Aflatoxins In Peanuts Research Articles

Identification of aflatoxin B1 in peanut using near-infrared spectroscopy combined with naive Bayes classifier

Peanuts are easily contaminated by a variety of mycotoxins during growth, transportation, and storage, of which aflatoxin B1 is the most common. Aflatoxin B1 is one of the most toxic carcinogens known, and it can cause liver damage to varying degrees after ingestion. To explore the feasibility of detecting aflatoxin B1 contamination in peanuts by near-infrared spectroscopy, 115 peanut samples with aflatoxin B1 content in the range of 2.44 to 223.76 μg/kg were prepared. The near-infrared spectroscopy data of the peanut sample in the 940–1660 nm band was obtained, and the naive Bayes qualitative discrimination model based on the whole band was established. To improve accuracy and reduce dimensions, simplified models were built using characteristic wavelengths screened by Successive Projection Algorithm and Elimination of Uninformative Variables. The built model is verified internally and externally by omitting cross-validation. In comparison, the second derivative Savitzky–Golay Elimination of Uninformative Variables normal kernel density estimation naive Bayes model reached the optimum discriminant accuracy, with the comprehensive overall accuracy of validation set and prediction set were over 91.00%, areas under receiver operating characteristic curves was over 0.90. The results showed that the accuracy of the quantitative determination of aflatoxin B1 in peanuts by near-infrared spectroscopy was high, with a boundary of 20 μg/kg. This method is suitable for the qualitative determination of peanut aflatoxin B1.

A Review of the Research Status of Aflatoxin in Peanuts

Food safety is an important part of the healthy safety system and is closely related to people’s health. Peanut is an important daily food and oil product in China. It is very important to ensure its safety, but peanuts are easily contaminated by aflatoxin. How to efficiently detect aflatoxin in peanut is particularly important. This paper reviews the related research literature of aflatoxin in peanuts at home and abroad in recent years, discusses its sources, hazards and detection methods. The advantages of laser-induced fluorescence detection technology were discussed, and some suggestions for the future detection of aflatoxin in peanut were put forward.

Spatial analysis of dietary exposure of aflatoxins in peanuts and peanut oil in different areas of China

Peanuts in China are heavily contaminated with aflatoxin, which pose a threaten to human health. To compare the dietary exposure risk of aflatoxins (AFT) in peanuts and peanut oil in different areas of China, the spatial distribution of AFT contamination levels in peanuts and peanut oil from different areas was analyzed. The dietary exposure was calculated by simple distributed risk assessment method before characterizing the health risk using both the margin of exposure (MOE) approach proposed by the European Food Safety Authority (EFSA) and the quantitative liver cancer risk approach proposed by the Joint Food and Agricultural Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives (JECFA). The results showed that the AFT content in peanuts and peanut oil was high with agglomeration in several provinces of East and South China under a subtropical temperate monsoon climate, and the AFT contamination in peanut oil was more substantial than peanuts. On average, the estimated dietary exposure to AFT from the total of peanuts and peanut oil for Chinese general population ranged from 1.776 to 1.940 ng/kg bw/day (LB-UB), from which the MOE values of 88–96 (UB-LB) and liver cancer risk of 0.055–0.060 cases/100,000 persons/year (LB-UB) were calculated. As for different areas in China, the mean AFT exposure ranged between 0.000 and 17.270 ng/kg bw/day. Moreover, the corresponding health risk was estimated at 10–868759 MOE values and 0.000–0.851 liver cancer cases/100,000 persons/year. Guangdong, Fujian and Jiangxi provinces were at a higher risk rank. The liver cancer risk of AFT exposure from peanuts and peanut oil was far below all-cause liver cancer incidence (18.0 cases/100,000 persons/year) in China, but several areas with relatively high risk should be of concern. Compared with other age groups, children aged 2–6 years should be paid more attention because they have the highest AFT exposure level.

