Colorimetric detection of the potent carcinogen aflatoxin B1 based on the aggregation of L-lysine-functionalized gold nanoparticles in the presence of copper ions.

L-lysine functionalized gold nanoparticles (AuNPs-Lys) have been widely used for the detection of worldwide interest analytes. In this work, a colorimetric assay for the detection of the carcinogen aflatoxin B1 (AFB1) based on the aggregation of AuNPs-Lys in the presence of copper ions was developed. For this purpose, AuNPs were synthesized in citrate aqueous solution, functionalized, and further characterized by UV-Vis, fluorescence, Fourier transform infrared spectroscopy (FTIR), nanoparticle tracking analysis (NTA), dynamic light scattering (DLS), and transmission electron microscopy (TEM). In general, AuNPS-Lys (~2.73 × 1011 particles) offered a clear colorimetric response in the presence of AFB1 and Cu2+ ions showing linearity in the range of 6.25 to 200 ng AFB1/mL, with a detection limit of 4.18 ng AFB1/mL via photometric inspection. Moreover, the performance of the proposed methodology was tested using the 991.31 AOAC official procedure based on monoclonal antibodies in maize samples artificially contaminated with AFB1. There was a good agreement between the measured AFB1 concentrations in both assays, the average recoveries for the colorimetric and immunoaffinity assays were between 91.2-98.4% and 96.0-99.2%, respectively. These results indicated that the colorimetric assay could be used as a rapid, eco-friendly, and cost-effective platform for the quantification of AFB1 in maize-based products.

Highly efficient adsorptive removal of the carcinogen aflatoxin B1 using the parasitic plant Cuscuta corymbosa Ruiz & Pavon.

The ever-growing consumption of herbs around the globe has motivated the researchers to acquire practical knowledge about other potential applications in human and animal health. In this research, an unmodified adsorbent prepared from the holoparasitic herb C. corymbosa was utilized for the removal of the carcinogen aflatoxin B1 (AFB1) from aqueous solutions. The adsorbent was characterized by Fourier transform near-infrared/mid-infrared spectrophotometry (FT-NIR/MIR), environmental scanning electron microscopy (ESEM), energy-dispersive X-ray fluorescence spectroscopy (EDX), X-ray diffraction (XRD), and point of zero charge (pHpzc). Adsorption experiments were carried out in batch systems, and the experimental data was used for isothermal (Langmuir and Freundlich) and kinetic (linear and non-linear forms of the pseudo-first and pseudo-second order) models. In general, the unmodified adsorbent removed AFB1 independent of the solution pH, showing a theoretical adsorption capacity of 555.76 mg AFB1/g at 303 K, significantly higher than that reported for other plant-based adsorbents and comparable with the efficiency of various inorganic adsorbents. Non-electrostatic attractions such as hydrogen bonding and dispersion forces along with complexation mechanisms were the primary interactions responsible for the adsorption of the pollutant. Our results clearly show that C. corymbosa could be a promising material for practical adsorption applications in the drinking water industry.

Development of a novel cryostructured composite coating of xanthan-bovine collagen-oregano essential oil spraying applied for the preservation of commercial biscuits marketed in Mexico.

Cryostructured gels, better known as cryogels, are a very important emerging class of biomaterials that have diverse applications in food preservation. This work shows a novel alternative to prepare a cryostructured composite coating made from a blend of xanthan, bovine collagen, and oregano essential oil. The composite coating was suitably applied onto the surface of preservative-free biscuits which were stored for 15 days at 25 ± 2°C and 52% ± 1% relative humidity. The evaluation focused mainly on the changes in the physicochemical, textural, and microbiological characteristics of the biscuits. It was found that the coated samples significantly (p < 0.05) decreased moisture absorption, water activity, and fungal growth. However, the composite coating minimally impacted the quality of biscuits in terms of color, texture profile, and surface microstructure. Overall, the cryostructured composite coating constitutes an advance in technological strategies aimed at the preservation of baked products. This will allow, in the future, the development of novel coatings on bakery products to generate new trends in the conservation of their properties and extension of shelf life. This could be achieved through the implementation of new technologies in the food industry, with the aim of making them more environmentally friendly and contributing to the generation of less plastic waste. PRACTICAL APPLICATION: The study and application of cryogels, as innovative systems in the food industry, allow to expand and diversify the materials that can function as coatings to maintain some quality characteristics, in this case in bakery products, so it is important to analyze their effects and consider them to improve conservation processes.

