Immunoaffinity column clean-up prior to thin-layer chromatography for the determination of aflatoxins in various food matrices

Dual modal improved enzyme-linked immunosorbent assay for aflatoxin B1 detection inspired by the interaction of amines with Prussian blue nanoparticles

This work reports an improved enzyme-linked immunosorbent assay (ELISA) via the interaction between prussian blue nanoparticles (PBNPs) and amines for aflatoxin B1 (AFB1) detection. The effect of different amines on the structure and properties of PBNPs was systematically investigated. Amines with pKb < 7, like ethylenediamine (EDA), can decompose structure of PBNPs, leading to the reduction of extinction coefficient and photothermal effect. Whereas, amines with large pKb > 7, such as o-phenylenediamine (OPD), could undergo catalytic oxidation by PBNPs, resulting in the production of fluorescent and colored oxidation products. Accordingly, EDA and OPD were used to construct improved ELISA. Specifically, silica nanoparticles, on which AFB1 aptamer and amino binding agent (ethylenediaminetetraacetic acid disodium salt, EDTA•2Na) were previously assembled via carboxyl-amino linkage, are anchored to microplates by AFB1 and antibody. EDA concentration can be regulated by EDTA•2Na to affect extinction coefficient and photothermal effect of PBNPs, thereby achieving visual colorimetric and portable photothermal signal readout (Model 1). OPD concentration can also be controlled by EDTA•2Na, thus generating colorimetric and ultrasensitive fluorescent signals through PBNPs catalysis (Model 2). The proposed strategy not only opens new avenue for signal readout mode of biosensing, but also provides universal technique for hazards.

Determination of Aflatoxins in Milk by PS-MWCNT/OH Composite Nanofibers Solid-Phase Extraction Coupled with HPLC-FLD

In this work, a sensitive analytical method based on packed-nanofiber solid-phase extraction (PFSPE), after derivatization with trichloroacetic acid and high-performance liquid chromatography with a fluorescence detector (HPLC-FLD), has been established for the determination of aflatoxins (AFs) in milk. Polystyrene polymeric multi-walled carbon nanotube (PS-MWCNT/OH) composite nanofibers were fabricated by electrospinning and used to prepare homemade extraction columns. The extraction efficiency of the HPLC-FLD analysis method was sufficiently investigated and validated. After the implementation of optimal conditions, all of the analytes were separated efficiently and the components of the milk matrix did not disturb the determination. The obtained linear ranges of the calibration curves were 0.2-20 ng/mL for AFTB1 and AFTG2, 0.1-10 ng/mL for AFTB2, and 0.4-40 ng/mL for AFTG1. The recoveries ranged between 80.22% and 96.21%. The relative standard deviations (RSDs) for the intra-day and inter-day results ranged from 2.81-6.43% to 3.42-7.75%, respectively. Generally, 11 mg of sorbent and 200 μL of elution solvent were used to directly extract all of the AFs from the milk matrix. Reported herein is the first utilization of PS-MWCNT/OH-PFSPE HPLC-FLD to simultaneously analyze the occurrence of aflatoxins in milk.

Aflatoxin detection technologies: recent advances and future prospects

Aflatoxins have posed serious threat to food safety and human health. Therefore, it is important to detect aflatoxins in samples rapidly and accurately. In this review, various technologies to detect aflatoxins in food are discussed, including conventional ones such as thin-layer chromatography (TLC), high performance liquid chromatography (HPLC), enzyme linked immunosorbent assay (ELISA), colloidal gold immunochromatographic assay (GICA), radioimmunoassay (RIA), fluorescence spectroscopy (FS), as well as emerging ones (e.g., biosensors, molecular imprinting technology, surface plasmon resonance). Critical challenges of these technologies include high cost, complex processing procedures and long processing time, low stability, low repeatability, low accuracy, poor portability, and so on. Critical discussion is provided on the trade-off relationship between detection speed and detection accuracy, as well as the application scenario and sustainability of different technologies. Especially, the prospect of combining different technologies is discussed. Future research is necessary to develop more convenient, more accurate, faster, and cost-effective technologies to detect aflatoxins.