Development of Anti-Idiotypic Nanobody-Phage Based Immuno-Loop-Mediated Isothermal Amplification Assay for Aflatoxins in Peanuts.

Aflatoxin contamination in agricultural products has posed serious health hazards and brought huge economic loss in the food and feed industries. Monitoring aflatoxins in various foods and feeds has become a crucial means to protect public health. This study aimed to report an immuno-loop-mediated isothermal amplification (iLAMP) assay by using an anti-idiotypic nanobody-phage for on-site and rapid detection of aflatoxin in real samples. The iLAMP method was developed on the basis of a competitive immunoassay and LAMP reaction performed in a simple water bath. This method can provide visualized test results: violet color represents positive samples while sky blue represents negative. The visual detection limits of iLAMP for aflatoxin B1, B2, G1, and G2 in peanut samples were 1.6, 1.6, 3.2, and 16 μg/kg, respectively. The developed assay was verified with high performance liquid chromatography (HPLC) for the analysis of aflatoxins in peanuts, which demonstrated that the iLAMP method can be applied to the detection of aflatoxin in real samples. The novel iLAMP assay eliminates the need for aflatoxin conjugates, the antibody labeling process, and special equipment, and offers an alternative to existing methods with advantages of time-saving, cost-effectiveness, and ease-of-use.

Analysis of small RNA populations generated in peanut leaves after exogenous application of dsRNA and dsDNA targeting aflatoxin synthesis genes

Previously, we have shown that RNA interference (RNAi) can prevent aflatoxin accumulation in transformed peanuts. To explore aflatoxin control by exogenous delivery of double-strand RNA (dsRNA) it is necessary to understand the generation of small RNA (sRNA) populations. We sequenced 12 duplicate sRNA libraries of in-vitro-grown peanut plants, 24 and 48 h after exogenous application of five gene fragments (RNAi-5x) related to aflatoxin biosynthesis in Aspergillus flavus. RNAi-5x was applied either as double-stranded RNA (dsRNA) or RNAi plasmid DNA (dsDNA). Small interfering RNAs (siRNAs) derived from RNAi-5x were significantly more abundant at 48 h than at 24 h, and the majority mapped to the fragment of aflatoxin efflux-pump gene. RNAi-5x-specific siRNAs were significantly, three to fivefold, more abundant in dsDNA than dsRNA treatments. Further examination of known micro RNAs related to disease-resistance, showed significant down-regulation of miR399 and up-regulation of miR482 in leaves treated with dsDNA compared to the control. These results show that sRNA sequencing is useful to compare exogenous RNAi delivery methods on peanut plants, and to analyze the efficacy of molecular constructs to generate siRNAs against specific gene targets. This work lays the foundation for non-transgenic delivery of RNAi in controlling aflatoxins in peanut.

The climate-induced alteration of future geographic distribution of aflatoxin in peanut crops and its adaptation options

Because of its negative effect on health, aflatoxin has become one of the most important mycotoxins in the world. As climate stress is one of the main triggers of aflatoxin incidence, climate change could affect its geographic distribution. The primary aim of this study was to examine the effect of climate change on the future distribution of aflatoxin in peanut (Arachis hypogaea L.) crops in Australia. The projected distributions in 2030, 2050, 2070, and 2100 were modelled by employing the CLIMEX (CLIMatic indEX) model using two global climate models (GCMs), i.e. CSIRO-Mk3.0 and MIROC-H based on SRES A2 and SRES A1B climate scenarios. This study has successfully developed CLIMEX model parameters for aflatoxin and confirmed the climatic zone preference of aflatoxin incidence, as concluded by other studies. Therefore, the model parameters are applicable in all parts of the world. The projection results in Australia confirm that climate change affects the future distribution of aflatoxin, including the distribution in the current peanut-growing areas. Shifts in aflatoxin invasion areas from the tropical and subtropical climate zones of the eastern part of Australia to the temperate climate zones of the south-eastern and south-western parts of the country were projected by 2100. Thus, adaptation and mitigation measures are needed to overcome the negative impacts in the future. Options for these measures include relocation of planting areas, development of host-plant resistance, proper agricultural practices, and mitigation actions by using physical, chemical, and biological approaches.