Computational Studies of Aflatoxin B1 (AFB1): A Review.

Aflatoxin B1 (AFB1) exhibits the most potent mutagenic and carcinogenic activity among aflatoxins. For this reason, AFB1 is recognized as a human group 1 carcinogen by the International Agency of Research on Cancer. Consequently, it is essential to determine its properties and behavior in different chemical systems. The chemical properties of AFB1 can be explored using computational chemistry, which has been employed complementarily to experimental investigations. The present review includes in silico studies (semiempirical, Hartree-Fock, DFT, molecular docking, and molecular dynamics) conducted from the first computational study in 1974 to the present (2022). This work was performed, considering the following groups: (a) molecular properties of AFB1 (structural, energy, solvent effects, ground and the excited state, atomic charges, among others); (b) theoretical investigations of AFB1 (degradation, quantification, reactivity, among others); (c) molecular interactions with inorganic compounds (Ag+, Zn2+, and Mg2+); (d) molecular interactions with environmentally compounds (clays); and (e) molecular interactions with biological compounds (DNA, enzymes, cyclodextrins, glucans, among others). Accordingly, in this work, we provide to the stakeholder the knowledge of toxicity of types of AFB1-derivatives, the structure-activity relationships manifested by the bonds between AFB1 and DNA or proteins, and the types of strategies that have been employed to quantify, detect, and eliminate the AFB1 molecule.

The Ability of Chlorophyll to Trap Carcinogen Aflatoxin B1: A Theoretical Approach.

The coordination of one and two aflatoxin B1 (AFB1, a potent carcinogen) molecules with chlorophyll a (chl a) was studied at a theoretical level. Calculations were performed using the M06-2X method in conjunction with the 6-311G(d,p) basis set, in both gas and water phases. The molecular electrostatic potential map shows the chemical activity of various sites of the AFB1 and chl a molecules. The energy difference between molecular orbitals of AFB1 and chl a allowed for the establishment of an intermolecular interaction. A charge transfer from AFB1 to the central cation of chl a was shown. The energies of the optimized structures for chl a show two configurations, unfolded and folded, with a difference of 15.41 kcal/mol. Chl a appeared axially coordinated to the plane (α-down or ß-up) of the porphyrin moiety, either with the oxygen atom of the ketonic group, or with the oxygen atom of the lactone moiety of AFB1. The complexes of maximum stability were chl a 1-α-E-AFB1 and chl a 2-ß-E-AFB1, at -36.4 and -39.2 kcal/mol, respectively. Additionally, with two AFB1 molecules were chl a 1-D-2AFB1 and chl a 2-E-2AFB1, at -60.0 and -64.8 kcal/mol, respectively. Finally, biosorbents containing chlorophyll could improve AFB1 adsorption.

Potential of Kale and Lettuce Residues as Natural Adsorbents of the Carcinogen Aflatoxin B1 in a Dynamic Gastrointestinal Tract-Simulated Model.

Adsorption of the carcinogen aflatoxin B1 (AFB1) onto agro-waste-based materials is a promising alternative over conventional inorganic binders. In the current study, two unmodified adsorbents were eco-friendly prepared from kale and lettuce agro-wastes. A dynamic gastrointestinal tract-simulated model was utilized to evaluate the removal efficiency of the sorptive materials (0.5%, w/w) when added to an AFB1-contaminated diet (100 µg AFB1/kg). Different characterization methodologies were employed to understand the interaction mechanisms between the AFB1 molecule and the biosorbents. Based on adsorption results, the biosorbent prepared from kale was the best; its maximum adsorption capacity was 93.6%, which was significantly higher than that of the lettuce biosorbent (83.7%). Characterization results indicate that different mechanisms may act simultaneously during adsorption. Non-electrostatic (hydrophobic interactions, dipole-dipole interactions, and hydrogen bonding) and electrostatic interactions (ionic attractions) together with the formation of AFB1-chlorophyll complexes appear to be the major influencing factors driving AFB1 biosorption.