Determination of aflatoxin B1 by novel nanofiber-packed solid-phase extraction coupled with a high performance liquid chromatography-fluorescence detector

A novel analytical proposal based on nanofiber-packed solid-phase extraction coupled with high performance liquid chromatography-fluorescence detector (HPLC-FLD) has been successfully developed for determining aflatoxin B1 (AFB1) in foods. Four types of nanofibers, including polystyrene (PS) nanofibers, polypyrrole (PPY) nanofibers, polystyrene-acrylic resin (PS-AR) nanofibers, and polystyrene-polyvinyl pyrrolidone (PS-PVP) nanofibers, were fabricated by electrospinning and utilized to prepare a home-made extraction device. In this study, the factors of different fibers, namely, fiber dosage, pH of extraction solution, type of salt ion, concentration of salt ion, and volume of the eluent were optimized. Under optimized conditions, the method showed good linearity in the range of 0.1-40 ng mL^-1 with a correlation coefficient greater than 0.999 and good inter-day accuracy (90.8-112.7% recovery) and precision (1.8-3.6% intra-day RSDs, 2.6% inter-day RSD), and the limit of detection (LOD) was 0.05 ng mL^-1. Due to its cost-effective, time-saving, environmentally friendly, and simple performance, it has the potential to be utilized to determine aflatoxins in complicated matrices.

Study on Molecularly Imprinted Polymers Obtained Sonochemically for the Determination of Aflatoxins in Food

Aflatoxins (AFs) are fungi secondary metabolites produced by the Aspergillus family. These compounds can enter the food chain through food contamination, representing a risk to human health. Commercial immunoaffinity columns are widely used for the extraction and cleanup of AFs from food samples; however, their high cost and large solvent consumption create a need for alternative strategies. In this work, an alternative strategy for producing molecularly imprinted polymers (MIPs) was proposed to extract aflatoxins AFB1, AFB2, AFG1, and AFG2 from complex food samples, using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The MIPs were synthesized via a low-cost and rapid (5 min) sonochemical free-radical polymerization, using 1-hydroxy-2-naphthoic acid as a dummy template. MIPs-based solid phase extraction performance was tested on 17 dietary supplements (vegetables, fruits, and cereals), obtaining appreciable recovery rates (65-90%) and good reproducibility (RSD ≤ 6%, n = 3); the selectivity towards other mycotoxins was proved and the data obtained compared with commercial immunoaffinity columns. The proposed strategy can be considered an alternative affordable approach to the classical immunoaffinity columns, since it is more selective and better performing.

Structure Elucidation and Toxicity Analysis of the Byproducts Formed after Biodegradation of Aflatoxins B1 and B2 Using Extracts of Mentha arvensis

The aqueous extracts of leaves and shoots of Mentha arvensis were checked for their potential to biodegrade aflatoxin B1 and B2 (AFB1; 100 µg/L and AFB2; 50 µg/L) through in vitro assays. Overall, the results showed that leaf extract degrades aflatoxins more efficiently than the shoot extract. First, the pH, temperature and incubation time were optimized for maximum degradation by observing this activity at different temperatures between 25 and 60 °C, pH between 2 and 10 and incubation time from 3 to 72 h. In general, an increase in all these parameters significantly increased the percentage of biodegradation. In vitro trials on mature maize stock were performed under optimized conditions, i.e., pH 8, temperature 30 °C and an incubation period of 72 h. The leaf extract resulted in 75% and 80% biodegradation of AFB1 and AFB2, respectively. Whereas the shoot extract degraded both toxins up to 40–48%. The structural elucidation of degraded toxin products by LCMS/MS analysis showed seven degraded products of AFB1 and three of AFB2. MS/MS spectra showed that most of the products were formed by the loss of the methoxy group from the side chain of the benzene ring, the removal of the double bond in the terminal furan ring and the modification of the lactone group, indicating less toxicity compared to the parent compounds. The degraded products showed low toxicity against brine shrimps, confirming that M. arvensis leaf extract has significant potential to biodegrade aflatoxins.

