Detection Of Aflatoxins Research Articles

Pixel-level rapid detection of aflatoxin B1 based on 1D-modified temporal convolutional network and hyperspectral imaging

Aflatoxin is a virulent toxic and cancerogenic substance, and it is widespread on the peanuts surface. This study uses a one-dimensional modified temporal convolutional network (1D-modified TCN) to detect aflatoxins at the pixel level with hyperspectral images. Then, the robustness of this method was verified from compressed image size and reduced spectral acquisition points, and feasible strategies were provided for accelerating model optimization training. The experimental results indicate that 1D-modified TCN is best under the image size of 63×47, the model training accuracy was 99.60 %, and the test accuracy was 99.26 %. Finally, the detection results of the four one-dimensional network models were visualized on three new peanut kernels. This method has improved the accuracy of aflatoxin detection and it will quickly promote the design and development of intelligent devices in detecting aflatoxin.

A stem-loop like aptasensor for sensitive detection of aflatoxin based on graphene oxide/AuNPs nanocomposite platform

Aflatoxin as the potent carcinogenic mycotoxin had been received great attention for detection in food industry and safety. Due to low quantity of aflatoxin in food samples, there is a need to develop a sensitive method toward its detection. In the present study, an aflatoxin B1 (AFB1) specific aptasensor with internal complementary sequence was developed for detection of AFB1. The FAM-functionalized aptamer was deposited on the surface of graphene oxide decorated with gold nanoparticles (GO/AuNPs) and following formation of heteroduplex stem-loop structure led to fluorescence quenching of FAM-labeled aptamer. After incubation of proposed aptasensor with AFB1, the aptamer-AFB1 complex resulted to denaturation in stem-loop structure of aptamer which caused restoration of single strand aptamer and recovery of fluorescence. The assay showed a convenient detection response in the range of 0.5-20 pg/mL with a very low detection limit (0.1 pg/mL) and it was highly selective for AFB1 over other mycotoxins.

Aflatoxin tests in herbal products and its quantification: Latest updates.

Aflatoxin is naturally occurring mycotoxins produced by fungi. The existence of aflatoxin in herbal medicines is a well-known issue. The detection of aflatoxin with good sensitivity and also that is reliable in complex matrices like herbs usually necessitates difficult processes and powerful detection instrument in preparation of sample. This study investigated the global occurrence of aflatoxin contamination herbal products. This article pivots on key breakthroughs in preparation of sample and its importance in analytical technology. Studies from published studies were screened to determine the general level of aflatoxin contamination. The countries involved were Malaysia, Indonesia, Kenya, Brazil, Nigeria, Thailand, South Africa, and Morocco. This review also includes recent studies on the development and application of screening assays such as lateral flow immunoassays, enzyme-linked immunosorbent assays, aptamer-based lateral flow assays, and cytometric bead arrays, as well as traditional chromatographic techniques for aflatoxin qualification or quantitation. The current study looks at aflatoxin contamination of key herbal drug raw material, which are frequently used in the production of numerous herbal pharmaceuticals. Contamination of aflatoxin might occur in herbal products if the ingredients such as medicinal herbs and plants that are used in manufacturing of herbal products are not dried thoroughly or stored inappropriately after preparation.

Wash-free electrochemical aptasensor for the detection of aflatoxins by the signal amplification of ferrocene-capped gold nanoparticles

Wash-free electrochemical aptasensor for the detection of aflatoxins by the signal amplification of ferrocene-capped gold nanoparticles

The presence and transfer characteristics of aflatoxins in medicinal herbs: From raw materials to edible dispensing granules.

