myclobutanil miscible oil under field conditions, the initial concentration of myclobutanil was 0.055 mg/kg, and its dissipation followed the first-order kinetics equation with a half-life of 2.88 days. Myclobutanil was mainly present in the tomato skin, and its concentration was about four times that in the whole tomato. The initial concentration of myclobutanil in raw tomato was 0.100 mg/kg. After washing, peeling, homogenization, simmering and canning, the residual level of myclobutanil decreased to 0.067 mg/kg, 0.023 mg/kg, 0.013 mg/kg, 0.044 mg/kg and 0.041 mg/kg, respectively. Although the procedure of simmering led to an increase in myclobutanil concentration, the PFs were all less than 1 in the whole process, showing that the processing procedure significantly decreased the residual level of myclobutanil canned tomato paste in comparison with the raw agricultural commodity. Washing, peeling, and homogenization played critical roles in reducing pesticide residues. The residues of myclobutanil during the processing of tomato pose low dietary exposure risks to consumers in China, which were acceptable. However, the acute and chronic risk quotient for children revealed that it was necessary to monitor the dietary exposure of pesticide residues for children closely.

Pesticide Residues and Effect of Household Processing in Commonly Consumed Vegetables in Jimma Zone, Southwest Ethiopia

The long-term and indiscriminate use of pesticides has resulted in serious health effects. Aside from that, developing countries do not have any monitoring systems in place to prevent the consumption of high levels of pesticides in foods. Therefore, this study aimed to determine pesticide residues and the effect of processing in commonly consumed vegetables in the southwestern part of Ethiopia. In total, 12 samples of 1 kg of each type of vegetable were collected from selected markets. Moreover, as a solution to pesticide residue problems in vegetables, the effect of different processing methods such as washing, peeling, boiling, and their cumulative effect was studied. In the analytical procedure, the modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction with florisil as a cleanup sorbent was used and the identification of pesticides was done by using gas chromatography with an electron capture detector (GC-ECD). The parent p,p'-DDT was detected at a concentration of 0.015 mg/kg in potato samples from the Serbo market and a concentration of 0.516, 0.232, 0.174, and 1.512 mg/kg in Merkato, Kochi, Serbo, and Shebe onion samples, respectively. P`p-DDT is detected at a high concentration compared to its metabolites (p,p'-DDE and p,p'-DDD), which is an indication of recent use. DDT and its metabolites, other organochlorines (lindane, γ-chlordane, dimethachlor, and heptachlor), and pyrethroids (cypermethrin and deltamethrin) exceeded the recommended limits by FAO and WHO in multiple samples of potato, onion, and cabbage. The processing result showed that washing, boiling, and the combination of the two revealed a 100% reduction in o,p'-DDT, and p,p'-DDT pesticides detected in cabbage. In conclusion, multiple residues were detected in the three vegetables studied, indicating that pesticides were applied intensively. Pesticide levels were reduced by home processing procedures, which is important for consumer safety.

Effects of Household Processing on Residues of the Chiral Fungicide Mandipropamid in Four Common Vegetables

The study aimed to detect the content of mandipropamid enantiomers in unprocessed and processed tomato, cucumber, Chinese cabbage, and cowpea samples and assess the health risks to Chinese consumers. Data showed that washing and soaking with an acidic solution reduced the mandipropamid residue from vegetable samples by 54.1-82.2%. The pickling process resulted in a 6.2-65.2% loss of mandipropamid from cucumber, Chinese cabbage, and cowpea samples. Peeling and juicing were the best removing techniques for mandipropamid residues in tomato and cucumber (removal rate (RR) value > 91%), and cooking for 5 min could effectively reduce the levels of mandipropamid in Chinese cabbage and cowpea (RR values of 81.4-99.7%). The values of processing factor for the processed vegetable samples are all less than one. No significant enantioselectivity of mandipropamid was found in the vegetables during processing. Health risk data showed that samples of four types of mandipropamid-contaminated vegetables were safe for consumption after processing.

Jasmonate increases terpene synthase expression, leading to strawberry resistance to Botrytis cinerea infection

Jasmonate induced FaTPS1 to produce terpene, and overexpression FaTPS1 led to fruit resistant against B. cinerea infection, FaMYC2 induced FaTPS1 by binding to its promoter that downstream of jasmonate. Jasmonic acid (JA) and its derivatives are associated with plant defence responses against pathogenic organisms. In the present study, a total of 10,631 differentially expressed genes, 239 differentially expressed proteins, and 229 differential metabolites were screened and found to be mainly involved in pathogen perception, hormone biosynthesis and signal transduction, photosynthesis, and secondary metabolism. In strawberry fruits, methyl jasmonate (MeJA) induced FaTPS1 expression and quickly increased the terpene content. Furthermore, FaTPS1 overexpression increased the emission of sesquiterpenes, especially germacrene D, and improved strawberry resistance against Botrytis cinerea infection, although the knockdown of FaTPS1 increased its susceptibility to the same pathogen. Using a yeast one-hybrid assay and transient expression analysis, we demonstrated that FaMYC2 can bind to the G-box element in the promoter region of FaTPS1, thus inducing FaTPS1 expression. MeJA also stimulated FaMYC2 expression and regulated downstream signalling cascades. Moreover, we presented a possible model of the new signalling pathway of MeJA-mediated strawberry resistance to B. cinerea.