An In Situ Generated Prussian Blue Nanoparticle-Mediated Multimode Nanozyme-Linked Immunosorbent Assay for the Detection of Aflatoxin B1

This work aims to develop a novel multimode (photothermal/colorimetric/fluorescent) nanozyme-linked immunosorbent assay (NLISA) based on the in situ generation of Prussian blue nanoparticles (PBNPs) on the surface of magnetic nanoparticles (MNPs). Being considered the most toxic among the mycotoxins, aflatoxin B1 (AFB1) was chosen as the proof-of-concept target. In this strategy, MNPs, on which an AFB1 aptamer was previously assembled via streptavidin-biotin linkage, are anchored to 96-well plates by AFB1 and antibody. In the presence of HCl and K₄Fe(CN)₆, PBNPs formed in situ on the MNP surface, thereby achieving photothermal and colorimetric signal readout due to their photothermal effect and intrinsic peroxidase-like activity. Based on fluorescence quenching by MNPs, Cy5 fluorescence was recovered by the in situ generation of PBNPs to facilitate ultrasensitive fluorescence detection. Photothermal and colorimetric signals allow portable/visual point-of-care testing, and fluorescent signals enable accurate determination with a detection limit of 0.54 fg/mL, which is 6333 and 28 times lower than those of photothermal and colorimetric analyses, respectively. We expect that this proposed multimode NLISA can not only reduce the false-positive/negative rates through the multisignal crossdetection in AFB1 monitoring but also provide a universal way of sophisticated instrumentation-free, easy-to-use, cost-effective, and highly sensitive detection of other food hazards.

Pressure/colorimetric dual-readout immunochromatographic test strip for point-of-care testing of aflatoxin B1

Immunochromatographic test strip (ITS) for point-of-care testing (POCT) has attracted prominent attention due to the advantages including rapid response, low cost and good portability. Here, we developed a sensitive ITS for detecting aflatoxin B₁ (AFB₁) by using dendritic platinum nanoparticles (DPNs) as novel pressure/colorimetric dual-readout probes. DPNs-labeled antibody of AFB₁ were used as the signal tracer of the immunochromatographic process. After 10-min competitive immunoreaction, black color appeared on the test line of ITS due to the accumulation of DPNs, which was observed visually as a colorimetric readout for qualitation purpose. Furthermore, DPNs with peroxidase-like activity caused decomposition of hydrogen peroxide aqueous solution to produce pressure change signal in vials, which was detected by a hand-held pressure meter for quantitation purpose. With the pressure readout mode, the detection range was 0.05-10 ng mL^-1, and the detection limit was 0.03 ng mL^-1 (S/N = 3) for AFB₁. The proposed ITS was successfully utilized for detecting AFB₁ in herbal medicine samples, and the acceptable recoveries of 93.77-114.09% indicated the reliability for real sample detection. It provides a new avenue for POCT with great application potential in various area including drug and food quality control, pollutants monitoring as well as medical diagnosis.

Identification of degradation products of aflatoxin B1 and B2 resulting after their biodetoxification by aqueous extracts of Acacia nilotica

