Determination of mycotoxins in foods: current state of analytical methods and limitations

A review of biomolecules conjugated lanthanide up-conversion nanoparticles-based fluorescence probes in food safety and quality monitoring applications

Upconversion nanoparticles (UCNPs) are known to possess unique characteristics, which allow them to overcome a number of issues that plague traditional fluorescence probes. UCNPs have been employed in a variety of applications, but it is arguably in the realm of optical sensors where they have shown the most promise. Biomolecule conjugated UCNPs-based fluorescence probes have been developed to detect and quantify a wide range of analytes, from metal ions to biomolecules, with great specificity and sensitivity. In this review, we have given much emphasis on the recent trends and progress in the preparation strategies of bioconjugated UCNPs and their potential application as fluorescence sensors in the trace level detection of food industry-based toxicants and adulterants. The paper discusses the preparation and functionalisation strategies of commonly used biomolecules over the surface of UCNPs. The use of different sensing strategies namely heterogenous and homogenous assays, underlying fluorescence mechanisms in the detection process of food adulterants are summarized in detail. This review might set a precedent for future multidisciplinary research including the development of novel biomolecules conjugated UCNPs for potential applications in food science and technology.

Interconnectable 3D-printed sample processing modules for portable mycotoxin screening of intact wheat

BACKGROUND

The increasing demand for food and feed products is stretching the capacity of the food value chain to its limits. A key step for ensuring food safety is checking for mycotoxin contamination of wheat. However, this analysis is typically performed by rather complex and expensive chromatographic methods, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS). These costly methods require extensive sample preparation that is not easily carried out at different points along the food supply chain. To overcome such challenges in sample processing, an inexpensive and portable sample preparation device was needed, that required low skill, for rapid sample-to-result mycotoxin screening.

RESULTS

We describe 3D-printed and interconnectable modules for simple, integrated and on-site sample preparation, including grinding of wheat kernels, and solvent-based extraction. We characterized these 3D-printed modules for mycotoxin screening and benchmarked them against a laboratory mill using commercial lateral flow device(s) (LFD) and in-house validated LC-MS/MS analysis. Different integrated sieve configurations were compared based on grinding efficiency, and we selected a sieve size of 2 mm allowing grinding of 10 g of wheat within 5 min. Moreover, 10 first time-users were able to operate the grinder module with minimal instructions. Screening for deoxynivalenol (DON) in naturally contaminated samples at the regulatory/legal limit (1.25 mg kg-1) was demonstrated using the developed 3D-printed prototype. The whole process only takes 15 min, from sample preparation to screening result. The results showed a clear correlation (R2 = 0.96) between the LFD and LC-MS/MS.

SIGNIFICANCE

Our findings demonstrate the potential of 3D-printed sample handling equipment as a valuable extension of existing analytical procedures, facilitating the on-site implementation of rapid methods for the determination of mycotoxins in grains. The presented prototype is inexpensive with material costs of 2.5€, relies on biodegradable 3D printing filament and can be produced with consumer-grade printers, making the prototype readily available. As a future perspective, the modular character of our developed tool kit will allow for adaptation to other hard food commodities beyond the determination of DON in wheat.

Study of co-occurrence of mycotoxins in cocoa beans in Brazil by liquid chromatography-tandem mass spectrometry (LC-MS/MS)

In this study, 135 samples of cocoa beans collected in the Amazon and Atlantic Forest regions of Brazil were analysed to evaluate the possible co-occurrence of 34 mycotoxins. The results indicate that 42% of the cocoa samples exhibited quantifiable levels for 11 mycotoxins: aflatoxins (AFs) B1, B2 and G1; ochratoxin A; citrinin; cyclopiazonic acid; tenuazonic acid; paxilline; sterigmatocystin; zearalenone and fumonisin B2. Of the samples, 18% exhibited the co-occurrence of up to six mycotoxins. No toxins belonging to the groups of trichothecenes or ergot alkaloids were detected. Contingency analysis of the incidence of mycotoxins did not show significant differences between the two regions evaluated. Seven samples were contaminated with AFs, while only one contained ochratoxin A above 10 μg kg-1. The accuracy of the method was evaluated by proficiency testing for ochratoxin A, where satisfactory Z-scores were obtained.

Foodborne Diseases Due to Underestimated Hazard of Joint Mycotoxin Exposure at Low Levels and Possible Risk Assessment

The subject of this review paper is to evaluate the underestimated hazard of multiple mycotoxin exposure of animals/humans for the appearance of foodborne ailments and diseases. The significance of joint mycotoxin interaction in the development of foodborne diseases is discussed, and appropriate conclusions are made. The importance of low feed/food levels of some target mycotoxins co-contaminations in food and feedstuffs for induction of target foodborne mycotoxicoses is also studied in the available literature. The appropriate hygiene control and the necessary risk assessment in regard to possible hazards for animals and humans are also discussed, and appropriate suggestions are made. Some internationally recognized prophylactic measures, management of the risk, and the necessity of elaboration of new international regulations in regard to the maximum permitted levels are also carefully discussed and analysed in the cases of multiple mycotoxin contaminations. The necessity of harmonization of mycotoxin regulations and control measures at international levels is also discussed in order to facilitate food trade between the countries and to ensure global food safety.

