14C-chlorpyrifos residues in tomatoes and tomato products

Impact of pesticide polarity and lipid phase dimensions on the bioaccessibility of pesticides in agricultural produce consumed with model fatty foods

For most people, the pesticide residues found on agriculture products are the main source of pesticide exposure, which may adversely influence consumer health. The potential health hazard of residual pesticides depends on the nature of the foods they are consumed with. Studies with fat-soluble vitamins and nutraceuticals have shown that their bioaccessibility depends on food matrix composition and structure. We used an in vitro method to investigate the influence of the dimensions of the lipid phase in model fatty foods (emulsified or bulk oil) on the bioaccessibility of various pesticides. Three pesticides that differed in their oil-water partition coefficients were selected: bendiocarb (log P = 1.7), parathion (log P = 3.8), and chlorpyrifos (log P = 5.3). These pesticides were mixed with tomato puree to represent pesticide-treated agricultural products. Three model foods with different oil phase dimensions were used to represent different kinds of food product: small emulsions (d32 = 0.14 μm); large emulsions (d32 = 10 μm); and, bulk oil. Our results showed that the oil droplets underwent extensive changes as they passed through the simulated gastrointestinal tract due to changes in environmental conditions, such as pH, ionic strength, bile salts, and enzyme activities. The initial rate and final amount of lipid hydrolysis decreased with increasing lipid phase dimensions. Pesticide bioaccessibility depended on both the hydrophobicity of the pesticide and the dimensions of the co-ingested lipid droplets. The least hydrophobic pesticide (bendiocarb) had a high bioaccessibility (>95%) that did not depend on lipid phase dimensions. The more hydrophobic pesticides (parathion and chlorpyrifos) has a lower bioaccessibility that increased with decreasing lipid phase dimensions. Our results demonstrate the critical role that food structure plays on the potential uptake of pesticides from agricultural products, like fruits and vegetables.

Impact of Pesticide Type and Emulsion Fat Content on the Bioaccessibility of Pesticides in Natural Products

There is interest in incorporating nanoemulsions into certain foods and beverages, including dips, dressings, drinks, spreads, and sauces, due to their potentially beneficial attributes. In particular, excipient nanoemulsions can enhance the bioavailability of nutraceuticals in fruit- and vegetable-containing products consumed with them. There is, however, potential for them to also raise the bioavailability of undesirable substances found in these products, such as pesticides. In this research, we studied the impact of excipient nanoemulsions on the bioaccessibility of pesticide-treated tomatoes. We hypothesized that the propensity for nanoemulsions to raise pesticide bioaccessibility would depend on the polarity of the pesticide molecules. Bendiocarb, parathion, and chlorpyrifos were therefore selected because they have Log P values of 1.7, 3.8, and 5.3, respectively. Nanoemulsions with different oil contents (0%, 4%, and 8%) were fabricated to study their impact on pesticide uptake. In the absence of oil, the bioaccessibility increased with increasing pesticide polarity (decreasing Log P): bendiocarb (92.9%) > parathion (16.4%) > chlorpyrifos (2.8%). Bendiocarb bioaccessibility did not depend on the oil content of the nanoemulsions, which was attributed to its relatively high water-solubility. Conversely, the bioaccessibility of the more hydrophobic pesticides (parathion and chlorpyrifos) increased with increasing oil content. For instance, for chlorpyrifos, the bioaccessibility was 2.8%, 47.0%, and 70.7% at 0%, 4%, and 8% oil content, respectively. Our findings have repercussions for the utilization of nanoemulsions as excipient foods in products that may have high levels of undesirable non-polar substances, such as pesticides.

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.