The research progress in and perspective of potential fungicides: Succinate dehydrogenase inhibitors

Succinate dehydrogenase inhibitors (SDHIs) have become one of the fastest growing classes of new fungicides since entering the market, and have attracted increasing attention as a result of their unique structure, high activity and broad fungicidal spectrum. The mechanism of SDHIs is to inhibit the activity of succinate dehydrogenase, thereby affecting mitochondrial respiration and ultimately killing pathogenic fungi. At present, they have become popular varieties researched and developed by major pesticide companies in the world. In the review, we focused on the mechanism, the history, the representative varieties, structure-activity relationship and resistance of SDHIs. Finally, the potential directions for the development of SDHIs were discussed. It is hoped that this review can strengthen the individuals' understanding of SDHIs and provide some inspiration for the development of new fungicides.

Analysis of Multi-Pesticide Residues and Dietary Risk Assessment in Fresh Tomatoes (Lycopersicum esculentum) from Local Supermarkets of the Metropolitan Region, Chile

In recent years, the official authorities in Chile have reported transgressions in the maximum residue levels of pesticides in fresh vegetables. There is no official information about traceability, pesticide levels, and potential health risks. The aim of this study was to analyse pesticide residues and their corresponding dietary risk assessments in tomatoes from supermarkets in the Metropolitan Region. Pesticides were extracted using the Quick, Easy, Cheap, Effective, Rugged and Safe, QuEChERS method, and their concentrations were determined by using chromatography with HPLC-FL/UV and GC-MS/ECD/NPD, following the Analytical Quality Control and Method Validation Procedures for Pesticides Residues Analysis in Food and Feed, SANTE guide and ISO 17025:2017 standard. In addition, a dietary risk assessment was carried out by comparing Chilean data to international references. The results reported that 9% of the samples had pesticide residue levels above the maximum residue levels permitted in Chile. All the scenarios evaluated revealed the highest estimated daily intake and hazard quotients for methamidophos and chlorpyrifos. Both the active substances used were acetylcholinesterase inhibitors and were neurotoxic under chronic risk assessment. The results showed the highest chronic hazard index in the Chilean scenario for all age groups and genders. The evidence obtained revealed that methamidophos, methomyl, and chlorpyrifos should be restricted for their use in Chilean agriculture.

Dissipation kinetics and processing behavior of boscalid and pyraclostrobin in greenhouse dill plant (Anethum graveolens L.) and soil

BACKGROUND

Determining the environmental behavior and fate of chemical compounds during technological processing of plants is a task of great significance nowadays. However, the current knowledge is still incomplete for unique herbal matrices belonging to minor crops. The research in this article presents, for the first time, the dissipation kinetics and processing behavior of carboxamide boscalid (BOS) and stobilurin pyraclostrobin (PYR) fungicides during glasshouse dill (Anethum graveolens L.) cultivation.

RESULTS

The half-lives (t_1/2 ) of BOS and PYR after application at the recommended and double dosage were in the range: 1.62-2.01 days in plant and 2.08-4.85 days in soil, respectively. The processing behavior in dill was estimated after washing, hot air drying and drying in sunlight without/with pretreatment. Processing factors (PFs) were above 1 after drying (PF = 1.24-1.39 hot air; PF = 1.15-1.28 sunlight) and below this value when the washing step was applied (PF = 0.31-0.42 hot air; PF = 0.21-0.34 sunlight), indicating the highest effectiveness of reduction, up to 73% BOS and 79% PYR.

CONCLUSION

BOS/PYR residues at pre-harvest intervals after both doses were below European Union (EU) maximum residue limits (MRLs). The highest effectiveness was noted for drying carried out with the washing step, which has a great influence on the concentration of residues in the final product. The findings can supplement PF databases not set for minor crops and can be used to establish MRLs and determine human exposures more accurately in risk assessment studies. © 2021 Society of Chemical Industry.

Evaluation of energy use and carbon dioxide emissions from the consumption of fossil fuels and agricultural chemicals for paste tomato cultivation in the Bursa region of Turkey

This study was aimed to determine the fossil fuel consumption, energy use, and carbon dioxide (CO₂) emissions in per unit production area (ha) considering the petroleum products (PP) directly used and the chemical fertilizers and pesticides for the cultivation of paste tomatoes in open-field conditions in Bursa region of Turkey. The primary data of the study consisted of data collected by making face-to-face surveys with the producers of paste tomatoes in the Bursa region. The direct energy inputs and CO₂ emissions related to diesel fuel and lubricant oil consumptions of engines of agricultural tractors for cultivation operations and the indirect energy inputs and CO₂ emissions related to the manufacturing of chemical fertilizers and plant growth regulators used for plant nutrition and pesticides used for plant protection were determined for paste tomato cultivation. A total of 288.6 L diesel fuel and 0.067 L lubrication oil are consumed per hectare when using tools and machinery in paste tomato production. A total of 408 kg of chemical fertilizers and 15.5 kg of pesticides are used per hectare in paste tomato production in the Bursa region of Turkey. A total of 2343.45 MJ/ha and 2700.5 MJ/ha indirect energy is used in the application of chemical fertilizers and pesticides, respectively. A total of 792.43 kg and 0.189 kg CO₂ is released as a result of diesel fuel and lubricant oil consumptions. For the production of one kilogram of paste tomato, 2.68 grams (g) diesel fuel and lubricating oil, 175.02 kilojoules (kJ) of energy is consumed, and 15.88 g CO₂ is released in the Bursa region of Turkey.