Occurrence and Exposure Assessment of Major Mycotoxins in Foodstuffs from Algeria

Cereal-based products, nuts and dried fruits are staple foods for the Algerian population. However, these foodstuffs may be sources of harmful mycotoxins, with negative impacts on human health. The purpose of this study was to investigate the occurrences and levels of aflatoxins (B1, B2, G1 and G2), ochratoxin A (OTA), deoxynivalenol (DON) and zearalenone (ZEA) in 198 samples of nuts, dried fruits and cereal products commercialized in Algeria, as well as to calculate the estimated daily intakes (EDIs). Aflatoxins were found in 26.2% of the nut samples (in peanuts and almonds, but not in walnuts), 38.7% of the dried fruit samples (in dried figs, dates and bradj pastries) and 47.9% of the cereal-based products (in rechta noodles and metlou bread, but not in couscous), with mean concentrations ranging from 0.03 to 0.49 μg/kg. OTA occurred in 16.9% of the cereal-based samples, averaging 0.15 μg/kg, but it was not detected in nuts or dried fruits. The incidence of DON in the cereal-based products was 85.9% on average, with a mean concentration from 90 to 123 μg/kg. ZEA mycotoxin was not detected in any samples. Four peanut samples exceeded the EU maximum level for aflatoxin B1 set at 2 μg/kg, while three of them surpassed the maximum level for the sum of aflatoxins (4 μg/kg). Traditional foods such as bradj, rechta and metlou were significant sources of aflatoxins, with MOE (margin of exposure) values ranging from 648 to 9333, indicating a potential risk for the Algerian population.

An aptamer-functionalized photonic crystal sensor for ultrasensitive and label-free detection of aflatoxin B1

As a novel optical responsive material, photonic crystal is a promising sensing material in the recognition and detection of small molecules. Herein, a label-free composite sensor for aflatoxin B1 (AFB1) based on aptamer-functionalized photonic crystal arrays was successfully developed. Three-dimensional photonic crystals (3D PhCs) with a controllable number of layers were produced by a layer-by-layer (LBL) approach, and the introduction of gold nanoparticles (AuNPs) facilitated the immobilization procedure of recognition element aptamers, thus creating the AFB1 sensing detection system (AFB1-Apt 3D PhCs). The sensing system AFB1-Apt 3D PhCs exhibited a good linearity in the wide range of 1 pg mL^-1-100 ng mL^-1 AFB1 with a limit of detection (LOD) of 0.28 pg mL^-1. Furthermore AFB1-Apt 3D PhC was successfully applied in the determination of AFB1 in the millet and beer samples with good recovery. The sensing system performed ultrasensitive and label-free detection to the target, which could be further applied in the fields of food safety, clinical diagnosis or environmental monitoring, establishing an efficient and rapid universal detection platform.

Mycotoxins in Raw Bovine Milk: UHPLC-QTrap-MS/MS Method as a Biosafety Control Tool

Mycotoxins are compounds produced by several fungi that contaminate agricultural fields and, either directly or by carry-over, final food products. Animal exposure to these compounds through contaminated feed can lead to their excretion into milk, posing threats to public health. Currently, aflatoxin M1 is the sole mycotoxin with a maximum level set in milk by the European Union, as well as the most studied. Nonetheless, animal feed is known to be contaminated by several groups of mycotoxins with relevance from the food safety point of view that can be carried over into milk. To evaluate the multi-mycotoxin occurrence in this highly consumed food product it is crucial to develop precise and robust analytical methodologies towards their determination. In this sense, an analytical method for the simultaneous identification of 23 regulated, non-regulated, and emerging mycotoxins in raw bovine milk using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) was validated. A modified QuEChERS protocol for extraction purposes was used, and further validation was performed by assessing the selectivity and specificity, limits of detection and quantification (LOD and LOQ), linearity, repeatability, reproducibility, and recovery. The performance criteria were compliant with mycotoxin-specific and general European regulations for regulated, non-regulated, and emerging mycotoxins. The LOD and LOQ ranged between 0.001 and 9.88 ng mL−1 and 0.005 and 13.54 ng mL−1, respectively. Recovery values were between 67.5 and 119.8%. The repeatability and reproducibility parameters were below 15 and 25%, respectively. The validated methodology was successfully applied to determine regulated, non-regulated, and emerging mycotoxins in raw bulk milk from Portuguese dairy farms, proving the importance of widening the monitoring scope of mycotoxins in dairy products. Additionality, this method presents itself as a new strategic and integrated biosafety control tool for dairy farms for the analysis of these natural and relevant human risks.