Moisture and Aflatoxin Contents of Kenyan Market Peanuts and Decontamination with Water, Lime and Ultraviolet Radiation Treatments

In the recent past, aflatoxin in peanuts and products has been a subject of controversy in Kenya. In the early 2019, some brands of locally manufactured peanut butter were withdrawn from the market shelves on account of containing aflatoxin higher than the national tolerance. It has been established that Kenyan market peanuts contain high levels of aflatoxin. Roasting is reported to have little effect on the aflatoxin content. This study was designed to assess the effect of specific treatments prior to roasting in reducing the aflatoxin levels to below the tolerance. This would then ensure compliance of the toxin levels in the roasted peanuts and the products with the national tolerance. The treatments included soaking in water, in lime, and UV irradiation. The peanut samples were collected from 20 vendors in the Main Cereal Market in Nairobi and brought to the laboratory of the Kenya Bureau of Standards (KEBS). They were analysed for moisture and aflatoxin content. Each sample was subjected to the treatment and reduction was evaluated in aflatoxin to the tolerance. The moisture content of the peanuts varied from 5.2 – 8.4% with mean of 6.5%. Moisture almost complied with the optimum for storage of 8.0%. The total aflatoxin contents varied from 3.3 – 38.5 ppb with mean of 14.8 ppb. Up to 45% samples had aflatoxin above tolerance of 10 ppb.
 There was positive and significant (p < 0.01) correlation between aflatoxin levels and moisture content. Treatment of the peanuts with water (cold & warm) and warm lime and irradiation with UV all managed to reduce the aflatoxin contents to below the tolerance, in the order lime>warm water>cold water>UV irradiation. The study concluded that the moisture content of the market peanuts in Kenya, almost complies with recommended optimum for storage the tolerance, but the mean aflatoxin content was well above the tolerance. However, the aflatoxin levels can be lowered effectively by soaking in water, lime, and by irradiation with UV.

Thermosensitive Hydrogel for Encapsulation and Controlled Release of Biocontrol Agents to Prevent Peanut Aflatoxin Contamination.

Starch, alginate, and poly(N-isopropylacrylamide) (PNIPAAm) were combined to prepare a semi-interpenetrating network (IPN) hydrogel with temperature sensitivity. Calcium chloride was used as cross-linking agent, the non-toxigenic Aspergillus flavus spores were successfully encapsulated as biocontrol agents by the method of ionic gelation. Characterization of the hydrogel was performed by Fourier-transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), and thermogravimetry analysis (TGA). Formulation characteristics, such as entrapment efficiency, beads size, swelling behavior, and rheological properties were evaluated. The optical and rheological measurements indicated that the lower critical solution temperature (LCST) of the samples was about 29–30 °C. TGA results demonstrated that the addition of kaolin could improve the thermal stability of the semi-IPN hydrogel. Morphological analysis showed a porous honeycomb structure on the surface of the beads. According to the release properties of the beads, the semi-IPN hydrogel beads containing kaolin not only have the effect of slow release before peanut flowering, but they also can rapidly release biocontrol agents after flowering begins. The early flowering stage of the peanut is the critical moment to apply biocontrol agents. Temperature-sensitive hydrogel beads containing kaolin could be considered as carriers of biocontrol agents for the control of aflatoxin in peanuts.