Impact of Food Emulsions on the Bioaccessibility of Hydrophobic Pesticide Residues in Co-Ingested Natural Products: Influence of Emulsifier and Dietary Fiber Type

In the typical Western diet, fruits and vegetables are often consumed with food products that exist as oil-in-water emulsions, such as creams, dressings, and sauces. Studies have shown that coingestion of fruits and vegetables with emulsions can increase the bioavailability of beneficial lipophilic bioactive agents, such as nutraceuticals or vitamins. Agricultural produce, however, may also be contaminated with low levels of detrimental lipophilic agents, such as hydrophobic pesticides. We therefore examined the impact of coingesting a common agricultural product (tomatoes) with model food emulsions on the bioaccessibility of a hydrophobic pesticide (chlorpyrifos). The impact of emulsifier types (phospholipids, whey protein, Tween 80) and dietary fiber types (xanthan, chitosan, β-glucan) on the bioaccessibility of the pesticide was measured using a simulated gastrointestinal model. Chlorpyrifos bioaccessibility depended on the type of emulsifier used to formulate the emulsions: phospholipids > Tween 80 > whey protein. Dietary fiber type also influenced pesticide bioaccessibility by an amount that depended on the nature of the emulsifier used. Overall, our results suggest that the bioaccessibility of undesirable pesticides on fruits and vegetables will depend on the nature of the emulsions they are consumed with.

Establishing the impact of food matrix effects on the bioaccessibility of nutraceuticals and pesticides using a standardized food model

It is important to establish the impact of food matrix effects on the bioaccessibility of co-ingested substances, such as nutraceuticals, engineered nanomaterials, pharmaceuticals, and pesticides.

Effect of the Composition and Structure of Excipient Emulsion on the Bioaccessibility of Pesticide Residue in Agricultural Products

The influence of co-ingestion of food emulsions with tomatoes on the bioaccessibility of a model pesticide (chlorpyrifos) was studied. Emulsions were fabricated with different oil contents (0-8%), lipid compositions (medium chain triglyceride (MCT) and corn oil), and particle diameters (d₃₂ = 0.17 and 10 μm). The emulsions were then mixed with chlorpyrifos-contaminated tomato puree, and the mixtures were subjected to a simulated gastrointestinal tract (GIT) consisting of mouth, stomach, and small intestine. The particle size, surface charge, and microstructure of the emulsions was measured as they passed through the GIT, and chlorpyrifos bioaccessibility was determined after digestion. The composition and structure of the emulsions had a significant impact on chlorpyrifos bioaccessibility. Bioaccessibility increased with increasing oil content and was higher for corn oil than MCT, but did not strongly depend on oil droplet size. These results suggest that co-ingestion of emulsions with fruits or vegetables could increase pesticide bioaccessibility.

Validation of an efficient method for the determination of pesticide residues in fruits and vegetables using ethyl acetate for extraction

In this study, a version of the "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) method was modified to use ethyl acetate (EtOAc) rather than acetonitrile (MeCN) for extraction in the determination of multiple pesticide residues in fruits and vegetables. EtOAc is better suited than MeCN for gas chromatographic (GC) analysis with electron capture detection (ECD) and nitrogen-phosphorus detection (NPD). The method entailed extraction of 30 g chopped sample plus 5 g NaHCO(3) and 30 g anhydrous Na(2)SO(4) with 60 mL EtOAc using a probe blender. After a centrifugation step, removal of residual water and cleanup were performed using dispersive solid-phase extraction (dispersive-SPE) with MgSO(4) and primary secondary amine (PSA) sorbent. (14)C-labeled chlorpyrifos with liquid scintillation counting was used to assist in optimizing and characterizing the method, and GC-ECD and GC-NPD were used for analysis of 24 selected pesticides. The method was validated using tomato, apple and frozen green bean matrices spiked at 0.05, 0.5, and 5 mg/kg. For 22 of the analytes, recoveries averaged 93% for all three commodities over the validation range with a relative standard deviation of 10% (n = 1182). Lower recoveries of dichlorvos were obtained with the method and iprodione determination was compromised in the green beans by an interfering peak. Typical limits of detection were 0.005-0.01 mg/kg with the method.