Environmental Conditions After Fusarium Head Blight Visual Symptom Development Affect Contamination of Wheat Grain with Deoxynivalenol and Deoxynivalenol-3-Glucoside

Fusarium head blight (FHB) of wheat, caused by the fungus Fusarium graminearum, is associated with grain contamination with mycotoxins such as deoxynivalenol (DON). Although FHB is often positively correlated with DON, this relationship can break down under certain conditions. One possible explanation for this could be the conversion of DON to DON-3-glucoside (D3G), which is typically missed by common DON testing methods. The objective of this study was to quantify the effects of temperature, relative humidity (RH), and preharvest rainfall on DON, D3G, and the D3D/DON relationship. D3G levels were higher in grain from spikes exposed to 100% RH than to 70, 80, or 90% RH at 20 and 25°C across all tested levels of mean FHB index (percentage of diseased spikelets per spike). Mean D3G contamination was higher at 20°C than at 25 or 30°C. There were significantly positive linear relationships between DON and D3G. Rainfall treatments resulted in significantly higher mean D3G than the rain-free check and induced preharvest sprouting, as indicated by low falling numbers (FNs). There were significant positive relationships between the rate of increase in D3G per unit increase in DON (a measure of conversion) and sprouting. As FN decreased, the rate of D3G conversion increased, and this rate of conversion per unit decrease in FN was greater at relatively low than at high mean DON levels. These results provide strong evidence that moisture after FHB visual symptom development was associated with DON-to-D3G conversion and constitute valuable new information for understanding this complex disease-mycotoxin system.

MXene-based aptasensor for the detection of aflatoxin in food and agricultural products

The detection of toxins that contaminate food needs highly sensitive and selective techniques to prevent substantial monitory loss. In this regard, various nanostructured material-enabled biosensors, have recently been developed to improve the detection of food toxins among them aflatoxin is the prevalent one. The biosensor-based detection of aflatoxin is quick, cheaper, and needs less skilled personnel, therefore overcoming the shortcomings of conventional techniques such as LC/MS-MS, HPLC, and ELISA assays. 2D MXenes manifest as an efficient material for biosensing due to their desirable biocompatibility, magnificent mechanical strength, easiness of surface functionalization, and tuneable optical and electronic features. Contrary to this, aptamers as biorecognition elements (BREs) possess high selectivity, sensitivity, and ease of synthesis when compared to conventional BREs. In this review, we explored the most cutting-edge aptamer-based MXene-enabled biosensing technologies for the detection of the most poisonous mycotoxins (i.e., Aflatoxins) in food and environmental matrices. The discussion begins with the synthesis processes and surface functionalization/modification of MXenes. Computational approaches for designing aptasensors and advanced data analysis based on artificial intelligence and machine learning with special emphasis over Internet-of-Thing integrated biosensing devices has been presented. Besides, the advantages of aptasensors over conventional methods along with their limitations have been briefed. Their benefits, drawbacks, and future potential are discussed concerning their analytical performance, utility, and on-site adaptability. Additionally, next-generation MXene-enabled biosensing technologies that provide end users with simple handling and improved sensitivity and selectivity have been emphasized. Owing to massive applicability, economic/commercial potential of MXene in current and future perspective have been highlighted. Finally, the existing difficulties are scrutinized and a roadmap for developing sophisticated biosensing technologies to detect toxins in various samples in the future is projected.

Current Advances, Research Needs and Gaps in Mycotoxins Biomonitoring under the HBM4EU-Lessons Learned and Future Trends

Mycotoxins are natural metabolites produced by fungi that contaminate food and feed worldwide. They can pose a threat to human and animal health, mainly causing chronic effects, e.g., immunotoxic and carcinogenic. Due to climate change, an increase in European population exposure to mycotoxins is expected to occur, raising public health concerns. This urges us to assess the current human exposure to mycotoxins in Europe to allow monitoring exposure and prevent future health impacts. The mycotoxins deoxynivalenol (DON) and fumonisin B1 (FB1) were considered as priority substances to be studied within the European Human Biomonitoring Initiative (HBM4EU) to generate knowledge on internal exposure and their potential health impacts. Several policy questions were addressed concerning hazard characterization, exposure and risk assessment. The present article presents the current advances attained under the HBM4EU, research needs and gaps. Overall, the knowledge on the European population risk from exposure to DON was improved by using new harmonised data and a newly derived reference value. In addition, mechanistic information on FB1 was, for the first time, organized into an adverse outcome pathway for a congenital anomaly. It is expected that this knowledge will support policy making and contribute to driving new Human Biomonitoring (HBM) studies on mycotoxin exposure in Europe.