Effects of atmospheric pressure plasma jet treatment on aflatoxin level, physiochemical quality, and sensory attributes of peanuts

Atmospheric pressure plasma jet (APPJ) was investigated as an alternative to chemical and thermal treatments for reducing aflatoxin (AFT) levels on peanuts. Kernels were inoculated with Aspergillus flavus to produce AFTs. They were then treated using two APPJ treatment regimens; constant exposure (for 1 and 2 min), and pneumatically agitated exposure in a conveyored channel for up to 5 min. Quality was assessed via, peroxide value, free fatty acid content, acidity value, oxidative stability index, and through sensory panel evaluation. After 2 min of constant APPJ treatment, AFTs were reduced from 62.3 to 48.2 ppb (23% reduction), with a corresponding change in temperature (ΔT −24 to 92°C) of treated sample. After 5 min of agitated treatment, AFT concentration was reduced from 64.14 to 39.6 ppb (38% reduction) with a ΔT (24–78°C) of treated sample. APPJ compares favorably to other AFTs reduction techniques in time and product quality. Few changes were observed in all quality indices, this suggests APPJ is a viable approach for peanut aflatoxin treatment. Practical applications This work demonstrates reduction of aflatoxin on peanuts using APPJ technology. Sensory evaluation scored plasma-treated peanuts well, relative to untreated controls. Atmospheric pressure plasma treatment represents a promising method for reducing aflatoxin levels in peanuts.

Pixel-level aflatoxin detecting based on deep learning and hyperspectral imaging

Aflatoxin is a kind of virulent and strong carcinogenic substance, and it is found widely in peanut, Maize and their agricultural products. In order to detect Aflatoxin in peanut, we first built a hyperspectral imaging system using a grating module, SCOMS camera, and electric displacement platform, and acquired 146 hyperspectral images cubes of 73 peanut samples before and after contaminated with aflatoxin. Then, we proposed a reshaped image method of pixel spectral for the CNN method. By studying on random selection data-sets and comparing with different identification models, we found that: (1) Reshape image established by the pixel level spectral is good enough for aflatoxin detected problems, overall recognition rate reached above 95% on pixel-level. (2) The deep learning method is worked well and it is better than traditional identification models, not only on the pixel level but also on the kernel identification. The recognition rate of above 90% on the kernel level can quickly use in sorting machine's design.

Antifungal activity of volatile emitted from Enterobacter asburiae Vt-7 against Aspergillus flavus and aflatoxins in peanuts during storage

The contamination of food with Aspergillus flavus and subsequent aflatoxins is considered as one of the most severe safety problems in the world. The application of microorganisms and the produced bio-active compounds is considered as the most promising method for controlling foodborne pathogens and mycotoxins contamination both in pre- and post-harvest. Vt-7, identified as Enterobacter asburiae, was able to completely inhibit the growth of Aspergillus flavus (AF) and other seven important fungal pathogens by the production of volatiles. Additionally, it can also significantly inhibited AF infection on peanuts in storage, down-regulated the gene expression of aflatoxin biosynthesis and eventually prevented aflatoxins production. Scanning electron microscope further proved that Vt-7 volatiles prevented conidia germination of AF on peanut surface, and severely destroyed the conidia structure. Gas chromatography – tandem mass spectrometry revealed that two abundant compounds (1-Pentanol and Phenylethyl Alcohol) were involved in the volatile profiles. They showed great antagonistic activity against AF with minimal inhibitory concentration at 200 μL/L. Therefore, E. asburiae Vt-7, and volatiles 1-Pentanol and Phenylethyl Alcohol were effective agents in controlling AF and aflatoxins in peanut during storage. They will provide novel strategies for the application of microbe and bio-active compounds against fungal pathogens and mycotoxins in food and grains during storage.

Identification of genomic regions and diagnostic markers for resistance to aflatoxin contamination in peanut (Arachis hypogaea L.)