Contamination of food and feed items with mycotoxins causes extensive economic damage. It is therefore important to explore environmentally friendly approaches to manage these toxins with less drawbacks. Phytochemicals can provide a safe alternative to synthetic chemicals. This study was designed to investigate the detoxification potential of water-based extracts of Acacia nilotica against aflatoxins B1 and B2. First trials were carried out to standardise temperature, pH and incubation time for biodetoxification in spiked maize. A significant percentage of detoxification was observed under all tested conditions, showing an increasing detoxifying potential with an increase in all three parameters. Leaf extract was found to be more effective than shoot extract. Leaf extract resulted in 86-90% detoxification of both aflatoxin B1 and B2 when incubated for 72 h at 60 °C and pH 10. To avoid the detrimental effects of very high temperature and pH, experiments on spiked maize were conducted at 30 °C and pH 8. A significant detoxification of 82-83% was recorded during trials with spiked maize. MS/MS analyses showed conversion of aflatoxins B1 into seven and aflatoxins B2 into two new compounds. Most of the compounds were formed due to the removal of the double bond in the terminal furan ring and modification of the lactone group, indicating less toxicity as compared to the parent compounds. Decontamination and reduction in toxicity of treated aflatoxins was corroborated by a brine shrimps bioassay.

A Review: Sample Preparation and Chromatographic Technologies for Detection of Aflatoxins in Foods

As a class of mycotoxins with regulatory and public health significance, aflatoxins (e.g., aflatoxin B1, B2, G1 and G2) have attracted unparalleled attention from government, academia and industry due to their chronic and acute toxicity. Aflatoxins are secondary metabolites of various Aspergillus species, which are ubiquitous in the environment and can grow on a variety of crops whereby accumulation is impacted by climate influences. Consumption of foods and feeds contaminated by aflatoxins are hazardous to human and animal health, hence the detection and quantification of aflatoxins in foods and feeds is a priority from the viewpoint of food safety. Since the first purification and identification of aflatoxins from feeds in the 1960s, there have been continuous efforts to develop sensitive and rapid methods for the determination of aflatoxins. This review aims to provide a comprehensive overview on advances in aflatoxins analysis and highlights the importance of sample pretreatments, homogenization and various cleanup strategies used in the determination of aflatoxins. The use of liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE) and immunoaffinity column clean-up (IAC) and dilute and shoot for enhancing extraction efficiency and clean-up are discussed. Furthermore, the analytical techniques such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), capillary electrophoresis (CE) and thin-layer chromatography (TLC) are compared in terms of identification, quantitation and throughput. Lastly, with the emergence of new techniques, the review culminates with prospects of promising technologies for aflatoxin analysis in the foreseeable future.

Recent Advances in the Aptamer-Based Electrochemical Biosensors for Detecting Aflatoxin B1 and Its Pertinent Metabolite Aflatoxin M1

The notable toxicological impacts of aflatoxin B1 (AFB1) and its main metabolite, aflatoxin M1 (AFM1), on human being health make the evaluation of food quality highly significant. Due to the toxicity of those metabolites-even very low content in foodstuffs-it is crucial to design a sensitive and reliable procedure for their detection. Electrochemical aptamer-based biosensors are considered the most encouraging option, based on multi-placed analysis, rapid response, high sensitivity and specificity. The present review specifically emphasizes the potential utilization of the electrochemical aptasensors for determining the AFM1 and AFB1 with different electrodes.

Current research and prevention of aflatoxins in China

Since their discovery in the 1960s, aflatoxins were found to have a considerable impact on the health of humans and animals as well as the country’s economy and international trade. Aflatoxins are often found in nuts, cereals and animal feeds, which has a significant danger to the food industry. Over the years, several steps have been undertaken worldwide to minimise their contamination in crops and their exposure to humans and animals. China is one of the largest exporters and importers of food and animal feed. As a result, many studies have been carried out in China related to aflatoxins, including their distribution, pollution, detection methods, monitoring, testing and managing. Chinese scientists studied aflatoxins in microbiological, toxicological, ecological effects as well as policies relating to their controlling. China has thus put into practice a number of strategies aiming at the prevention and control of aflatoxins in order to protect consumers and ensure a safe trade of food and feed, and the status and enlargement of these strategies are very important and useful for many consumers and stakeholders in China. Therefore, this article aims at the detriment assessments, regulations, distribution, detection methods, prevention and control of aflatoxins in China. It equally provides useful information about the recent safety management systems in place to fight the contamination of aflatoxins in food and feed in China.