A Simple Structure-Switch Aptasensor Using Label-Free Aptamer for Fluorescence Detection of Aflatoxin B1

Aflatoxin B1 (AFB1) is one of the mycotoxins produced by Aspergillus flavus and Aspergillus parasiticus, and it causes contamination in foods and great risk to human health. Simple sensitive detection of AFB1 is important and demanded for food safety and quality control. Aptamers can specifically bind to targets with high affinity, showing advantages in affinity assays and biosensors. We reported an aptamer structure-switch for fluorescent detection of aflatoxin B1 (AFB1), using a label-free aptamer, a fluorescein (FAM)-labeled complementary strand (FDNA), and a quencher (BHQ1)-labeled complementary strand (QDNA). When AFB1 is absent, these three strands assemble into a duplex DNA structure through DNA hybridization, making FAM close to BHQ1, and fluorescence quenching occurs. In the presence of AFB1, the aptamer binds with AFB1, instead of hybridizing with QDNA. Thus, FAM is apart from BHQ1, and fluorescence increases with the addition of AFB1. This assay allowed detection of AFB1 with a detection limit of 61 pM AFB1 and a dynamic concentration range of 61 pM to 4 μM. This aptamer-based method enabled detection of AFB1 in complex sample matrix (e.g., beer and corn flour samples).

Single-step noncompetitive immunocomplex immunoassay for rapid aflatoxin detection

Owing to the high carcinogenicity of aflatoxins, these toxic secondary metabolites pose a severe risk to human and animal health and can have major economic implications. Herein, we report the development of a noncompetitive immunoassay for aflatoxins based on a monoclonal capture antibody and a unique anti-immunocomplex (anti-IC) antibody fragment (scFv) isolated from a synthetic antibody repertoire. The anti-IC scFv recognizes the immunocomplex and enables the development of noncompetitive sandwich-type assays despite the small size of the analyte. The single-step assay developed in this work, with a detection limit of 70 pg mL^-1, could detect aflatoxins within 15 min. The assay was applied to the analysis of spiked food samples, and the results showed that the method could provide a rapid and simple tool for aflatoxin detection. Moreover, the work demonstrates the potential of anti-IC antibodies and non-competitive immunoassays for the analysis of small molecule contaminants.

Citrinin Mycotoxin Contamination in Food and Feed: Impact on Agriculture, Human Health, and Detection and Management Strategies

Citrinin (CIT) is a mycotoxin produced by different species of Aspergillus, Penicillium, and Monascus. CIT can contaminate a wide range of foods and feeds at any time during the pre-harvest, harvest, and post-harvest stages. CIT can be usually found in beans, fruits, fruit and vegetable juices, herbs and spices, and dairy products, as well as red mold rice. CIT exerts nephrotoxic and genotoxic effects in both humans and animals, thereby raising concerns regarding the consumption of CIT-contaminated food and feed. Hence, to minimize the risk of CIT contamination in food and feed, understanding the incidence of CIT occurrence, its sources, and biosynthetic pathways could assist in the effective implementation of detection and mitigation measures. Therefore, this review aims to shed light on sources of CIT, its prevalence in food and feed, biosynthetic pathways, and genes involved, with a major focus on detection and management strategies to ensure the safety and security of food and feed.

Molecular super-gluing: a straightforward tool for antibody labelling and its application to mycotoxin biosensing

Mycotoxins are low molecular weight toxic compounds, which can cause severe health problems in animals and humans. Immunoassays allow rapid, simple and cost-effective screening of mycotoxins. Sandwich assays with a direct readout provide great improvement in terms of selectivity and sensitivity, compared to the widely used competitive assay formats, for the analysis of low molecular weight molecules. In this work, we report a non-competitive fluorescence anti-immune complex (IC) immunoassay, based on the specific recognition of HT-2 toxin with a pair of recombinant antibody fragments, namely antigen-binding fragment (Fab) (anti-HT-2 (10) Fab) and single-chain variable fragment (scFv) (anti-IC HT-2 (10) scFv). The SpyTag and SpyCatcher glue proteins were applied for the first time as a bioconjugation tool for the analysis of mycotoxins. To this aim, a SpyTag-mScarlet-I (fluorescent protein) and scFv-SpyCatcher fusion proteins were constructed, produced and fused in situ during the assay by spontaneous Tag-Catcher binding. The assay showed an excellent sensitivity with an EC50 of 4.8 ± 0.4 ng mL⁻¹ and a dynamic range from 1.7 ± 0.3 to 13 ± 2 ng mL⁻¹, an inter-day reproducibility of 8.5% and a high selectivity towards HT-2 toxin without cross-reactivity with other Fusarium toxins. The bioassay was applied to the analysis of the toxin in an oat reference material and in oat samples, with a LOD of 0.6 µg kg⁻¹, and the results were validated by analysing a certificate reference material and by HPLC–MS/MS.

One-step extraction and simultaneous quantitative fluorescence immunochromatography strip for AFB1 and Cd detection in grain

AFB₁ and heavy metal Cd are two common pollutants during grain storage. The rapid detection of grains before they enter the granary is particularly important. Hence, rapidly, accurately, and sensitively screening contaminated grains, simplifying the detection process, and reducing detection costs are necessary. In this study, linear ranges of time-resolved fluorescence microsphere - immunochromatographic test strip (TRFM-ICTS) detection were 0.01-30 ng/mL (AFB₁) and 0.01-60 ng/mL (Cd), and the IC₅₀ values were 0.536 ng/mL (AFB₁) and 3.331 ng/mL (Cd). In the TRFM-ICTS sample addition experiment, the recovery rates were all between 90% and 110%. The coefficient of variation was less than 8% in the actual sample detection process of grain. We have established a one-step extraction method for AFB₁ and Cd in grains to achieve simultaneous detection in one extraction. In addition, TRFM-ICTS could be stored for at least 12 months, providing technical support for the realization of commercial production.