BackgroundAflatoxin contamination caused by Aspergillus flavus is a major constraint to peanut industry worldwide due to its toxicological effects to human and animals. Developing peanut varieties with resistance to seed infection and/or aflatoxin accumulation is the most effective and economic strategy for reducing aflatoxin risk in food chain. Breeding for resistance to aflatoxin in peanut is a challenging task for breeders because the genetic basis is still poorly understood. To identify the quantitative trait loci (QTLs) for resistance to aflatoxin contamination in peanut, a recombinant inbred line (RIL) population was developed from crossing Zhonghua 10 (susceptible) with ICG 12625 (resistant). The percent seed infection index (PSII), the contents of aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) of RILs were evaluated by a laboratory kernel inoculation assay.ResultsTwo QTLs were identified for PSII including one major QTL with 11.32–13.00% phenotypic variance explained (PVE). A total of 12 QTLs for aflatoxin accumulation were detected by unconditional analysis, and four of them (qAFB1A07 and qAFB1B06.1 for AFB1, qAFB2A07 and qAFB2B06 for AFB2) exhibited major and stable effects across multiple environments with 9.32–21.02% PVE. Furthermore, not only qAFB1A07 and qAFB2A07 were co-localized in the same genetic interval on LG A07, but qAFB1B06.1 was also co-localized with qAFB2B06 on LG B06. Conditional QTL mapping also confirmed that there was a strong interaction between resistance to AFB1 and AFB2 accumulation. Genotyping of RILs revealed that qAFB1A07 and qAFB1B06.1 interacted additively to improve the resistance to both AFB1 and AFB2 accumulation. Additionally, validation of the two markers was performed in diversified germplasm collection and four accessions with resistance to aflatoxin accumulation were identified.ConclusionsSingle major QTL for resistance to PSII and two important co-localized intervals associated with major QTLs for resistance to AFB1 and AFB2. Combination of these intervals could improve the resistance to aflatoxin accumulation in peanut. SSR markers linked to these intervals were identified and validated. The identified QTLs and associated markers exhibit potential to be applied in improvement of resistance to aflatoxin contamination.

Assessing Aflatoxin Exposure Risk from Peanuts and Peanut Products Imported to Taiwan

Aflatoxins are highly toxic and cause disease in livestock and humans. In order to assess Taiwan population exposure to aflatoxin from peanuts and peanut products, a total of 1089 samples of peanut candy, peanut butter, and peanuts etc. were collected in the period from 2011 to 2017 and analyzed using a liquid chromatography/tandem mass spectrometer. The overall mean contamination levels of aflatoxin in peanuts and peanut products were 2.40 μg/kg of aflatoxin B1, 0.41 μg/kg of aflatoxin B2, 0.19 μg/kg of aflatoxin G1, and 0.03 μg/kg of aflatoxin G2. We use margin of exposure (MOE) as a tool to improve food safety management. According to MOE levels of aflatoxins in peanuts and peanut products from China, Indonesia, Thailand, the United States, and the Philippines were above the safe lower limit of 10,000, indicating an absence of public health or safety risk for the majority of the population. However, products from Vietnam were under the MOE safe lower limit, suggesting that regulatory actions must be continued to avoid excessive consumer exposure.

Identification of Sources of Resistance for Peanut Aspergillus flavus Colonization and Aflatoxin Contamination

Peanut aflatoxin contamination caused by Aspergillus flavus is a serious constraint for food safety and human health in Senegal. The present study aimed to identify sources of resistance for A. flavus colonization and aflatoxin contamination. Thus, seeds from 67 peanut genotypes were tested under laboratory conditions. Aqueous conidial suspension of an aflatoxinogenic strain of A. flavus was used for inoculation in Petri dishes containing ten seeds of each genotype, and data on incidence and severity were recorded. Total aflatoxin concentration in seeds was determined on 15th day after inoculation using mReader® method. Results showed a significant (p<0.001) variation of aflatoxin, incidence and severity among the tested peanut genotypes. Incidence ranged from 0 to 70% with a mean of 20.36 ± 0.8%. Out of the 67 genotypes, eight showed incidence less than 10%. Severity ranged from 0 to 44% with a mean value of 8.82 ± 0.45%. The genotype 12CS_104 showed aflatoxin concentration level in conformity with the European standard (4 ppb). Out of three clusters revealed by hierarchical classification based on disease incidence and severity, the cluster 1 contained 33 genotypes characterised by low incidence and severity values. These genotypes can be tested under field conditions to confirm their resistance to A flavus.