Alkaline Hydrolysis Behavior of Metal-Organic Frameworks NH2-MIL-53(Al) Employed for Sensitive Immunoassay via Releasing Fluorescent Molecules

Nanosized metal-organic frameworks (MOFs) NH₂-MIL-53(Al) were synthesized from 2-aminoterephthalic acid (NH₂·H₂BDC) and AlCl₃ by a facile hydrothermal method. The synthesized MOFs displayed good stability and a uniform particle size in a netural medium and were hydrolyzed in alkaline medium to release a large amount of fluorescent ligand NH₂·H₂BDC. Therefore, they can act as large-capability nanovehicles to load signal molecules for investigating various biorecognition events. In this work, based on the alkaline hydrolysis behavior of MOFs NH₂-MIL-53(Al), a sensitive immunoassay method was developed for the detection of aflatoxin B₁ (AFB₁) by employing them as fluorescent signal probes. With a competitive immunoassay mode on microplate, AFB₁ can be detected within a linear range of 0.05-25 ng mL^-1. The method was successfully employed to detect AFB₁ spiked in Job tears, Polygala tenuifolia and with acceptable recovery values of 83.00-114.00%. The detection results for moldy Fructus xanthii displayed an acceptable agreement with those from the high-performance liquid chromatography method, with relative errors of -14.21 to 3.49%. With the merits of high sensitivity, facile manipulation, and ideal reliability, the approach can also be extended to other areas such as aptasensor and receptor-binding assay.

High-performance liquid chromatography and Enzyme-Linked Immunosorbent Assay techniques for detection and quantification of aflatoxin B1 in feed samples: a comparative study

OBJECTIVE

Comparison was done between high-performance liquid chromatography (HPLC) and a competitive enzyme-linked immunosorbent assay (ELISA) for detection and quantification of aflatoxin B₁ (AFB₁) in feed samples. The two procedures were standardized and validated before the actual experiment. Five concentrations (0, 5, 10, 20 and 30 ppb) of feed samples were used for both methods. For the HPLC technique, the samples were extracted in acetonitrile/water (90/10) solution, cleaned-up using solid phase extraction (SPE) column, and derivatized by water/trifluoroacetic acid/glacial acetic acid (35/10/5) solution before instrument analysis. The samples were extracted in 70% methanol for the ELISA technique.

RESULTS

The two tests showed very strong linearity with correlation coefficient value of > 0.99 using standard solutions. The mean recovery rate was 92.42% (with relative standard deviation (RSD) of 5.97) and 75.64% (RSD = 34.88) for HPLC and ELISA, respectively. There was no statistically significant difference in recovery rate between the two methods. There was a positive correlation (r = 0.84) between them which indicated that the two techniques can be used to detect and quantify aflatoxin B₁ in feed samples. However, there were variations among replicates for the ELISA method, which shows that this method is more applicable for screening purposes.

A rapid fluorometric method for determination of aflatoxin B1 in plant-derived food by using a thioflavin T-based aptasensor

A fluorometric aptamer-based method is described for the determination of aflatoxin B₁ (AFB₁). The fluorescent dye thioflavin T (ThT) forms a complex with the aptamer against AFB₁ (aptamer/ThT), and the fluorescence of the complex is strongly enhanced. On addition of AFB₁, it will bind to the aptamer and release ThT. The fluorescence of free ThT is much weaker. The fluorescence of the system, best measured at excitation/emission wavelengths of 440/487 nm, drops gradually in the AFB₁ concentration range from 0.2 to 200 ng·mL^-1, exhibiting good linearity. The detection limits are 0.2 ng·mL^-1 in buffer solution, and 1 ng·mL^-1 when applied to plant-derived food. The recovery of AFB₁ from spiked foodstuff ranges from 74.7% to 121%. The assay can be performed within 20 min. Graphical abstract Schematic presentation of label-free thioflavin T (ThT)-based fluorescence aptasensor using aflatoxin B₁(AFB₁) aptamer/ThT G-quadruplex complex and the AFB1 aptamer/AFB1 complex fluorescent signal system for the rapid and sensitive detection of AFB1 in soy sauce, spirits, rice, corn and peanuts.