A global systematic review and meta-analysis of concentration and prevalence of mycotoxins in birds' egg

In the current study, the concentration and prevalence of birds' egg's mycotoxins among 11 articles (66 studies) based on countries, part of eggs, and type of mycotoxins subgroups were meta-analyses using a random-effect model. The order of mycotoxin according to concentration of mycotoxin was Deoxynivalenol (20.083 μg/kg) > Zearalenone (2.065 μg/kg) > Enniatin (1.120 μg/kg) > Total aflatoxin (0.371 μg/kg) > Beauvericin (0.223 μg/kg) > Ochratoxins (0.087 μg/kg) > Citrinin (0.010 μg/kg). Further, the mycotoxins' concentration in the yolk part (2.070 μg/kg) was higher than the mixed eggs (0.283 μg/kg). The rank order of mycotoxin based on country was China (14.990 μg/kg) > Cameroon (7.594 μg/kg) > Thailand (1.870 μg/kg) > Finland (0.920 μg/kg) > Iran (0.312 μg/kg) > Jordan (0.202 μg/kg) > Belgium (0.183 μg/kg) > Spain ( South Korea ( DON (85.00%) > AFT (20.15%) > OT (16.00%). The overall prevalence of mycotoxin was equal to 29.65%. Also, the concentration of mycotoxins in China and Cameroon was higher than in other countries. Therefore, the monitoring programs to reduce mycotoxins in bird eggs consumed in some countries such as China and Cameroon should be considered.

Prevalence, level and health risk assessment of mycotoxins in the fried poultry eggs from Jordan

In the current study, level and prevalence of deoxynivalenol (DON), aflatoxin B1 (AFB1), zearalenone (ZEN), and ochratoxin A (OTA) in fried poultry eggs in Jordan was investigated. Poultry egg samples (n = 250) were collected from March to September 2017. The level of DON, AFB1, ZEN and OTA in the white and yolk of poultry eggs was measured using LC-MS-MS. The health risk assessment was calculated using Margin of Exposures (MOEs) for AFB1 and OTA and hazard index (HI) for ZEN and DON. The highest prevalence in yolk and white of eggs was related to ZEN (96.56 %) and OTA (97.44 %), respectively. Also, the highest level in white and yolk was related to DON (1.07 μg/kg) and DON (1.65 μg/kg), respectively. Level of DON in the yolk of eggs was significantly higher than white of eggs (P-value < 0.05). Risk assessment indicated that exposed population are at high risk of AFB1 (MOEs < 10,000) in fried poultry eggs.

Alternaria Mycotoxins: An Overview of Toxicity, Metabolism, and Analysis in Food

The genus Alternaria is widely distributed in the environment. Numerous species of the genus Alternaria can produce a variety of toxic secondary metabolites, called Alternaria mycotoxins. In this review, natural occurrence, toxicity, metabolism, and analytical methods are introduced. The contamination of these toxins in foodstuffs is ubiquitous, and most of these metabolites present genotoxic and cytotoxic effects. Moreover, Alternaria toxins are mainly hydroxylated to catechol metabolites and combined with sulfate and glucuronic acid in in vitro arrays. A more detailed summary of the metabolism of Alternaria toxins is presented in this work. To effectively detect and determine the mycotoxins in food, analytical methods with high sensitivity and good accuracy are also reviewed. This review will guide the formulation of maximum residue limit standards in the future, covering both toxicity and metabolic mechanism of Alternaria toxins.

Biosensing based on upconversion nanoparticles for food quality and safety applications

Food safety and quality regulations inevitably call for sensitive and accurate analytical methods to detect harmful contaminants in food and to ensure safe food for the consumer. Both novel and well-established biorecognition elements, together with different transduction schemes, enable the simple and rapid analysis of various food contaminants. Upconversion nanoparticles (UCNPs) are inorganic nanocrystals that convert near-infrared light into shorter wavelength emission. This unique photophysical feature, along with narrow emission bandwidths and large anti-Stokes shift, render UCNPs excellent optical labels for biosensing because they can be detected without optical background interferences from the sample matrix. In this review, we show how this exciting technique has evolved into biosensing platforms for food quality and safety monitoring and highlight recent applications in the field.