Effect of decocting on the pesticide residues in Paeoniae radix lactiflora and corresponding exposure risk assessment

Numerous natural preparations in traditional Chinese medicine are prepared as decoctions. Processing factors (PFs) comparing the levels of pesticide residues in decoctions to those in the corresponding unprocessed products should be considered in exposure assessments. Thus, this study determined the residue levels of six pesticides (chlorpyrifos, phoxim, imidacloprid, thiamethoxam, fenpropathrin, and emamectin benzoate), as well as 3,5,6-trichloropyridinol, the primary metabolite of chlorpyrifos, and clothianidin, the main metabolite of thiamethoxam in Baishao, Paeoniae radix lactiflora (Fam. Ranunculaceae). The results showed that significant time-response effects were present for the release of pesticides from P. radix. The PFs calculated were < 1, indicating a significant reduction in pesticide residues after TCM processing. The water solubility and partition coefficient values of the pesticides may have played a basic role in the dissipation of the residues during the TCM decocting process. A risk assessment based on the hazard quotient with PFs revealed that exposure to pesticide residues in P. radix was far below the levels that might pose a health risk. In conclusion, the results presented here are of theoretical and practical value for the safety evaluation of TCMs.

Dissipation, accumulation and risk assessment of fungicides after repeated spraying on greenhouse strawberry

Repeated spraying of fungicides is a common phenomenon in greenhouse strawberry cultivation, and the continuous harvest of strawberries makes them prone to contamination by accumulated fungicides. Despite this, very few residue safety assessments of fungicides on greenhouse strawberries are conducted after repeated spraying of fungicides, and no research exists on fungicide dissipation and accumulation mechanism. Therefore, the present study investigated the dissipation and accumulation of four fungicides (pyraclostrobin, pyrimethanil, procymidone, and cyprodinil) after two typical repeated sprayings (a single fungicide repeated spraying and two fungicides sprayed using an alternate repeated technique). The half-life of pyraclostrobin after three single repeated sprayings was 18 d; however, its average half-life decreased to 9 d after alternate repeated spraying with cyprodinil. The shortened half-life may be attributed to cyprodinil water solution washing during alternate repeated spraying. The other three fungicides showed similar half-lives after single and alternate repeated spraying, following the order of cyprodinil (12 d and 10 d) > procymidone (11 d and 10 d) > pyrimethanil (6 d and 7 d). The octanol-water partition coefficient was a more efficient indicator of the half-life order of the fungicides than vapor pressure and water solubility. Pyraclostrobin showed the highest deposition efficiency but negligible residue accumulation; further, the residue accumulation of the four fungicides followed the order of procymidone > cyprodinil > pyrimethanil > pyraclostrobin after both single and alternate repeated spraying. A safety assessment demonstrated that the maximum number of times cyprodinil could be sprayed after single spraying was one; however, this number doubled after alternate spraying. The risk of exceeding the maximum residue limits of the fungicides on greenhouse strawberries decreased; however, the combined dietary risks of fungicides after alternate spraying might be high. Alternate repeated spraying of procymidone and pyrimethanil may be the optimal repeated spraying combination for greenhouse strawberries.

Evaluation of boscalid toxicity on Daphnia magna by using antioxidant enzyme activities, the expression of genes related to antioxidant and detoxification systems, and life-history parameters

Boscalid is a succinate dehydrogenase inhibitor fungicide commonly used to control a range of plant pathogens. Although it is one of the most common fungicides in the aquatic environment, the potential adverse effects of boscalid on freshwater invertebrates still remain unclear. This study aimed to evaluate the toxicity of boscalid on Daphnia magna (D. magna) and provide new information to assess the eco-toxicity of the boscalid on aquatic invertebrates. The effects of boscalid on malondialdehyde (MDA) level, activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and the mRNA level of genes associated with antioxidant system (sod, cat, and gst) and detoxification (cytochrome P450 4 (cyp4) and nuclear respiratory factor 1 (nrf1)) were determined after 48 h treatment. The effect of boscalid on reproduction and development of D. magna was evaluated by a 21-d-chronic toxicity test. Boscalid dose-dependently altered activities of SOD, CAT, and GST and led to lipid peroxidation during acute exposure in D. magna. Exposure to 5 and 10 mg/L boscalid also significantly decreased gene expression of sod, gst, cyp4 and nrf1 but increased cat gene expression. Furthermore, chronic toxicity results showed that exposure to boscalid decreased molting frequency, number of neonates per Daphnia, and the number of broods per female as compared to the control groups. The above results indicated that boscalid had significant negative impacts on D. magna, and information present here helps to evaluate the eco-toxicity caused by boscalid on aquatic invertebrates.