In this study, a sensitive and accurate immunoaffinity columns coupled with high-performance liquid chromatography method was established to monitor the presence of aflatoxins-aflatoxin B1 , aflatoxin B2 , aflatoxin G1 , and aflatoxin G2 -in different medicinal herbs. The proposed method was found to be suitable for the detection of aflatoxins in eight kinds of herbs and their corresponding granules. Two batches of Arecae semen were positive for aflatoxins, with high residue levels of different aflatoxins. To better understand the presence and transfer of aflatoxins during the formulation of dispensing granules from the herbs, the aflatoxins-free herbs were artificially inoculated with Aspergillus flavus to explore aflatoxins production. Both aflatoxin B1 and aflatoxin B2 were detected in all inoculated samples, while aflatoxin G2 was only detected in Astragali radix samples. Additionally, the presence of aflatoxin B1 was extremely high compared to other aflatoxins. More specifically, the transfer rate of the aflatoxin B1 and the total aflatoxins from original herbs to granules were both approximately 40%. These findings indicated that the preparation of herbs into dispensing granules reduced the content of aflatoxins. The high-level presence of aflatoxins in inoculated herbs indicated that attention is needed to the safety of A. flavus-contaminated herbs.

Rapid Detection of Aspergillus flavus and Quantitative Determination of Aflatoxin B1 in Grain Crops Using a Portable Raman Spectrometer Combined with Colloidal Au Nanoparticles.

Aspergillus flavus and Aflatoxins in grain crops give rise to a serious threat to food security and cause huge economic losses. In particular, aflatoxin B1 has been identified as a Class I carcinogen to humans by the International Agency for Research on Cancer (IARC). Compared with conventional methods, Surface-Enhanced Raman Scattering (SERS) has paved the way for the detection of Aspergillus flavus and Aflatoxins in grain crops as it is a rapid, nondestructive, and sensitive analytical method. In this work, the rapid detection of Aspergillus flavus and quantification of Aflatoxin B1 in grain crops were performed by using a portable Raman spectrometer combined with colloidal Au nanoparticles (AuNPs). With the increase of the concentration of Aspergillus flavus spore suspension in the range of 102–108 CFU/mL, the better the combination of Aspergillus flavus spores and AuNPs, the better the enhancement effect of AuNPs solution on the Aspergillus flavus. A series of different concentrations of aflatoxin B1 methanol solution combined with AuNPs were determined based on SERS and their spectra were similar to that of solid powder. Moreover, the characteristic peak increased gradually with the increase of concentration in the range of 0.0005–0.01 mg/L and the determination limit was 0.0005 mg/L, which was verified by HPLC in ppM concentration. This rapid detection method can greatly shorten the detection time from several hours or even tens of hours to a few minutes, which can help to take effective measures to avoid causing large economic losses.

Programmable Analytical Feature of Ratiometric Electrochemical Biosensor by Alternating the Binding Site of Ferrocene to DNA Duplex for the Detection of Aflatoxin B1†

Comprehensive SummaryRatiometric biosensor is among the promising strategies for the advanced analysis; its applicability in multiple scenarios, however, is seriously limited for the fixed analytical feature. Here, we reported ratiometric electrochemical biosensors with programmable analytical feature by alternating the binding site of ferrocene (Fc) to DNA duplex for the detection of aflatoxin B1 (AFB1). DNA duplex was synthesized with AFB1 aptamer and its complementary DNA (cDNA) with Fc molecular tagged on aptamer or cDNA. For analysis, aptamer‐AFB1 complex stripped from the electrode, and free cDNA triggered hybridization chain reaction to produce double‐stranded DNA for methylene blue (MB) absorption. In this way, redox currents of Fc (IFc) and absorbed MB (IMB) at the electrode were collected to produce the ratiometric signal of IMB/IFc as a yardstick for AFB1. When Fc was tagged on aptamer, IFc decreased with higher concentration of AFB1 (cAFB1), the resultant biosensor allowed detection with an On/Off (IMB/IFc) mode; when Fc was tagged on cDNA, IFc kept constant as cAFB1 varying, offering an On/Constant (IMB/IFc) mode for the detection. Consequently, biosensor with On/Off mode showed a linear range of 0.1—100 pg/mL with a limit of detection (LOD) of 0.0650 pg/mL, while biosensor with On/Constant mode offered a wider linear rang of 1—10000 pg/mL but a relatively poor LOD of 0.330 pg/mL. Our work revealed the vital importance of binding site of probes to DNA, and this principle can endow ratiometric biosensor with programmable analytical feature (e.g., linear range, LOD), allowing detections in various scenarios.