Ability of low contents of biosorbents to bind the food carcinogen aflatoxin B1in vitro.

In vitro experiments were conducted to evaluate the effectiveness of two new biosorbents (lettuce and field horsetail) in removing aflatoxin B1 (AFB1). Formosa firethorn was used as reference material. The adsorption of AFB1 (190 ng/mL) was investigated at two sorbent contents (0.5% and 0.1% w/v) and three pHs (2, 5, and 7). Batch experiments were performed at 40 °C for 2 h. Several methodologies were used to characterize the nature of the biosorbent-AFB1 interaction. In general, when using biosorbents at 0.5% w/v, AFB1 was well adsorbed by the three tested biomaterials (70 to 100%). Furthermore, with the lowest biosorbent content (0.1% w/v), significant AFB1 adsorption efficiencies were attained at pH 5 (33 to 50%). Nevertheless, at pH 7, lettuce showed the highest ability against AFB1 removal (95%). Further characterization of the AFB1-loaded biosorbents demonstrated that chemical and physical mechanisms were involved in the adsorption process.

Detoxification of Aflatoxin-Contaminated Maize by Neutral Electrolyzed Oxidizing Water.

Aflatoxins, a group of extremely toxic mycotoxins produced by Aspergillus flavus, A. parasiticus and A. nomius, can occur as natural contaminants of certain agricultural commodities, particularly maize. These toxins have been shown to be hepatotoxic, carcinogenic, mutagenic and cause severe human and animal diseases. The effectiveness of neutral electrolyzed oxidizing water (NEW) on aflatoxin detoxification was investigated in HepG2 cells using several validation methodologies such as the 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide assay, the induction of lipid peroxidation, the oxidative damage by means of glutathione modulation, the Ames test and the alkaline Comet assay. Our results showed that, after the aflatoxin-contaminated maize containing 360 ng/g was soaked in NEW (60 mg/L available chlorine, pH 7.01) during 15 min at room temperature, the aflatoxin content did not decrease as confirmed by the immunoaffinity column and ultra performance liquid chromatography methods. Aflatoxin fluorescence strength of detoxified samples was similar to untreated samples. However, aflatoxin-associated cytotoxicity and OPEN ACCESS Toxins 2015, 7 4295 genotoxicity effects were markedly reduced upon treatment. According to these results, NEW can be effectively used to detoxify aflatoxin-contaminated maize.

Cytotoxic and genotoxic evaluation of tortillas produced by microwave heating during alkaline-cooking of aflatoxin-contaminated maize.

UNLABELLED: In vitro cytotoxicity and genotoxicity induction by aflatoxin B1 (AFB1) from maize (ME) and tortillas (TE) produced by microwave nixtamalization were investigated in monkey kidney (Vero cells) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, the induction of lipid peroxidation, the oxidative damage by means of glutathione (GSH) depletion, and the Salmonella-microsomal screening system (Ames test). Our results showed that, at higher concentrations, both ME and TE extracts that contained varying amounts of aflatoxin caused a considerable decrease in Vero cell viability (up to 37%) after 4 h of exposure. Aflatoxins from ME induced greater oxidative damage by enhancing lipid peroxidation (up to 6.05 ± 0.14 µmol/mg protein) as compared to TE; however, TE also induced significant malondialdehyde formation in particular at the higher aflatoxin concentration tested (up to 2.7 ± 0.19 µmol/mg protein). The decrease in GSH level was also more pronounced in ME as compared to TE. Moreover, the Ames test results indicated that the mutagenic activity of TE was greatly reduced compared with that of ME based on his(-) → his(+) reversions in the Salmonella TA100 strain. According to these results, it is concluded that the microwave nixtamalization procedure reduced aflatoxins and their in vitro toxicity and mutagenic activity. PRACTICAL APPLICATION: In Mexico, aflatoxins are often found in maize destined for the tortilla industry; consequently, tortilla consumption invariably leads to an important intake of intact and/or modified aflatoxin molecules caused by the thermal-alkaline treatment used during production. Therefore, it is of the highest importance to check whether such intake has the potential to lead to higher risk for adverse human health effects. In view of these considerations, in vitro tests may thus be useful for predicting the potential cytotoxicity and genotoxicity of tortillas produced for human consumption using aflatoxin-contaminated maize.