Killer Yeasts for the Biological Control of Postharvest Fungal Crop Diseases

Every year and all over the world the fungal decay of fresh fruit and vegetables frequently generates substantial economic losses. Synthetic fungicides, traditionally used to efficiently combat the putrefactive agents, emerged, however, as the cause of environmental and human health issues. Given the need to seek for alternatives, several biological approaches were followed, among which those with killer yeasts stand out. Here, after the elaboration of the complex of problems, we explain the hitherto known yeast killer mechanisms and present the implementation of yeasts displaying such phenotype in biocontrol strategies for pre- or postharvest treatments to be aimed at combating postharvest fungal decay in numerous agricultural products.

Photolysis and TiO2 Photocatalytic Treatment under UVC/VUV Irradiation for Simultaneous Degradation of Pesticides and Microorganisms

Efficiencies of various treatments for UVC photolysis (ultraviolet light-C at 254 nm), VUV photolysis (vacuum ultraviolet light at 254 nm and 185 nm), UVC-assisted titanium dioxide photocatalysis (UVC-TiO2), and VUV-assisted titanium dioxide photocatalysis (VUV-TiO2) were investigated for the degradation of pesticides including pyraclostrobin, boscalid, fludioxonil, and azoxystrobin and inactivation of microorganisms Escherichia coli K12 as a surrogate for E. coli O157:H7 and Saccharomyces cerevisiae in aqueous solutions and on the surface of fresh cut carrots. The degradation efficiencies of VUV were higher than for UVC on pesticides in aqueous solutions. However, there was no significant difference between degradation efficiencies for UVC and UVC-TiO2 treatments, and between VUV and VUV-TiO2 treatments. UVC, VUV, UVC-TiO2, and VUV-TiO2 showed similar inactivation effects against E. coli K12 and S. cerevisiae in aqueous solutions. The combined use of UVC and VUV treatments (combined UV) and combined use of UVC-TiO2 and VUV-TiO2 treatments (combined UV-TiO2) showed higher efficiencies (72–94% removal) for the removal of residual pesticides on fresh cut carrots than bubble water washing (53–73% removal). However, there was no significant difference in removal efficiency between combined UV and combined UV-TiO2 treatments. For E. coli K12 and S. cerevisiae on fresh cut carrots, the combined UV-TiO2 treatment (1.5 log and 1.6 log reduction, respectively) showed slightly higher inactivation effects than combined UV (1.3 log and 1.2 log reduction, respectively). Photolysis and TiO2 photocatalytic treatments under UV irradiation, including VUV as a light source, showed potential for the simultaneous degradation of pesticides and microorganisms as a non-chemical and residue-free technique for surface disinfection of fresh produce.

Removal residues of pesticides in apricot, peach and orange processed and dietary exposure assessment

The effects of the industrial processing are evaluated of the removal of 16 pesticide residues in canned apricots and peaches and in orange juice. A method of multi-residual extraction that uses QuEChERS and liquid chromatography in tandem with triple quadrupole mass spectrometry was used. The method shows good linearity for the 16 pesticides studied (R2 > 0.999); it is accurate and precise (recoveries of 87-115%, relative standard deviation <8.0%). The processing factors are <0.6, indicating that all the processes significantly reduce the residue levels (spinosad, thiacloprid, pyridaben, bupirimate, flusilazole, triflumizole, flonicamid, imidacloprid, lambda-cyhalothrin, cyproconazole, fludioxinil and cyprodinil, abamectin, chlorpyrifos-methyl, hexythiazox and metalaxyl) initially present in the raw fruits and very significantly during washing/cutting, squeezing and hot pack canning (>55% loss). The risk quotient (EDI/ADI ratio) for canned foods is below 100, indicating that the potential consumer risk for the pesticides studied is practically negligent for human health.

Metabolic profile and behavior of clethodim and spirotetramat in herbs during plant growth and processing under controlled conditions

Herbs may contain pesticide residues which are an important discriminator of food security and food quality. The challenge of the research was to assess the fate of the herbicide clethodim (CLE) and the insecticide spirotetramat (SPI) applied in herbs (BBCH 11-21) during herb growth and processing under controlled greenhouse trial conditions. The metabolic profile of CLE and SPI and their degradation products in basil (Ocimum basilicum L.), peppermint (Mentha × piperita L.) and sage (Salvia officinalis L.) was also presented. The half-lives of CLE and SPI in herbs were 1.10-1.56 days and 0.51-0.83 days, respectively. The terminal residues of SPI (SPI-enol, SPI-ketohydroxy, SPI-monohydroxy and SPI-enol-glucoside) and CLE (CLE-sulfone and CLE-sulfoxide) in herbal matrices were measured below EU maximum residue limits. In this paper, we aimed to assess the impact of washing and dehydratation pretreatment and calculated processing factors (PFs) which can be applied to more accurate food safety assessments. The PF values of CLE and SPI after drying prior washing was below 1 indicating reduction of initial residues. Drying process without washing demonstrated increases of SPI concentrations (PF up to 1.50). The lowest PFs were obtained when raw herbal plants were washed before drying showing almost complete degradation of parent compound (93-99%).