Incidence of Aflatoxin in Ready to Eat Nuts from Local Food Markets in Mangaluru, India

Abstract Background and Objective Aflatoxins are a group of naturally occurring mycotoxin which are toxic secondary metabolites produced by certain filamentous fungi like Aspergillus flavus and Aspergillus parasiticus. The main objective of this study was to screen the occurrence of aflatoxin in ready to eat nuts available locally and analyzing for its nutritive value and to evaluate the efficiency of conventional (thin-layer chromatography [TLC]) and sensitive kit-based (enzyme-linked immunosorbent assay [ELISA]) method by detection of the aflatoxin in the sample. Methods A total of 50 samples including peanuts (10), cashew nuts (10), almonds (10), pistachio (10), and walnuts (10) were collected from different stores in Mangalore city. Each sample was divided into three fractions, as for microbiological analysis, proximate analysis, and detection of aflatoxin by following standard method (AOAC2000). Results The present study evidenced the contamination of aflatoxin in all of the five types of ready-to-eat nuts examined and the concentration was within the acceptable limits. But, among the samples analyzed, G10 (groundnut) showed a maximum concentration of 16 µg/L aflatoxin detected by ELISA method. It was also observed that the proximate analysis mainly moisture content did not affect aflatoxin accumulation. Conclusion Our study shows that aflatoxin contamination of food products has become a serious threat. Although several methods for detection and quantification of toxins have been developed, due to their low concentration of toxicity in food commodities, an analytical method for detection and quantification of aflatoxin have to be specific, sensitive, and simple to carry out and among TLC and ELISA, ELISA came out as a suitable for rapid and sensitive detection.

Toxicogenic Fungi, Aflatoxins, and Antimicrobial Activities Associated with Some Spices and Herbs from Three Selected Markets in Ho Municipality, Ghana.

Spices and herbs are widely used food ingredients that enhance most organoleptic features of prepared foods. They are also used for medicinal and preservative purposes. Spices and herbs are potential carriers of bacteria, yeasts, and molds due to the nature of cultivation, harvest methods, storage conditions, packaging procedures, distribution, sale, and general handling. Although some fungi have been identified to be associated with most spices and herbs elsewhere in the world, little has been done on the presence of fungi in spices and herbs in Ghana. This study sought to identify the toxicogenic fungal profiles, mycotoxins (aflatoxins) present in some herbs, bay leaf (Laurus nobilis) and garden egg leaves (“gboma”) (Solanum macrocarpon), and spices, ginger (Zingiber officinale) and “dawadawa”(Parkia biglobosa), as well as to investigate the antimicrobial properties of the selected herbs and spices. The decimal reduction technique was used to plate onto Dichloran Rose Bengal Chloramphenicol (DRBC) agar media plates for fungal growth. Aflatoxin detection was carried out with high-performance liquid chromatographer connected to a fluorescence detector (HPLC-FLD). Antimicrobial properties were carried out using the agar diffusion method on solidified, freshly prepared Mueller-Hinton agar. A total of 12 species belonging to 7 genera, Aspergillus (niger, flavus, fumigatus, and ochraceus), Fusarium (oxysporum, verticillioides), Mucor (racemosus), Penicillium (digitatum, expansum), Rhizopus (stolonifer), Rhodotorula sp., and Trichoderma harzianum, were identified as fungal contaminants. Fusarium oxysporum was the most predominant species identified. Fresh ginger recorded the greatest number of colony-forming units (3.71 log10 CFU/g) with bay leaves recording the least number of colony counts (2.36 log10 CFU/g). Mycotoxin concentration detected in gboma was2.06 ± 0.07 μg/kgand in dawadawa was2.13 ± 0.09 μg/kg; however, mycotoxins were not detected in bay leaf and ginger. Ginger exhibited antibacterial activity against all bacteria ranging from 7.0 ± 0.0 mm to 12.0 ± 5.66 mm zones of inhibition. Ginger, bay leaf, and gboma extracts displayed fair antimicrobial activity against the bacteria investigated. On the other hand, dawadawa generally produced the least resistance against the five bacterial species but exhibited the highest zone of inhibition. All samples were slightly acidic with pH readings ranging from 5.81 to 6.76.