Efficacy of Microwave-Heating during Alkaline Processing of Fumonisin-Contaminated Maize.

BACKGROUND: Fumonisins (a family of foodborne carcinogenic mycotoxins) cause health hazards to humans and animals in developing countries, and has also economic implications. Therefore, the efficacy of a novel environmental friendly nixtamalization procedure to make tortillas (the main staple food for the Mexican population) was investigated. METHODS: Maize contaminated with 2136.67 ng/g total fumonisins was processed into tortillas, starting with maize grits mixed with water and calcium hydroxide that was cooked in a microwave field at 2.45 GHz during 3.75 min, and steeped 3.5 h at room temperature. The steeped maize grits (nixtamal) was stone-ground into masa (maize dough), which was then used to make tortillas. Total fumonisin content was determined using monoclonal antibody columns. RESULTS: Masa contained 1998.33 ng/g total fumonisins, which represents 6.5% toxin reduction. Nevertheless, fumonisin concentration was reduced significantly in tortillas (up to 985.33 ng/g) due to the cooking process, corresponding to a cumulative toxin degradation of 54%. Tortillas were below the maximum tolerated level, considering the European Union regulatory limit for fumonisins in maize (1000 ng/g). The physicochemical and technological properties of tortillas were also considered within the acceptable margins of quality. CONCLUSION: Microwave nixtamalization was not a feasible method to reduce fumonisin content in masa to acceptable levels; however, an effective extra-reduction occurred when masa was baking into tortillas.

Role of lactone ring in structural, electronic, and reactivity properties of aflatoxin B1: a theoretical study.

This study involved quantum mechanical calculations to explain the chemical behavior of the lactone ring of aflatoxin B1, which is a carcinogenic hazardous compound. The aflatoxin B1 compound, produced by the fungi Aspergillum flavus, was studied with the B3LYP/6-311+G(d,p) method; its reactivity properties were accounted for by means of the calculated geometrical and electronic parameters. The results obtained indicate that the fused A, B, C, and D rings of aflatoxin adopt a continuous planar conformation. The carbon atom of the lactone group presents a highly electrophilic character, since the population analysis yields a high positive charge for this atom, whereas high negative charges were recorded for both oxygen sites of that group. Thus, in an acidic aqueous medium, the oxygen atoms could be protonated and the carbon site may suffer a nucleophilic attack by water. Accordingly, the OC-O bond length has been lengthened substantially. So it was demonstrated that the lactonic ring of aflatoxin B1 is hydrolyzed under acidic conditions by an acid-acyl bimolecular mechanisms, A(AC)2, suggesting the deletion of its carcinogenic properties.

Efecto de la adición de ácido cítrico sobre la degradación de las aflatoxinas y las propiedades funcionales de productos extrudidos de sorgo / Effect of citric acid addition on aflatoxin degradation and on functional properties of extruded sorghum products / Efeito da adição de ácido cítrico sobre a degradação das aflatoxinas e as propriedades funcionais de produtos extrudidos de sorgo

Harina de sorgo contaminada con aflatoxinas (AFB1+AFB2) a una concentración total de 140µg·kg-1, fue sometida a extrusión termoplástica usando un perfil de temperatura de 60-80-100ºC. El contenido de humedad (CH) de la harina fue ajustado a 20, 25 y 30% mediante la adición de diferentes cantidades de ácido cítrico (AC) acuoso a concentraciones de 0; 0,5; 1; 2; 4 y 8N. El perfil de temperatura, en combinación con el CH y la concentración de AC, afectaron significativamente la cantidad de aflatoxinas recuperadas en los extrudidos; el máximo porcentaje de eliminación fue de 35,5%. En los extrudidos procesados con altos CH y concentraciones de AC se encontraron los valores más altos en la diferencia de color (DE), así como los valores más bajos en viscosidad. Los índices de expansión fueron favorecidos a mayores CH y altas concentraciones de AC. Los mayores valores de fuerza al corte se encontraron en los extrudidos elaborados con un mayor CH; sin embargo, no se presentaron diferencias significativas para las diferentes concentraciones de AC evaluadas. Empleando condiciones moderadas durante la extrusión en combinación con altas concentraciones de AC se obtuvieron extrudidos con aceptable pH, color, viscosidad, así como con buenas propiedades funcionales y texturales.