Simultaneous determination of trace Aflatoxin B1 and Ochratoxin A by aptamer-based microchip capillary electrophoresis in food samples

An aptamer-based microchip capillary electrophoresis coupled with laser induced fluorescence (MCE-LIF) detection method for fast determination of Aflatoxin B₁ (AFB₁) and Ochratoxin A (OTA) was developed. Aptamers that are specific to these two mycotoxins were first hybridized with their aptamer complementary oligonucleotides. The double strand DNA that comes in contact with mycotoxin-containing environment would be unwound into separate aptamer-mycotoxin complex and aptamer complementary single strand. Different types of oligonucleotides can be separated in MCE and detected under the aid of fluorescent dye SYBR gold in LIF detection unit. Under the optimal conditions, on-chip aptamer-mycotoxin conjugates analysis was achieved within 3 min with extremely low LODs (0.026 ng/mL for AFB₁ and 0.021 ng/mL for OTA). Specificity study indicated that other major mycotoxins would not cross-react with these two aptamers, demonstrating the good selectivity of the proposed method. Quantification of trace AFB₁ and OTA in real food samples was carried out and satisfactory recoveries were obtained. It is demonstrated that this method is fast, facile and specific for Simultaneous determination of trace AFB₁ and OTA from foodstuffs.

Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B₁, B₂, G₁, G₂ were extracted from samples by using methanol/water (70:30, v/v) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity (R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15-0.65 and 0.53-2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2-3.6%), and accuracy (recovery rates of 86.0-102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B₁ (AFB₁) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.

Rapid characterization of trace aflatoxin B1 in groundnuts, wheat and maize by dispersive liquid-liquid microextraction followed by direct electrospray probe tandem mass spectrometry

RATIONALE

Aflatoxins are poisonous and cancer-related chemical compounds commonly found in crops and plants. Aflatoxin B₁ is the most toxic compound among aflatoxins and has been classified as group 1 carcinogenic to humans, especially in liver cancer. Herein, an ambient mass spectrometric method was developed for rapid characterization of trace aflatoxin B₁ in peanuts.

METHODS

Direct electrospray probe tandem mass spectrometry (DEP-MS/MS) was used to detect aflatoxin B₁ in peanuts. To avoid the matrix effect, the aflatoxin B₁ in the samples was extracted and concentrated by dispersive liquid-liquid microextraction. The mass spectrometer was operated in the positive ion mode to monitor the intact molecular ion (m/z 313, MH⁺ ) and product ion (m/z 241) of aflatoxin B₁ using multiple reaction monitoring.

RESULTS

Since no clean-up procedure of the sample was required, the sampling step and the subsequent mass spectrometric detection of the aflatoxin B₁ was completed in less than 5 min. The limit of detection of aflatoxin B₁ is at the sub-ppb level. The results obtained by DEP-MS/MS were also validated by liquid chromatography/tandem mass spectrometry (LC/MS/MS). Recovery of aflatoxin B₁ in the sample was evaluated by analyzing spiked aflatoxin B₁ with LC/MS/MS to be 85% and DEP-MS/MS to be 84%.

CONCLUSIONS

DEP-MS/MS combined with a simple dispersive liquid-liquid microextraction procedure was successfully used for the quantitative analysis of AFB₁ in nut samples. Due to its high efficiency, it is promising in providing important toxicological information for food safety in the real world. Copyright © 2017 John Wiley & Sons, Ltd.