A novel method for non-invasive detection of aflatoxin contaminated dried figs with deep transfer learning approach

Aflatoxins are the most dangerous mycotoxin produced by Aspergillus fungal species, such as Aspergillus flavus and Aspergillus parasiticus, and can cause various health problems, including liver cancer, in humans. Figs and many agricultural products are affected by aflatoxins. It is crucial to detect it before consumption since it is impossible to clean aflatoxin from contaminated foods. Chromatographic methods are considered the gold standard for aflatoxin detection, but these methods are pretty expensive, time-consuming, and destructive. Therefore, various studies have been conducted on non-invasive aflatoxin detection using optical spectroscopic methods. Specifically, aflatoxin-contaminated figs are sorted manually by employees in production facilities using the Bright Greenish Yellow Fluorescence (BGYF) method under ultraviolet (UV) light. However, accurate and safe manual sorting depends on expertise of employees, along with this long exposure time to UV radiation may cause employees skin cancer and eye disorders. This study presents a deep transfer learning-based approach for non-invasive detection and classification of aflatoxin-contaminated dried figs using images captured under UV light. Pre-trained transfer learning models, such as DenseNet, ResNet, VGG, and InceptionNet, are applied to the dataset, but the accuracy of these models does not outperform the other methods that detect aflatoxin with the BGYF method. Therefore, fine-tuning is performed on the models. As a result, training accuracy of 98.57% and validation accuracy of 97.50% is obtained using the DenseNet169 model. The experimental results show that our proposed method achieves the highest accuracy among other methods. Also, the proposed method shows that deep CNN can be used to automatically, rapidly, and effectively detect aflatoxin-contaminated figs.

Detection of aflatoxin-producing fungi in maize

Maize samples (n = 110) were collected from five different areas of Dinajpur district from July 2018 to July 2019 for the detection of aflatoxin-producing fungi and aflatoxin. Aflatoxin-producing fungi were detected using culture and morphological features, and aflatoxin was detected using Agra Strip total aflatoxin test (20 ppb cut-off). Aspergillus spp. were detected in 56% of fresh and 23.2% of stored maize samples. Aflatoxin-producing fungi were detected in 28% of fresh samples and aflatoxin was detected in 10% of stored samples. Out of 110 maize samples, Aspergillus spp was identified in 38.2%, and aflatoxinproducing fungus was found in 18.2%. The presence of aflatoxin-producing fungus in stored maize increased significantly (P<0.01) with storage. In 20 samples aflatoxin level was more than 20 ppb. The Bangladesh Veterinarian (2020) 37(1 - 2): 27-35

Multispectral camera system design for replacement of hyperspectral cameras for detection of aflatoxin [formula omitted

The design of a multispectral camera system to replace hyperspectral cameras used in chemometrics laboratory for food research is a challenging task in the field of machine vision. In this paper, the process of designing and prototyping a low cost multispectral camera to measure aflatoxin B1 in almonds is described. A multispectral system with a Goldeye G-008 TEC1 SWIR is developed to replace a hyperspectral system with a Specim FX17 line scanner. Using R-squared and RMSE values of multiple linear regression, the performance of a hyperspectral camera system with a multispectral camera system were compared for measuring aflatoxin B1.The results show that a high speed multispectral system can replace an equivalent hyperspectral imaging system with much lower cost with an acceptable processing performance of 20 datacubes per seconds.

Dispersive micro solid phase extraction based ionic liquid functionalized ZnO nanoflowers couple with chromatographic methods for rapid determination of aflatoxins in wheat and peanut samples

Aflatoxins (AFs) contaminate agricultural products in a wide range of ways during their harvesting, storage and transport. Therefore, the detection of AFs has certain practical significance. Herein, a dispersive micro solid phase extraction (D-µSPE) technology was constructed based on 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF6]) fabricated ZnO nanoflowers for AFs extraction from food matrix before HPLC procedure. The key parameters affecting the extraction efficiency were studied. Under optimal experimental conditions, the method showed excellent linearity with high correlation coefficients (≥0.994). LOD and LOQ were 0.034 and 0.114 μg/kg for AFB1, 0.024 and 0.082 μg/kg for AFB2, 0.067 and 0.226 μg/kg for AFG1 and 0.025 and 0.084 μg/kg for AFG2. The recovery of actual samples spiked with analytes (at 5, 15 and 20 μg/kg) were from 93.8 to 105.1%. Overall, an accurate AFs analysis method was developed and could be applied to the determination of AFs in various food and agricultural products.