Efficacy of Potentially Probiotic Fruit-Derived Lactobacillus fermentum, L. paracasei and L. plantarum to Remove Aflatoxin M1 In Vitro

This study evaluated the efficacy of potentially probiotic fruit-derived Lactobacillus isolates, namely, L. paracasei 108, L. plantarum 49, and L. fermentum 111, to remove aflatoxin M₁ (AFM₁) from a phosphate buffer solution (PBS; spiked with 0.15 µg/mL AFM₁). The efficacy of examined isolates (approximately 10⁹ cfu/mL) as viable and non-viable cells (heat-killed; 100 °C, 1 h) to remove AFM₁ was measured after 1 and 24 h at 37 °C. The recovery of AFM₁ bound to bacterial cells after washing with PBS was also evaluated. Levels of AFM₁ in PBS were measured with high-performance liquid chromatography. Viable and non-viable cells of all examined isolates were capable of removing AFM₁ in PBS with removal percentage values in the range of 73.9–80.0% and 72.9–78.7%, respectively. Viable and non-viable cells of all examined Lactobacillus isolates had similar abilities to remove AFM₁. Only L. paracasei 108 showed higher values of AFM₁ removal after 24 h for both viable and non-viable cells. Percentage values of recovered AFM₁ from viable and non-viable cells after washing were in the range of 13.4–60.6% and 10.9–47.9%, respectively. L. plantarum 49 showed the highest AFM₁ retention capacity after washing. L. paracasei 108, L. plantarum 49, and L. fermentum 111 could have potential application to reduce AFM₁ to safe levels in foods and feeds. The cell viability of examined isolates was not a pre-requisite for their capacity to remove and retain AFM₁.

Penicillium italicum: An Underexplored Postharvest Pathogen

In the agricultural sector, citrus is one of the most important fruit genus in the world. In this scenario, Brazil is the largest producer of oranges; 34% of the global production, and exporter of concentrated orange juice; 76% of the juice consumed in the planet, summing up US$ 6.5 billion to Brazilian GDP. However, the orange production has been considerable decreasing due to unfavorable weather conditions in recent years and the increasing number of pathogen infections. One of the main citrus post-harvest phytopathogen is Penicillium italicum, responsible for the blue mold disease, which is currently controlled by pesticides, such as Imazalil, Pyrimethanil, Fludioxonil, and Tiabendazole, which are toxic chemicals harmful to the environment and also to human health. In addition, P. italicum has developed considerable resistance to these chemicals as a result of widespread applications. To address this growing problem, the search for new control methods of citrus post-harvest phytopathogens is being extensively explored, resulting in promising new approaches such as biocontrol methods as “killer” yeasts, application of essential oils, and antimicrobial volatile substances. The alternative methodologies to control P. italicum are reviewed here, as well as the fungal virulence factors and infection strategies. Therefore, this review will focus on a general overview of recent research carried out regarding the phytopathological interaction of P. italicum and its citrus host.

Mycotoxins Analysis in Cereals and Related Foodstuffs by Liquid Chromatography-Tandem Mass Spectrometry Techniques

In the entire world, cereals and related foodstuffs are used as an important source of energy, minerals, and vitamins. Nevertheless, their contamination with mycotoxins kept special attention due to harmful effects on human health. The present paper was conducted to evaluate published studies regarding the identification and characterization of mycotoxins in cereals and related foodstuffs by liquid chromatography coupled to (tandem) mass spectrometry (LC-MS/MS) techniques. For sample preparation, published studies based on the development of extraction and clean-up strategies including solid-phase extraction, solid-liquid extraction, and immunoaffinity columns, as well as on methods based on minimum clean-up (quick, easy, cheap, effective, rugged, and safe (QuEChERS)) technology, are examined. LC-MS/MS has become the golden method for the simultaneous multimycotoxin analysis, with different sample preparation approaches, due to the range of different physicochemical properties of these toxic products. Therefore, this new strategy can be an alternative for fast, simple, and accurate determination of multiclass mycotoxins in complex cereal samples.

Increase in aflatoxin exposure in two populations residing in East and West Texas, United States

Although aflatoxin (AF) exposure has not been recognized as a major problem in the United States and other developed nations, recent global climate change may have a profound impact on distribution of toxigenic fungi growth and production of AFs in grain and groundnuts. Alterations in the contamination pattern can increase human dietary exposure, and further invoke public health concerns and associated disease risks. In this study, two populations from East and West Texas, known for their high risk of liver cancer, were examined for their AF exposure at three different time periods from 2004 to 2014. Serum samples (n = 1124) were collected from participants recruited for various studies from Bexar County and Lubbock County, TX, over the span of 2004 through 2014. The exposure biomarker, serum AFB₁-lysine adduct, was analyzed by HPLC-FLD and confirmed by LC-MS. Both populations showed a significant increase in detection rate, as well as median levels of serum AFB₁-lysine adduct over time, from 2.35 to 4.34 pg/mg albumin in East Texas (2007-2014), and 0.63-3.98 pg/mg albumin in West Texas (2004-2010). This observed shift in exposure likely represents a shift in the AF contamination pattern in the State of Texas, and may warrant further studies on risk assessment for the potential etiological effects of such increased exposures.