Development of Methods for Determination of Aflatoxins

Aflatoxins can cause damage to the health of humans and animals. Several institutions around the world have established regulations to limit the levels of aflatoxins in food, and numerous analytical methods have been extensively developed for aflatoxin determination. This review covers the currently used analytical methods for the determination of aflatoxins in different food matrices, which includes sampling and sample preparation, sample pretreatment methods including extraction methods and purification methods of aflatoxin extracts, separation and determination methods. Validation for analysis of aflatoxins and safety considerations and precautions when doing the experiments are also discussed.

Quantitative Scrutinization of Aflatoxins in Different Spices from Pakistan

The current research work aimed to access the contamination level of aflatoxins B1, B2, G1, and G2 in the household spices that are widely consumed in huge amounts. 200 different spice samples, 100 packed and 100 unpacked, were analyzed for the aflatoxins profile by HPLC with an incidence of 61.5% contamination out of which 53.66% samples exceed the EU limit. The results disclosed that the unpacked samples are more contaminated as compared to the packed samples except for white cumin seeds. Among packed and unpacked samples of spices, the maximum value of aflatoxins was detected in fennel, that is, 27.93 μg/kg and 67.04 μg/kg, respectively. The lowest concentration of aflatoxin was detected in cinnamon in packed form (0.79 μg/kg) and in the unpacked samples of white cumin seeds which is 1.75 μg/kg. Caraway seeds and coriander in its unpacked form showed positive results whereas black pepper (packed and unpacked) was found free from aflatoxins. This is the first report on the occurrence of aflatoxins in packed and unpacked samples of spices from Pakistan. To ensure safe consumption of spices, there should be constant monitoring of aflatoxin and more studies need to be executed with the intention of preventing mycotoxin accretion in this commodity.

Structural Analysis and Biological Toxicity of Aflatoxins B1 and B2 Degradation Products Following Detoxification by Ocimum basilicum and Cassia fistula Aqueous Extracts

This study showed the comparison between Ocimum basilicum and Cassia fistula (leaves and branch) aqueous extracts for their ability to detoxify of aflatoxins B1 and B2 (AFB1; 100 μg L(-1) and AFB2; 50 μg L(-1)) by In Vitro assays and decontamination studies. Results indicated that O. basilicum leaves extract was found to be highly significant (P < 0.05) in degrading AFB1 and AFB2, i.e., 90.4 and 88.6%, respectively. However, O. basilicum branch, C. fistula leaves and branch extracts proved to be less efficient in degrading these aflatoxins, under optimized conditions, i.e., pH 8, temperature 30°C and incubation period of 72 h. Moreover the antifungal activity of these plants extracts were also tested. The findings depicted that O. basilicum leaves extract showed maximum growth inhibition of aflatoxigenic isolates, i.e., 82-87% as compared to other tested plants extracts. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that nine degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that O. basilicum leaves extract can be used as an effective tool for the detoxification of aflatoxins.

Structural Elucidation and Toxicity Assessment of Degraded Products of Aflatoxin B1 and B2 by Aqueous Extracts of Trachyspermum ammi

In this study aqueous extract of seeds and leaves of Trachyspermum ammi were evaluated for their ability to detoxify aflatoxin B1 and B2 (AFB1; 100 μg L(-1) and AFB2; 50 μg L(-1)) by in vitro and in vivo assays. Results indicated that T. ammi seeds extract was found to be significant (P < 0.05) in degrading AFB1 and AFB2 i.e., 92.8 and 91.9% respectively. However, T. ammi leaves extract proved to be less efficient in degrading these aflatoxins, under optimized conditions i.e., pH 8, temperature 30°C and incubation period of 72 h. The structural elucidation of degraded toxin products by LCMS/MS analysis showed that eight degraded products of AFB1 and AFB2 were formed. MS/MS spectra showed that most of the products were formed by the removal of double bond in the terminal furan ring and modification of lactone group indicating less toxicity as compared to parent compounds. Brine shrimps bioassay further confirmed the low toxicity of degraded products, showing that T. ammi seeds extract can be used as an effective tool for the detoxification of aflatoxins.