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.

Techniques used for Detection of Aflatoxins in Milk: A Review

Mycotoxins (aflatoxins) present in foods are serious health problems to consumers as they are highly toxic. The presence of high levels of AFM1 (aflatoxin) is an alarming issue in milk. So, the need of the hour is the development of a fast and reliable screening method for detecting trace aflatoxins in food. The analytical methods like HPLC and MS which have been used for aflatoxin detection are expensive, time-consuming and require many skills. Novel methods have been come up with high sensitivity, simplicity and capability of onsite monitoring which includes enzyme-linked immunosorbent assay (ELISA), immunosensors and lateral flow immunoassay (LFIA), etc. This paper reviews the techniques and methods used for the detection of aflatoxins in milk. Rapid technologies provide greater efficiency and sensitivity compared to conventional methods.

How do Time, Tannin, and Moisture Content Influence Toxicogenic Fungal Populations during the Storage of Sorghum Grains?

Cereal grains are usually ensiled to improve their nutritional value and are one of the main sources of feed for dairy cattle. However, during storage, grains can be contaminated with toxicogenic fungi. Sorghum is one of the most economically important cereals in the world. Therefore, the aim of this work was to evaluate the influence of storage duration and tannin and moisture content (MC) on toxicogenic fungal populations in sorghum grain storage. Samples that were prepared with varieties high in tannins (genotypes Morgan 108 and ACA 558, >5 g/kg dry matter) and with varieties low in tannin content (genotypes Flash 10 and ACA 546, <1 g/kg dry matter) were collected and manually compacted in experimental laboratory silos where they received different MC treatments: low (15 to 25%), medium (26 to 32%), and high (33 to 42%). Freshly harvested grains were analyzed at time 0, and stored grains were analyzed at 30, 90, and 180 days. Fungal isolation and identification were performed following conventional mycological methods. Penicillium citrinum (34%), Aspergillus flavus (60%), and Fusarium nygamai (68%) were the most abundant species. Rapid detection of aflatoxins and fumonisins in each sample was performed using enzyme-linked immunosorbent assay according to the AOAC method, and the quantification of aflatoxin B1 was performed using high-performance liquid chromatography. In four samples of pre- and poststorage grains, aflatoxins were detected with levels of 6.7 to 28.8 μg/kg and aflatoxin B1 with a level of 2 to 14 μg/kg. Fumonisins were only detected in two freshly harvested samples, with levels of 500 to 900 μg/kg. In general, storage time favored the increase of Penicillium populations and reduced Aspergillus and Fusarium. Conversely the abundance of the three populations was not affected by the MC. The results of this study show that fungal populations must be analyzed at different times.

Aflatoxin Total and Microbial Contamination of Grains, Oil Seeds, Yam Chips and Fish Sold in Maiduguri Market

Aflatoxins are secondary metabolites of fungus Aspergillus flavus and closely related species that infects severalagricultural commodities. The consumption of contaminated commodities adversely affects the health of humansand animals and also a cause of significant economic losses to producers. This study surveyed the aflatoxincontamination level of cowpea, maize, melon, groundnut, yam chips and fish sold in Maiduguri metropolis.Samples from each product (250 g) were bulked and thoroughly mixed using coning and quartering method to geta representative sample for analysis. Laboratory observations were carried out regarding microbial analysis,proximate composition and aflatoxin content. Samples for aflatoxin detection were classified into three; unsortedsamples, sorted samples and sorted/washed dried samples. Fish had the highest bacterial load 2.48 x 106 cfu/ml andAspergillus species were found to be the predominant fungi identified. Maize and groundnut with moisture contentof 5.63 and 5.62 had the highest total aflatoxin contamination (320.51 μg/kg and 236.3 μg/kg respectively) both inthe unsorted group. Total aflatoxin reduction of (58.82 - 99.99%) was observed in all the sorted samples andsorted/washed dried samples. It can be concluded that commonly sold food in Maiduguri had fungal and Aflatoxincontamination. Food should undergo several rounds of sorting to remove discoloured grains and grains that showsevidence(s) of deterioration to reduce the ingestion of food contaminated with aflatoxin.