Dissipation pattern and residual levels of boscalid in cucumber and soil using liquid chromatography-tandem mass spectrometry

To stipulate the rationale of spraying doses and to determine the safe interval period of boscalid suspension concentrate (SC), the degradation dynamics and residual levels were investigated in cucumber and soil using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Field trials were conducted according to Chinese Guideline on pesticide residue trials. Following application, the degradation kinetics was best ascribed to first-order kinetic models with half-life of 2.67-9.90 d in cucumber. Spraying boscalid SC at 1.5-fold the recommended dosage yield terminal residues, which are clearly lower than the maximum residue limit (MRL) established by China (MRL =5 mg.kg^-1) in cucumber. At variance, the dissipation dynamics in soil did not fit to first-order kinetics and the half-life was more than 17 days, the finding which denotes that the degradation behavior of boscalid in soil proceeds slowly. It has therefore been shown that boscalid is safe for use on cucumbers under the recommended dosage.

Effects of processing and storage on pesticide residues in foods

Pesticides are chemicals frequently used in agriculture to obtain maximum yield and improve product quality. Thousands of active ingredients and formulations of different pesticides are commercially available. Besides their advantages, a major disadvantage of pesticides is their residues, even though strict maximum residue limits have been set for each pesticide and permitted agricultural commodity. Permanence of pesticide residues on agricultural products depends on several factors such as the properties of pesticide, formulation, and applied concentration. Light, temperature, plant morphology, and plant growth factors are also effective in determining permanence. Degradation effects of the processing treatments rely on the dissolution of pesticides in the surrounding atmosphere, hydrolysis, microbial degradation, oxidation, penetration, and photo-degradation. Various steps applied during food processing, such as washing with water or other aqueous solutions, peeling, chopping, pickling, heat treatments, and processes such as drying, canning, fruit juice and concentrate production, malt, beer and wine production, oil production, and storage have certain effects on the presence of pesticide residues as well. Only washing with water can remove pesticide residue up to 100%, depending on the location of residue, residence time on food, water solubility of residue, washing temperature, and agents used to increase effectiveness. Besides washing, skin removal or peeling is one of the most effective treatments for residue removal, especially on non-systemic pesticides. During cooking, residues might be evaporated or hydrolyzed. Effects of storage temperature on reduction are related to volatilization, penetration, metabolism of pesticide, moisture content, and microbial growth, if any. In refrigerated or frozen storage, residues are stable or degrade slowly. Drying may increase the residue content because of the concentration, but in sun-drying reduction may occur because of photo-degradation. Clarification and filtration may eliminate residues retained in suspended particles. The degradation product, however, may be more toxic than the initial compound in some cases.

Effect of storage, washing, and cooking on the stability of five pesticides in edible fungi of Agaricus bisporus: A degradation kinetic study

Pesticide residue in food products is one of the most important global health challenges. The current study sought to investigate the changes in pesticides residue levels in Agaricus bisporus under different storage conditions and during washing and cooking. Pesticides analysis was performed using gas chromatography/mass spectrometry (GC-MS). The results showed that the half-life (t1/2) of all of the studied pesticides stored at room temperature was lower than refrigerator and freezer temperature. In addition, the greatest reduction of diazinon, malathion, permethrin, propargite, and fenpropathrin was found at a pH of 12, 2, 12, 7, and 9, respectively. Although sodium chloride had no effective impact on pesticide reduction during the same washing times, the removal of pesticides increased as washing time increased. Further, the reduction of pesticides was time-dependent during the boiling, microwaving, and frying processes. Based on these findings, the stability of insecticides, such as permethrin, malathion, and diazinon, was lower than acaricides, including propargite and fenpropathrin, in various techniques. Therefore, the use of washing solutions with an appropriate pH as well as increased cooking time may reduce the risk of pesticide exposure.

Biotransformation of chlorothalonil by strain Stenotrophomonas acidaminiphila BJ1 isolated from farmland soil

Chlorothalonil is a widely used fungicide, but the contamination of soil and water environments by this chemical causes potential threats to biodiversity. Given the metabolic potential of soil microorganisms, there is a need for developing microbiological approaches to degrade persistent compounds, such as chlorothalonil, in contaminated sites. Here in this study, we isolated a bacterial strain (namely, BJ1) capable of degrading chlorothalonil from a chlorothalonil-contaminated farmland soil in the Shandong Province, China. Using 16S rDNA gene sequencing, morphological and biological characteristics, we identified the strain BJ1 as Stenotrophomonas acidaminiphila. The strain BJ1 uses chlorothalonil as a sole carbon source. At initial concentrations of 50, 100, 200 and 300 mg l-1, it degraded 91.5%, 89.4%, 86.5% and 83.5% of chlorothalonil after 96 h of inoculation under optimum conditions (30°C and pH 7.0). Two metabolites, methyl-2,5,6-trichloro-3-cyano-4-methoxy-benzoate and methyl-3-cyano-2,4,5,6-tetrachlorobenzoate, were detected and identified based on HPLC-MS analysis, which suggests that the strain BJ1 metabolized chlorothalonil through the hydroxylation of chloro-group and hydration of cyano-group. The results of this study highlight the great potential for this bacterium to be used in chlorothalonil pollution remediation.