Recent trends in rapid environmental monitoring of pathogens and toxicants: potential of nanoparticle-based biosensor and applications

Of global concern, environmental pollution adversely affects human health and socioeconomic development. The presence of environmental contaminants, especially bacterial, viral, and parasitic pathogens and their toxins as well as chemical substances, poses serious public health concerns. Nanoparticle-based biosensors are considered as potential tools for rapid, specific, and highly sensitive detection of the analyte of interest (both biotic and abiotic contaminants). In particular, there are several limitations of conventional detection methods for water-borne pathogens due to low concentrations and interference with various enzymatic inhibitors in the environmental samples. The increase of cells to detection levels requires long incubation time. This review describes current state of biosensor nanotechnology, the advantage over conventional detection methods, and the challenges due to testing of environmental samples. The major approach is to use nanoparticles as signal reporter to increase output rather than spending time to increase cell concentrations. Trends in future development of novel detection devices and their advantages over other environmental monitoring methodologies are also discussed.

A fabricated electro-spun sensor based on Lake Red C pigments doped into PAN (polyacrylonitrile) nano-fibers for electrochemical detection of Aflatoxin B1 in poultry feed and serum samples

The aim of this work was to fabricate a novel nano-fiber modified electrode, involving Lake Red C (LRC) pigments doped into electrospun polyacrylonitrile (PAN) fibrous films.

Filamentous Fungi and Mycotoxins in Cheese: A Review

Important fungi growing on cheese include Penicillium, Aspergillus, Cladosporium, Geotrichum, Mucor, and Trichoderma. For some cheeses, such as Camembert, Roquefort, molds are intentionally added. However, some contaminating or technological fungal species have the potential to produce undesirable metabolites such as mycotoxins. The most hazardous mycotoxins found in cheese, ochratoxin A and aflatoxin M1, are produced by unwanted fungal species either via direct cheese contamination or indirect milk contamination (animal feed contamination), respectively. To date, no human food poisoning cases have been associated with contaminated cheese consumption. However, although some studies state that cheese is an unfavorable matrix for mycotoxin production; these metabolites are actually detected in cheeses at various concentrations. In this context, questions can be raised concerning mycotoxin production in cheese, the biotic and abiotic factors influencing their production, mycotoxin relative toxicity as well as the methods used for detection and quantification. This review emphasizes future challenges that need to be addressed by the scientific community, fungal culture manufacturers, and artisanal and industrial cheese producers.

Natural occurrence, analysis, and prevention of mycotoxins in fruits and their processed products

Mycotoxins are small toxic chemical products formed as the secondary metabolites by fungi that readily contaminate foods with toxins in the field or after harvest. The presence of mycotoxins, such as aflatoxins, ochratoxin A, and patulin, in fruits and their processed products is of high concern for human health due to their properties to induce severe acute and chronic toxicity at low-dose levels. Currently, a broad range of detection techniques used for practical analysis and detection of a wide spectrum of mycotoxins are available. Many analytical methods have been developed for the determination of each group of these mycotoxins in different food matrices, but new methods are still required to achieve higher sensitivity and address other challenges that are posed by these mycotoxins. Effective technologies are needed to reduce or even eliminate the presence of the mycotoxins in fruits and their processed products. Preventive measures aimed at the inhibition of mycotoxin formation in fruits and their processed products are the most effective approach. Detoxification of mycotoxins by different physical, chemical, and biological methods are less effective and sometimes restricted because of concerns of safety, possible losses in nutritional quality of the treated commodities and cost implications. This article reviewed the available information on the major mycotoxins found in foods and feeds, with an emphasis of fruits and their processed products, and the analytical methods used for their determination. Based on the current knowledge, the major strategies to prevent or even eliminate the presence of the mycotoxins in fruits and their processed products were proposed.