AFLATOXIN M1 INDUCING GENOTOXICITY AND PATHOLOGICAL LESIONS IN ORGAN MEATS, LIVER OF CATTLE SAMPLED FROM EL-BASATIN ABATTOIR, EGYPT

In this study, two hundred and thirteen liver samples were randomly collected from different ages and both sexes of cattle carcasses in El-Basatin abattoir, Cairo governorate, Egypt. One hundred ninety- seven samples out of the examined specimens were free from any bacterial infections; but showed enlargement and pallor. Thirty-nine specimens representing about 20% of the bacteria- free specimens were examined to detect the Aflatoxins and its metabolites using thin layer chromatography (TLC) and LC MS/MS. All Pathological appraisals were recorded and the genotoxicity of the studied mycotoxin was detected using single cell gel electrophoresis (Comet). Our study revealed that there were prominent deleterious effects of Aflatoxin M1 on the hepatic tissue. The detection of aflatoxins’ metabolites in the hepatic tissues is of great importance on the health of human consuming organ meat; and on the other hand, it may affect the farm animals’ performance.

Design, Elaboration, and Characterization of an Immunosensor for the Detection of a Fungal Toxin in Foodstuff Analyses

This work describes the complete elaboration of an immunosensor for the detection of the fungal B1 aflatoxin (AFB1). In a first step, a system made of three screen-printed electrodes (SPEs) was manufactured using gold, silver/silver chloride, and carbon pastes. Raman spectroscopy showed that the thermal treatment applied to the electrodes enabled a strong decrease in the amount of undesirable organic molecules for each paste. Atomic Force Microscopy was also used to reveal the morphology of the electrode surfaces. In a second step, an autonomous and cheap electronic system was designed for the control of the sensor and electrochemical measurements, showing current variations significantly higher than those observed with a commercial system. In a last step, the gold working electrode of this system was functionalized by a simple self-assembly method, optimized in a previous work, with a molecular architecture including an antibody recognizing specifically AFB1. The complete device was finally realized by combining the SPEs and the electronic platform. The resulting setup was able to detect AFB1 toxin in a buffer with an LOD of about 50 fg/mL. It was then applied to the detection of AFB1 in rice milk, a more realistic medium comparable with those met in an agrifood context. The electrochemical detection of AFB1 was possible in a range of concentration between 0.5 pg/mL and 2.5 pg/mL, with the sensor behaving linearly in this range.

3D structured biochip for label free determinations at the point-of-need

A novel optical label-free biosensing approach is introduced aiming to remove the current limitations of optical biosensors in their application of on-site food analysis. The proposed methodology (GRADual thin film IntErferometry, GRADE) is based on light interferometry employing an illumination source of a few nm spectral width and a 3D micro-patterned sensor surface consisting of multilevel staircase structures, fabricated through grayscale electron beam lithography and appropriate pattern transfer on thick dielectric layer. The formation of the biomolecular adlayer on the 3D structured surface sensor, is monitored with a 2D camera, without the need for broadband illumination sources and spectral analysis instrumentation. Consequently, this novel sensing approach has the potential to enable the cost-efficient monitoring of bioreactions employing a simple optical setup, a low-cost photodetector and light source, thus being an ideal platform for use at the Point-of-Need. In the present study the system is demonstrated for the detection of aflatoxin B 1 (AFB1), a very potent carcinogen detected in various food categories. • A novel optical label-free biosensing approach is introduced aiming to remove the current limitations of optical biosensors. • Based on a sensing area with a gradually-varying-thickness dielectric, fabricated through grayscale e-beam lithography. • Cost-efficient monitoring of bioreactions, ideal platform for use at the Point-of-Need.