Sorghum flour contaminated by aflatoxin at a concentration of 140µg·kg-1 was extrusion-cooked in a single screw extruder with a temperature profile of 60-80-100°C. The moisture content (MC) of the flour was adjusted to 20, 25 and 30% by adding aqueous citric acid (CA) at concentrations of 0, 0.5, 1, 2, 4 and 8N. The temperature profile in combination with the MC and CA concentrations significantly affected the extent of aflatoxin reduction in the extruded sorghum; the maximum percentage of aflatoxin reduction was 35.5%. In extruded sorghum prepared with high MC and CA concentrations, the highest values in color difference (DE) and smallest values of viscosity were found. The expansion index was favored by higher MC and CA concentrations. The highest cutting force values were found in extruded products prepared with a higher MC, but there were no significant differences between those values and the different CA concentrations evaluated. Using moderate extrusion conditions in combination with higher concentrations of CA, products were obtained with acceptable pH, color, viscosity, as well as with good textural and functional properties.

Farinha de sorgo contaminada com aflatoxinas (AFB1+AFB2) na concentração total de 140µg·kg-1, foi submetida ao proceso de extrusão termoplástica usando um perfil de temperatura de 60-80-100ºC. O conteúdo de umidade (CH) da farinha foi ajustado a 20, 25 e 30% mediante a adição de diferentes quantidades de ácido cítrico (AC) aquoso em concentrações de 0; 0,5; 1; 2; 4 e 8N. O perfil de temperatura, combinado com o CH e a concentração de AC, afetaram significativamente a quantidade de aflatoxinas recuperadas nos extrudidos; a máxima porcentagem de eliminação foi de 35,5%. Nos extrudidos procesados com alto CH e concentração de AC se encontraram os valores mais altos na diferença de cor (DE), assim como os valores mais baixos em viscosidade. Os índices de expansão foram favorecidos a maior CH e altas concentrações de AC. Os maiores valores de força ao corte se encontraram nos extrudidos elaborados com maior CH; no entanto, não se apresentaram diferenças significativas para as diferentes concentrações de AC avaliadas. Utilizando condiciones moderadas durante a extrusão em combinação com altas concentrações de AC se obtiveram extrudidos com aceitável pH, cor, viscosidade, assim como com boas propriedades funcionais e texturais.

Evaluación de una metodología para determinar características de textura de tortilla de maíz (Zea mays L) / Evaluation of a methodology to determine texture characteristics maize (Zea mays L) tortilla

La tortilla de maíz (Zea mays L.), es el principal alimento de la población Mexicana, con un consumo anual de 12 millones de toneladas. A pesar de su alto consumo, existe una gran variabilidad en las características de calidad de la tortilla producida comercialmente, principalmente las de textura. Para evaluar la textura de las tortillas se han reportado algunos métodos, pero los parámetros y valores obtenidos han sido muy variados y no comparten una base adecuada para su comparación. Además, la confiabilidad de los parámetros reportados, utilizando un texturómetro, tampoco ha sido evaluada. En este estudio se seleccionaron dos formas de la muestra, rectangular y probeta, así como la de varios parámetros de calidad obtenidos con el texturómetro (fuerza máxima, área total, área hasta fuerza máxima, elasticidad y elongación) y se evaluó su confiabilidad con base a su repetibilidad. De acuerdo a los resultados, la forma de "probeta" fue la más adecuada para las pruebas de tensión y elasticidad. Para la fuerza al corte, las dos formas resultaron con buena repetibilidad. La fuerza máxima fue el parámetro de mayor confiabilidad para las pruebas de tensión y corte, con una repetibilidad de 0.95 y 0.99 respectivamente. La elasticidad resultó con buena repetibilidad cuando la prueba se realizó con la forma de probeta (0.94). Utilizando el texturómetro y la forma de muestra tipo probeta, los parámetros determinados muestran alto grado de confiabilidad y facilitan la comparación de datos de textura para tortillas de maíz