Occurrence of zearalenone in corn meal commercialized in south region of Brazil and daily intake estimates in the Brazilian population

pH-induced interaction mechanism of zearalenone with zein: Binding characteristics, conformational structure and intermolecular forces

Zein-bound zearalenone (ZEN) complexes are naturally existed in maize by their spontaneous interaction, which significantly impacts the risk assessment of ZEN. Additionally, the pH levels in processing could affect the binding or release of zein-bound ZEN. In this study, pH-induced interaction mechanism of ZEN with zein were studied. Results showed that the acid conditions increased the binding constant (Ka) from 3.46 to 10.0 × 104 L/mol, binding energy from -17.38 to -43.49 kJ mol-1. By increasing hydrophobic interaction and hydrogen bond of ZEN with zein, the binding of ZEN with zein was promoted, forming zein-bound ZEN. Whereas, alkaline conditions decreased the Ka to 1.45 × 104 L/mol and binding energy to 148.48 kJ mol-1, weakened ZEN-zein interaction and stretched zein molecules, resulting the release of ZEN from zein. This study could provide important theoretical basis for perfecting risk assessment and controlling zein-bound ZEN during processing.

An enhanced fluorescent sensor system based on molecularly imprinted polymer chips with silver nanoparticles for highly-sensitive zearalenone analysis

A novel enhanced fluorescent sensor system for zearalenone (ZON) determination in flour samples is presented. The ZON-selective molecularly imprinted polymer (MIP) films were developed with a computational modelling method and synthesised with cyclododecyl-2,4-dihydroxybenzoate as a "dummy" template and ethylene glycol methacrylate phosphate as a functional monomer acted as the selective recognition elements for ZON fluorescence detection. Spherical silver nanoparticles (AgNPs) were embedded in the MIP films' structure to enhance the sensor sensitivity. The imprinted films showed a high ZON recognition ability compared to non-imprinted films. Various factors that affected the measurement of the analysed sample were investigated and optimised. Embedding the AgNPs in the MIP films' structure led to an enhanced sensitivity (up to a 200-fold decrease of LOD) compared to unmodified MIP films. This fluorescent sensor system provided ZON analysis with high sensitivity, specificity, and a wider linear dynamic range of 5 ng mL^-1 to 25 μg mL^-1. An enhanced fluorescent sensor system based on MIP chips with embedded AgNPs could detect trace amounts of ZON in foods and feedstuffs with high sensitivity and selectivity.

Deoxynivalenol and Zearalenone-Synergistic or Antagonistic Agri-Food Chain Co-Contaminants?

Deoxynivalenol (DON) and Zearalenone (ZEN) are two commonly co-occurring mycotoxins produced by members of the genus Fusarium. As important food chain contaminants, these can adversely affect both human and animal health. Critically, as they are formed prior to harvesting, their occurrence cannot be eliminated during food production, leading to ongoing contamination challenges. DON is one of the most commonly occurring mycotoxins and is found as a contaminant of cereal grains that are consumed by humans and animals. Consumption of DON-contaminated feed can result in vomiting, diarrhoea, refusal of feed, and reduced weight gain in animals. ZEN is an oestrogenic mycotoxin that has been shown to have a negative effect on the reproductive function of animals. Individually, their mode of action and impacts have been well-studied; however, their co-occurrence is less well understood. This common co-occurrence of DON and ZEN makes it a critical issue for the Agri-Food industry, with a fundamental understanding required to develop mitigation strategies. To address this issue, in this targeted review, we appraise what is known of the mechanisms of action of DON and ZEN with particular attention to studies that have assessed their toxic effects when present together. We demonstrate that parameters that impact toxicity include species and cell type, relative concentration, exposure time and administration methods, and we highlight additional research required to further elucidate mechanisms of action and mitigation strategies.

Effect of temperature and pH on the conversion between free and hidden zearalenone in zein

Food processing might induce the transformation of hidden ZEN (zein-bound ZEN) in maize. The objective of this study was to assess the effect of processing factors on free ZEN and hidden ZEN. After zein was treated under different temperature and pH, ZEN was quantified in samples before and after in vitro digestion. The ratios of hidden to total ZEN in zein are decreased from 54.25% to 40.74% after thermal treatment and from 54.25% to 0 after alkaline treatment, respectively. Conversely, acid treatment increased the ratio of hidden to total ZEN from 54.25% to 100%. Thus, it can be concluded that thermal or alkaline condition induced the conversion of hidden ZEN to free ZEN while acid condition promoted the ZEN-zein interactions to form the hidden ZEN. Overall, temperature and pH values played a vital role in the conversion of hidden ZEN during food processing.

Mycotoxins in cereals and cereal-based products: Incidence and probabilistic dietary risk assessment for the Brazilian population

A probabilistic dietary risk assessment on mycotoxins was conducted using the Monte Carlo Risk Assessment software, with consumption data from the 2008/2009 Brazilian Household Budget Survey for individuals who were at least 10 years old and occurrence data for 646 samples of rice, maize, wheat, and their products, collected in the Federal District and in the state of Rio Grande do Sul, Brazil. Processing factors were estimated and applied to concentration data. Chronic exposure was estimated for fumonisins (free and bound/hidden), deoxynivalenol (DON) (including the acetylated forms) and zearalenone (ZON) (including alfa-zearalenol) and acute exposure was estimated for DON. For the general population, the chronic exposure exceeded the safe exposure levels at the 95P for DON and at the 99P for fumonisins. Additionally, safe level exceedance occurred at the 97.5P for fumonisins and at the 95P for DON for teenagers, as well as at the 99P for fumonisins for women of child-bearing-age. No exceedances were found for chronic exposure to ZON and acute exposure to DON. Maize couscous contributed most of the total fumonisins (91%) and ZON intakes (~40%) and bread to total intake of DON (~30%). Further studies should be conducted with updated Brazilian consumption data, which should include information for individuals aged less than 10 years old.

A simple mesoporous silica nanoparticle-based fluorescence aptasensor for the detection of zearalenone in grain and cereal products

Zearalenone (ZEN) is a type of estrogenic mycotoxin commonly occurring in cereals. The aim of this study was to design a simple, rapid, inexpensive and ultrasensitive fluorescence assay for the determination of ZEN. Here, amino-modified mesoporous silica nanoparticles (MSNs-NH₂) were synthesized to be the positive charge-rich reactor. A 6-carboxy-fluorescein-labeled aptamer (aptamer-FAM) was designed as the signal probe, ZEN-capture probe and negative charge reactor. In the absence of ZEN, the negatively charged aptamer-FAM combined with the positively charged MSNs-NH₂ in an electrostatic manner. In the presence of ZEN, the fluorescence intensity in the supernatant increased significantly because the aptamer-FAM could bind to ZEN instead of MSNs-NH₂. Under the optimal experimental conditions, this assay exhibited excellent specificity, repeatability and a wide linearity range of 0.005-150 ng/mL, with a detection limit of 0.012 ng/mL. Additionally, it showed high recovery (83.3-101.5%) for the spiked samples. There was no statistically significant difference in the ZEN concentrations detected by the proposed assay and HPLC in naturally contaminated samples. Overall, this design provides a new strategy for the rapid, inexpensive and sensitive detection of ZEN, and it could be applied to develop fluorometric assays for different targets by the selection of appropriate aptamers. Graphical abstract.