Dissipation Behavior of Three Pesticides in Prickly Pear (Opuntia ficus-indica (L.) Mill.) Pads in Morelos, Mexico

The dissipation of three field-applied pesticides (chlorothalonil, chlorpyrifos, and malathion), on cultivated prickly pear (Opuntia ficus-indica (L.) Mill.) pads was studied. The extraction of pesticides was carried out using the European quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction technique and detection was carried out using tandem liquid chromatography with mass spectrometry. At harvest, 15 days after application, pesticide dissipation was below the level of detectability. Dissipation curves for prickly pear pads fit to a first-order kinetic equation. Two initial concentration levels were used for each pesticide. The approximate dissipation time for all pesticides studied was similar (10 days) and the half-life time was around six days. Final concentrations for the three pesticides were below the reference maximum residue level (MRL) (0.01 mg/kg), which suggests that these products can be applied safely in the commercial production of prickly pear pads at the established concentrations.

The dissipation of cyazofamid and its main metabolite CCIM during tomato growth and tomato paste making process

In several studies focused on the residues of cyazofamid and its main metabolite 4-chloro-5-p-tolylimidazole-2-carbonitrile (CCIM) on tomato where it is widely used, CCIM has been shown to have higher acute toxicity than cyazofamid, and this is crucial to evaluate the potential food risk of cyazofamid and CCIM. In this study, the dissipation of cyazofamid and CCIM during tomato growth and tomato paste making process were assessed. The targeted compounds cyazofamid and CCIM were determined by LC-MS/MS. The results indicated that the half-life of cyazofamid was 4.6 days after applying in the field, and the maximum value of CCIM was 0.08 mg/kg at 3 days after the last application of cyazofamid, then gradually decreased. In addition, the concentrations of cyazofamid and CCIM were affected by different processing steps including washing, peeling, homogenisation, simmering, and sterilisation. Results showed that the mean losses of cyazofamid and CCIM were 92.3% and 75.2% after washing and peeling. The Processing Factor (PF) values were all less than 1. Especially for peeling, the PFs of cyazofamid and CCIM were 0.12 and 0.04, respectively.

Degradation of triadimefon and residue levels of metabolite triadimenol: tracing rapeseed from harvesting and storage to household oil processing

BACKGROUND

Triadimefon is a fungicide used in agriculture to control fungal diseases such as sclerotinia sclerotiorum.

RESULTS

In field trials, rape plants were sprayed with triadimefon at three different dosages during the flowering period. The degradation of triadimefon and the residue levels of its metabolite, triadimenol, in rapeseed obtained from harvesting, storage, and household oil processing were traced and evaluated. The pesticides were determined by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) at each processing step. Triadimefon degraded completely and only its metabolite, triadimenol, was detected in rapeseed after harvesting. The stability of triadimenol in rapeseed was studied at weekly storage intervals, from 0 to 7 weeks at ambient temperature (25 °C) and freezing temperature (-20 °C), respectively. Storage temperature had an important influence on the residue levels of triadimenol. The processing factor (PF) was defined as the ratio of pesticide residue levels in rapeseed to rapeseed oil levels during household oil processing. The average PF of triadimenol was about 0.96 for a hot pressing technique and 0.88 for a cold pressing technique.

CONCLUSION

Different storage conditions and food processing could reduce the pesticide level to a greater or lesser extent. However, it is not easy to eliminate or significantly weaken triadimenol once triadimefon has degraded completely. © 2018 Society of Chemical Industry.

Analysis of exposure to pesticide residues from Traditional Chinese Medicine

The safety of Traditional Chinese Medicine (TCM) is of concern worldwide. Herein, Paeoniae Radix Alba, Chaenomelis Fructus and Moutan Cortex, representing three medicinal components, were subjected to toxicological analysis to investigate possible pesticide contamination. Exposure using a point estimate model identified 47 residues that were simultaneously validated by the QuEChERS-UPLC-MS/MS method, which is sufficiently reliable for measuring residue concentrations. Of the 313 samples tested, 94.57% contained pesticide residues, with concentrations ranging from 0.10 to 1199.84 μg kg^-1, of which >83.17% contained 4-15 different residues. Carbendazim was the most frequently detected pesticide (>85%), and procymidone, pendimethalin and phoxim were also abundant (median concentration = 15.33-623.12 μg kg^-1). Risk assessment based on the hazard quotient/hazard index (HQ/HI) approach revealed that exposure to pesticide residues in all three TCMs (95th percentile) were far below levels that might pose a health risk. However, insecticides contributed to cumulative exposure, especially phoxim, and worryingly, several banned pesticides were detected. The results are of theoretical and practical value for evaluating the safety TCMs, and could improve their quality and safety.