Assessing pulsed light treatment on the reduction of aflatoxins in peanuts with and without skin

SummaryAflatoxin(s) (AFTs) are secondary metabolites of some Aspergillus molds commonly found in peanuts. This study aimed to reduce AFTs (B1 and B2) on contaminated peanuts (with and without skin) using Pulsed Light (PL) treatment for 1, 2, 3, 4 and 5 min at 5 cm distance from the light strobe. After PL treatment, AFT levels were determined using ELISA and LC‐MS‐MS. Quality parameters of treated peanuts and oil were evaluated by comparing to control samples. Results of with‐skin and without‐skin peanuts showed 82% and 91% AFTs reduction, respectively. No significant differences (P > 0.05) were observed for all peanut oil quality parameters while the differences in peanut kernel colour under these conditions were significant (P < 0.05) in comparison with control samples. At the industrial level, PL may offer an effective AFTs reduction in peanuts. However, PL treatment parameters should be optimised to achieve better appearance.

Occurrence and exposure assessment to aflatoxins in peanuts commercialized in the northwest of Parana, Brazil

ABSTRACT: Peanuts are a nutritious food consumed worldwide. Some species of the genus Aspergillus, producers of aflatoxins, colonize peanuts. Human exposure to aflatoxins occurs by ingesting contaminated foods. The objective of this paper was to assess the occurrence and dietary exposure of the population to aflatoxins in peanuts commercially available in Maringa, Brazil, from May 2013 to April 2017. A total of 104 peanut samples were evaluated by thin-layer chromatography and confirmed by derivatization with trifluoroacetic acid. The contamination rate detected was 24.0% in average concentration of 13.4µg/kg. Twenty positive samples (19.2%) exceeded the maximum level permitted in Brazil for the sum of four aflatoxins. Estimated probable daily intake was 1,28 µg/kg body weight/day, exceeding the Provisional Maximum Tolerable Daily Intake (0.001μg/kg body weight/day). According to the high levels of aflatoxins found in peanuts, there is need for further monitoring the presence of aflatoxins in peanuts in natura to reduce the levels of contamination.

Probabilistic health risk assessment for dietary exposure to aflatoxin in peanut and peanut products in Taiwan

Aflatoxins are secondary metabolites naturally occurring in many foods such as peanuts, spices, rice, tree nuts, and maize. Aflatoxins are both genotoxic and carcinogenic substances and can cause severe adverse health effects. The purpose of this study is to estimate the probabilistic risk of consuming aflatoxin-contaminated peanuts and peanut products. Concentration data (1.84 ± 4.03 ppb) were gathered from the Taiwan Food and Drug Administration (TFDA) between 2005 and 2015, along with consumption rate data (from Nutrition and Health Survey in Taiwan) for five age groups, namely 1-2 years (babies), 3-9 years (toddlers), 10-17 years (teenagers), 18-65 years (adults), and above 65 (elderly), in two sub-populations (whole group and consumer only). These data are essential material for exposure analysis. According to the benchmark dose lower confidence limit 10% (BMDL10) (170 ng/kg bw/day) suggested by the European Food Safety Authority (EFSA), the calculated margin of exposure (MOE) value cannot reach 10,000. Cancer potency data from Joint FAO/WHO Expert Committee on Food Additives (JECFA) indicates that the estimated population risk ranges from 0.0007 to 0.2713 cancers/100,000 population/year. Although aflatoxin contamination does not seem to largely account for the occurrence of liver cancer in Taiwan, MOE calculations point out that it may cause potential health concerns.