Bioluminescent detection of zearalenone using recombinant peptidomimetic Gaussia luciferase fusion protein

The development of a bioluminescent immunosensor is reported for the determination of zearalenone (ZEA) based on a peptide mimetic identified by phage display. The peptide mimetic GW, with a peptide sequence GWWGPYGEIELL, was used to create recombinant fusion proteins with the bioluminescent Gaussia luciferase (GLuc) that were directly used as tracers for toxin detection in a competitive immunoassay without the need for secondary antibodies or further labeling. The bioluminescent sensor, based on protein G-coupled magnetic beads for antibody immobilization, enabled determination of ZEA with a detection limit of 4.2 ng mL^-1 (corresponding to 420 μg kg^-1 in food samples) and an IC₅₀ value of 11.0 ng mL^-1. The sensor performance was evaluated in spiked maize and wheat samples, with recoveries ranging from 87 to 106% (RSD < 20%, n = 3). Finally, the developed method was applied to the analysis of a naturally contaminated reference matrix material and good agreement with the reported concentrations was obtained.Graphical abstract.

Validation of an UHPLC-MS/MS Method for Simultaneous Analysis of 11 Mycotoxins in Wheat Flour Using Immunoaffinity Column

This study focuses on optimization and validation of an Ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous analysis of 11mycotoxins: Aflatoxins (B₁, B₂, G₁, and G₂), Ochratoxin A, Deoxynivalenol, Fumonisins (B₁ and B₂), Zearalenone, T-2, and HT-2toxin, in wheat matrix. Sample extraction and cleanup procedure is based on a single extraction step using acetonitrile/water/acetic acid mixture (79.5/20/0.5 v/v/v) and rapid clean-up of samples were performed with the Myco6in1⁺ Immunoaffinity column. Electrospray ionization at positive mode was operated to the simultaneously analysis of selected mycotoxins in a single run time of 15 min. Multiple Reaction Monitoring (MRM) mode was selected for quantification and detection of the mycotoxins. The analysis method was validated for selected mycotoxins at different spike levels (2-150 ngg^-1 for AFs, T-2, OTA; 20-1500 ngg^-1 for ZER, HT-2 toxin; and 100-1500 ngg^-1 for DON and FB₁+B₂) in wheat. Calibration curves were plotted based on the area of peak analyte in spike samples. Limits of detection (LOD) ranged from 0.7 to 33.3 ngg^-1 and limits of quantification (LOQ) ranged from 2 to 100 ngg^-1. Recovery values were between 70 and 120% for all the mycotoxins, except for AFG₂ (72-123%) and T-2 toxin (77-122%) with good repeatability. The recoveries and repeatabilities were in accordance with the criteria determined by European Union (EU) Recommendation 519/2014.

Highly sensitive and selective aflatoxin B1 biosensor based on Exonuclease I-catalyzed target recycling amplification and targeted response aptamer-crosslinked hydrogel using electronic balances as a readout

The biosensors based on aptamer based stimuli-responsive hydrogels have the characters of high specificity, good stability, portability. Electronic balance is one of the most accurate equipment and can be reached nearly in all labs. Aflatoxin B₁ (AFB₁) is highly toxic and carcinogenic to humans and animals, it is necessary to develop simple and convenient detection method to apply in resource limited area. In this study, a novel strategy for quantitative detection of AFB₁ has been developed by combining the high selectivity and convenient of target-responsive hydrogel and the simple of using electronic balance as readout devices. The AFB₁ target responsive double crosslinked hydrogel has been constructed using linear hyaluronic acid grafted single-stranded DNA complex as the backbone, AFB₁ aptamer and polyethyleneimine as crosslinkers. And platinum nanoparticles (PtNPs) had been embedded in the hydrogel firstly. The present of AFB₁ can bind with the aptamer with high affinity and cause the releasing of aptamer from hydrogel. The addition of Exo I can specifically recognize and cleave the aptamer in AFB₁-aptamer complex, resulting in the releasing of AFB₁, which can react with the hydrogel again, thereby achieving the target cycle. By this means, the hydrogel will collapse and many pre-embedded PtNPs can be released. The transferring of the released PtNPs to a drainage device which contains H₂O₂ can results in the increasing of the internal pressure since the production of oxygen through the catalytic decomposition of H₂O₂ by PtNPs has low solubility. Which will cause the discharging of water from the system and this can be collected and weighed by an electronic balance easily. The weight of water has a linear relationship with AFB₁ concentration. Under 30 min catalytic time, the linear range is 31.2 μg/kg - 6.2 mg/kg with the detection limit of 9.4 μg/kg (S/N = 3). The proposed method was successfully applied to the detection of AFB₁ in peanut samples.