Dissipation of Pre-Harvest Pesticides on ‘Clementine’ Mandarins after Open Field Application, and Their Persistence When Stored under Conventional Postharvest Conditions

The dissipation of field-applied difenoconazole, imidacloprid, pyraclostrobin and spinosad on Clementine mandarins (Citrus clementina Hort. ex Tan.) under controlled conditions throughout the citrus production chain was assessed. At harvest, 42 days after application, the dissipation of these pesticides were 80, 92, and 48% for difenoconazole, imidacloprid, pyraclostrobin, respectively, and spinosad was below the level of detectability. At day 28 after application, spinosad was no longer detected. The model equations that best describe the dissipation curves of these pesticides on Clementine mandarins showed different patterns. Their half-life on Clementine, calculated by the best-fitted experimental data, were 19.2 day (1st-order model) for difenoconazole, 4.1 day (Root Factor (RF) 1st-order model) for imidacloprid, 39.8 day (2nd-order model) for pyraclostrobin and 5.8 day (1st-order model) for spinosad. These results are the first record of pyraclostrobin persistence on mandarins, showing a longer half-life in this matrix than those reported for any other fruit. The treated fruit were harvested and submitted to the usual postharvest treatments: first, a hypochlorite drenching was performed; as a second step, imazalil and wax were applied, and then the mandarins were stored at 4 °C. After 32 days, cold storage caused no significant effects on the residue levels of the four pesticides compared with those determined on freshly harvested mandarins. All residues were below their Codex and European Union (EU) maximum residue limit (MRL) for mandarin since the spray application day.

Effect of methyl salicylate in combination with 1-methylcyclopropene on postharvest quality and decay caused by Botrytis cinerea in tomato fruit

BACKGROUND

Postharvest diseases result in major losses in fruits. Tomato is susceptible to postharvest rot caused by Botrytis cinerea and is regarded as a good model system to study postharvest disease and quality deterioration in fruit. To develop a safe and effective technique to alleviate disease and maintain fruit quality, the effects of methyl salicylate (MeSA) and 1-methylcyclopropene (1-MCP) either separately or combined on quality and gray mold caused by B. cinerea in tomato fruit were investigated.

RESULTS

The results showed that application of MeSA (0.05 mmol L^-1 ) delayed fruit ripening and reduced gray mold. Compared with MeSA treatment, 1-MCP (0.5 µL L^-1 ) effectively delayed fruit ripening. Further, MeSA combined with 1-MCP treatment was more effective in inhibiting fungal decay during storage than MeSA treatment alone. The combined treatment not only enhanced pathogenesis-related protein 1 (PR1) expression, activities of defense enzymes and total phenolic content but also inhibited the increase in electrical conductivity and malondialdehyde content. The combined treatment was also more effective in retaining firmness, color change and titratable acidity content than MeSA treatment alone.

CONCLUSION

MeSA combined with 1-MCP treatment was a useful technique to maintain quality and alleviate gray mold in postharvest tomato fruit during storage. © 2018 Society of Chemical Industry.

Assessment of boscalid and pyraclostrobin disappearance and behavior following application of effective microorganisms on apples

The aim of this study is to assess the disappearance of boscalid (IUPAC name: 2-chloro-N-[2-(4-chlorophenyl)phenyl]pyridine-3-carboxamide) and pyraclostrobin (IUPAC name: methyl N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-N-methoxycarbamate) residues in apple fruit, and to verify whether an organic fertilizer enriched with strains of antagonistic microorganisms can reduce pesticide residue levels. Field trials were conducted in a commercial orchard on apples of the Gloster variety, during 21 days after the treatment with Bellis 38 WG and the subsequent application of Zumba Plant formulation containing Bacillus spp., Trichoderma spp. and Glomus spp. In control samples, the decrease rate of boscalid and pyraclostrobin residue levels followed an exponential function, described by formulae R_t = 0.2824e^-0.071t and R_t = 0.1176e^-0.060t, with the coefficient of determination of r² = 0.8692 and r² = 0.9268, respectively. These levels dropped to half (t_1/2) of their initial values after 9.8 and 11.5 days, respectively. The treatment with Zumba Plant resulted in a reduction in boscalid and pyraclostrobin residue levels by 52% and 41%, respectively. The results of this study are of importance for horticulture sciences and for producers of apples using plant protection products (PPPs).

Evaluation of joint effects of cyprodinil and kresoxim-methyl on zebrafish, Danio rerio

Aquatic organisms are usually exposed to a mixture of pesticides instead of individual chemicals. However, risk assessment of pesticides is traditionally based on toxicity data of individual compounds. In this study, we aimed to examine the joint toxicity of two fungicides cyprodinil (CYP) and kresoxim-methyl (KRM) to zebrafish (Danio rerio) using a systematic experimental approach. Results from 96-h semi-static test indicated that the LC₅₀ values of KRM to D. rerio at multiple life stages (embryonic, larval, juvenile and adult stages) ranged from 0.034 (0.015-0.073) to 0.61 (0.39-0.83) mg a.i. L^-1, which were higher than those of CYP ranging from 1.05 (0.88-1.52) to 4.42 (3.24-6.02) mg a.i. L^-1. Pesticide mixtures of CYP and KRM exhibited synergistic effect on embryonic zebrafish. The activities of carboxylesterase (CarE) and cytochrome P450 (Cyp450) were significantly altered in most of the individual and combined exposures compared with the control group. The expressions of seven genes (Mnsod, cyp17, crhr 2, crh, gnrhr 4, gnrhr 1 and hmgrb) were significantly altered upon exposure to combined pesticides compared with their individual pesticides. Collectively, these findings suggested joint effects should be considered in the risk assessment of pesticides and development of water quality criteria for the protection of aquatic environment.