Occurrence of Aflatoxigenic <i>Aspergillus</i> Species in Peanut Varieties in Busia and Kisii Central Districts, Kenya

Recent studies have shown that peanuts in Kenya are highly contaminated with aflatoxins, however, information gaps exist on the characterization of the Aspergillus species that produce aflatoxins. Therefore, this gap necessitated the determination of the Aspergillus species producing aflatoxins in peanuts from the main growing districts of Busia and Kisii central. One hundred and two (102) peanuts samples were collected from farmers’ in each district and Aspergillus species were isolated using the dilution plate technique on modified Rose Bengal Agar. Phenotypical characterization of the identified Aspergillus flavus isolates from the samples was determined using the procedure of Mellon and Cotty. This study identified 5 Aspergillus species as contaminants in peanut analyzed. They were Aspergillus flavus L-strain, Aspergillus flavus S-strain, Aspergillus parasiticus, Aspergillus niger and Aspergillus tamari. Overall, the occurrence of Aspergillus flavus L-strain and A. flavus S-strain was significantly higher than other species identified (H = 15.55, df = 4, P = 0.004) in peanuts from the two districts. Aspergillus flavus L-strain was the most common isolate (58.8%) in peanut from Busia district while A. flavus S-strain was the most common strain (60.2%) in peanuts from Kisii central district. However, A. flavus S-strain was the most dominant species (F = 3.15, df = 25, P = 0.031) with an overall mean occurrence of 45.1%. The confirmation of occurrence of other species that produce toxins such as A. niger and A. tamarii which also produces cyclopiazonic acid, points to the need of screening peanuts for other carcinogenic mycotoxins.

High-sensitivity direct analysis of aflatoxins in peanuts and cereal matrices by ultra-performance liquid chromatography with fluorescence detection involving a large volume flow cell

ABSTRACTThis paper reports a sensitive and cost effective method of analysis for aflatoxins B1, B2, G1 and G2. The sample preparation method was primarily optimised in peanuts, followed by its validation in a range of peanut-processed products and cereal (rice, corn, millets) matrices. Peanut slurry [12.5 g peanut + 12.5 mL water] was extracted with methanol: water (8:2, 100 mL), cleaned through an immunoaffinity column and thereafter measured directly by ultra-performance liquid chromatography-fluorescence (UPLC-FLD) detection, within a chromatographic runtime of 5 minutes. The use of a large volume flow cell in the FLD nullified the requirement of any post-column derivatisation and provided the lowest ever reported limits of quantification of 0.025 for B1 and G1 and 0.01 μg/kg for B2 and G2. The single laboratory validation of the method provided acceptable selectivity, linearity, recovery and precision for reliable quantifications in all the test matrices as well as demonstrated compliance with the EC 401/2006 guidelines for analytical quality control of aflatoxins in foodstuffs.

An On-Site, Ultra-Sensitive, Quantitative Sensing Method for the Determination of Total Aflatoxin in Peanut and Rice Based on Quantum Dot Nanobeads Strip.

An on-site, ultra-sensitive, and quantitative sensing method was developed based on quantum dot nanobeads (QDNBs) and a test strip for the determination of total aflatoxins (AFTs) in rice and peanuts. The monoclonal antibody against AFT (mAbAFT) was homemade and labeled with QDNB. After the pre-coating of the AFT antigen on the test line (T line), the competitive immunoreactions were conducted between AFT and AFT antigen on the T line with QDNBs-mAbAFT. Under optimal conditions, this approach allowed a rapid response towards AFT with a considerable sensitivity of 1.4 pg/mL and 2.9 pg/mL in rice and peanut matrices, respectively. The put-in and put-out durations were within 10 min. The recoveries for AFT in rice and peanut sample matrices were recorded from 86.25% to 118.0%, with relative deviations (RSD) below 12%. The assay was further validated via the comparison between this QDNB strip and the conventional HPLC method using spiked samples. Thus, the design provided a potential alternative for on-site, ultra-sensitive, and quantitative sensing of AFT that could also be expanded to other chemical contaminants for food safety.