Indirect Competitive Immunoassay on a Blu-ray Disc for Digitized Quantitation of Food Toxins

We report herein a Blu-ray disc technology enabled immunoassay (namely, assay-on-a-Blu-ray) protocol for the quantitation of food toxins. In particular, commercial Blu-ray discs (BDs) are activated as substrates to create indirect competitive immunoassays with the aid of microfluidic channel plates for the quantitation of aflatoxins; an unmodified Blu-ray drive is employed to read the digitized signal (error counts generated from gold/silver-particle-enhanced binding sites); and a free disc-quality control software is adapted to process the raw data. The performance of this BD-based digital detection platform has been tested for the quantitation of aflatoxin B1 (AFB1) in spiked corn samples and validated with standard high-performance liquid chromatography measurements. The detection limit attained is as low as 0.27 ppb with a dynamic response range up to 200 ppb, which meets the standards established by government agencies worldwide for food products. We truly believe that the application potential of such a BD-technology-based, portable device for multiplex on-site quantitative analysis of food products as well as environmental and biomedical samples in real time is unlimited.

Microfluidic paper device for rapid detection of aflatoxin B1 using an aptamer based colorimetric assay

Contamination of milk by mycotoxins is a serious problem worldwide. Herein, we focused on the detection of aflatoxin B1 (AflB1) using a paper microfluidic device fabricated with specific aptamers as biorecognition elements. The fabrication process resulted in the generation of a leak proof microfluidic device where two zones were designed: control and test. Detection is achieved by color change when aflatoxin reacts with an aptamer followed by salt induced aggregation of gold nanoparticles. Specific aptamers for aflatoxin B1 were immobilized successfully onto the surface of gold nanoparticles. Biophysical characterization of the conjugated AuNPs-aptamer was done by UV-vis spectroscopy, DLS (dynamic light scattering), TEM (transmission electron microscopy). Under optimal conditions, the microfluidic device showed an excellent response for aflatoxin B1 detection in the range of 1 pM to 1 μM with a detection limit of up to 10 nM in spiked samples. Disadvantages associated with conventional techniques of ELISA were overcome by this one step detection technique with low operation cost, simple instrumentation, and user-friendly format with no interference due to chromatographic separation. The developed microfluidic paper-based analytical device (μPAD) can provide a tool for on-site detection of food toxins in less than a minute which is the main requirement for both qualitative and quantitative analysis in food safety and environmental monitoring.

A signal-on electrochemical aptasensor for rapid detection of aflatoxin B1 based on competition with complementary DNA

Aflatoxin B1 (AFB1) is the most toxic mycotoxin, causing harmful effects on human and animal health, and the rapid and sensitive detection of AFB1 is highly demanded. We developed a simple electrochemical aptasensor achieving rapid detection of aflatoxin B1 (AFB1). A short anti-AFB1 aptamer having a methylene blue (MB) redox tag at the 3'-end was immobilized on the surface of a gold electrode. In the absence of AFB1, a complementary DNA (cDNA) strand hybridized with the MB-labeled aptamer, causing MB apart from the electrode surface and low current of MB. In the presence of AFB1, AFB1 competed with the cDNA in the binding to the MB-labeled aptamer, and the aptamer-AFB1 binding caused formation of a hairpin structure, making the MB close to the electrode surface and current of MB increase. Under optimized conditions, we achieved detection of AFB1 over dynamic concentration range of 2 nM-4 μM by using this signal-on electrochemical aptasensor. This method only required a simple 5-min incubation of sample solution prior to rapid electrochemical sensing, more rapid than other electrochemical aptasensors. The sensor could be well regenerated and reused. This sensor allowed to detect AFB1 spiked in 20-fold diluted beer and 50-fold diluted white wine, respectively. It shows potential for detection of AFB1 in wide applications.

Homogeneous Quenching Immunoassay for Fumonisin B1 Based on Gold Nanoparticles and an Epitope-Mimicking Yellow Fluorescent Protein

Homogeneous immunoassays represent an attractive alternative to traditional heterogeneous assays due to their simplicity, sensitivity, and speed. On the basis of a previously identified epitope-mimicking peptide, or mimotope, we developed a homogeneous fluorescence quenching immunoassay based on gold nanoparticles (AuNPs) and a recombinant epitope-mimicking fusion protein for the detection of mycotoxin fumonisin B₁ (FB₁). The fumonisin mimotope was cloned as a fusion protein with a yellow fluorescent protein that could be used directly as the tracer for FB₁ detection without the need of labeling or a secondary antibody. Furthermore, owing to the fluorescence quenching ability of AuNPs, a homogeneous immunoassay could be performed in a single step without washing steps to separate the unbound tracer. The homogeneous quenching assay showed negligible matrix effects in 5% wheat extract and high sensitivity for FB₁ detection, with a dynamic range from 7.3 to 22.6 ng mL^-1, a detection limit of 1.1 ng mL^-1, and IC₅₀ value of 12.9 ng mL^-1, which was significantly lower than the IC₅₀ value of the previously reported assay using the synthetic counterpart of the same mimotope in a microarray format. The homogeneous assay was demonstrated to be specific for fumonisins B₁ and B₂, as no significant cross-reactivity with other mycotoxins was observed, and acceptable recoveries (86% for FB₁ 2000 μg kg^-1 and 103% for FB₁ 4000 μg kg^-1), with relative standard deviation less than 6.5%, were reported from spiked wheat samples, proving that the method could provide a valuable tool for simple analysis of mycotoxin-contaminated food samples.