Carbon-Based Fe₃O₄ Nanocomposites Derived from Waste Pomelo Peels for Magnetic Solid-Phase Extraction of 11 Triazole Fungicides in Fruit Samples

Carbon-based Fe₃O₄ nanocomposites (C/Fe₃O₄ NCs) were synthesized by a simple one-step hydrothermal method using waste pomelo peels as the carbon precursors. The characterization results showed that they had good structures and physicochemical properties. The prepared C/Fe₃O₄ NCs could be applied as excellent and recyclable adsorbents for magnetic solid phase extraction (MSPE) of 11 triazole fungicides in fruit samples. In the MSPE procedure, several parameters including the amount of adsorbents, extraction time, the type and volume of desorption solvent, and desorption time were optimized in detail. Under the optimized conditions, the good linearity (R² > 0.9916), the limits of detection (LOD), and quantification (LOQ) were obtained in the range of 1–100, 0.12–0.55, and 0.39–1.85 μg/kg for 11 pesticides, respectively. Lastly, the proposed MSPE method was successfully applied to analyze triazole fungicides in real apple, pear, orange, peach, and banana samples with recoveries in the range of 82.1% to 109.9% and relative standard deviations (RSDs) below 8.4%. Therefore, the C/Fe₃O₄ NCs based MSPE method has a great potential for isolating and pre-concentrating trace levels of triazole fungicides in fruits.

A study on residue levels of fungicides and insecticides applied according to the program of raspberry protection

This paper presents surveys on residue levels of fungicides and insecticides applied according to the raspberry protection program. The field trials were conducted in 2013-2014 on a plantation of raspberry of the Laszka variety dessert raspberry very popular in Poland. Laboratory samples were collected starting from a day of the first fruit picking to the end of harvest. The highest mean residue levels were found for boscalid and pyraclostrobin (2.395 mg/kg and 0.732 mg/kg, respectively), in both cases they were at a level of about 24% of their maximum residue levels (MRLs); and for cypermethrin (0.235 mg/kg; i.e. close to 50% of its MRL). The long-term dietary intakes of those substances by Polish adult consumers were also at low levels of 0.52, 0.22, and 0.04% of acceptable daily intake (ADI), respectively. Therefore, the results obtained indicated that even on day zero of picking ripe raspberries, the pesticide residues not only were well below their corresponding MRLs, but also their daily intakes did not even approach 1% of the ADI. In 2013, pesticide residues in ripe fruit evolved according to a pattern different than in a subsequent year; while in 2014 they changed at a constant exponential rate.

Successive chlorothalonil applications inhibit soil nitrification and discrepantly affect abundances of functional genes in soil nitrogen cycling

Broad-spectrum fungicide chlorothalonil (CTN) is successively applied into intensive agriculture soil. However, the impacts of successive CTN applications on soil nitrification and related microorganisms remain poorly understood. A microcosm study was conducted to reveal the effects of successive CTN applications on soil nitrification and functional genes involved in soil nitrogen (N) cycling. The CTN at the dosages of 5 mg kg^-1 dry soil (RD) and 25 mg kg^-1 dry soil (5RD) was successively applied into the test soil at 7-day intervals which resulted in the accumulations of CTN residues. After 28 days of incubation, CTN residues in the RD and 5RD treatments were 3.14 and 69.7 mg kg^-1 dry soil respectively. Net nitrification rates in the RD and 5RD treatments were lower than that obtained from the blank control (CK). Real-time PCR analysis revealed that AOA and AOB amoA gene abundances were significantly decreased by CTN applications. Moreover, CTN applications also discrepantly decreased the abundances of functional genes involved in soil denitrification, with the exception of nosZ gene. Principal component analysis further supported the observation that successive CTN applications could result in enhanced ecological toxicity.

Effervescence-assisted dispersive solid-phase extraction using ionic-liquid-modified magnetic β-cyclodextrin/attapulgite coupled with high-performance liquid chromatography for fungicide detection in honey and juice

In this study, a simple effervescence-assisted dispersive solid-phase extraction method was developed to detect fungicides in honey and juice. Most significantly, an innovative ionic-liquid-modified magnetic β-cyclodextrin/attapulgite sorbent was used because its large specific surface area enhanced the extraction capacity and also led to facile separation. A one-factor-at-a-time approach and orthogonal design were employed to optimize the experimental parameters. Under the optimized conditions, the entire extraction procedure was completed within 3 min. In addition, the calibration curves exhibited good linearity, and high enrichment factors were achieved for pure water and honey samples. For the honey samples, the extraction efficiencies for the target fungicides ranged from 77.0 to 94.3% with relative standard deviations of 2.3-5.44%. The detection and quantitation limits were in the ranges of 0.07-0.38 and 0.23-1.27 μg/L, respectively. Finally, the developed technique was successfully applied to real samples, and satisfactory results were achieved. This analytical technique is cost-effective, environmentally friendly, and time-saving.