Near-infrared hyperspectral imaging for detecting Aflatoxin B1 of maize kernels

The feasibility of detecting the Aflatoxin B₁ in maize kernels inoculated with Aspergillus flavus conidia in the field was assessed using near-infrared hyperspectral imaging technique. After pixel-level calibration, wavelength dependent offset, the masking method was adopted to reduce the noise and extract region of interest (ROI's) of spectral image, then an explanatory principal component analysis (PCA) followed by inverse PCA and secondary PCA was conducted to enhance the signal to noise ratio (SNR), reduce the dimensionality, and extract valuable information of spectral data. By interactive analysis between score image, score plot and load line plot, the first two PCs were found to indicate the spectral characteristics of healthy and infected maize kernels respectively. And the wavelengths of 1729 and 2344 nm were also identified to indicate AFB₁ exclusively. The n-dimensional visualization method based on PC₃ to PC₇ was adapted to select the two classes of end members as the input data of the spectral angle mapper (SAM) classifier to separate the aflatoxin infection and clean kernels. The result was compared with chemical analysis of Aflatest^®. And the verification accuracy of pixel level reached 100% except the tip parts of some healthy kernels were falsely identified as aflatoxin contamination. Furthermore, another 26 maize kernels were selected as an independent data set to verify the reproducibility of the method proposed, and the detection accuracy attained to 92.3%, which demonstrated that hyperspectral imaging technique can be used to detect aflatoxin in artificially inoculated maize kernels in the field.     

Identification of aflatoxin B1 on maize kernel surfaces using hyperspectral imaging

A shortwave infrared (SWIR) hyperspectral imaging system with wavelength range between 1000 and 2500 nm was used to assess the potential to detect aflatoxin B₁ (AFB₁) contaminants on the surface of healthy maize kernels. Four different AFB₁ solutions were prepared and deposited on kernels surface to achieve 10, 20, 100, and 500 ppb, respectively. A drop of 20% methanol was dipped on the surface of 30 healthy kernels in the same way to generate the control samples. Based on the standard normal variate (SNV) transformation spectra, principal components analysis (PCA) was used to reduce the dimensionality of the spectral data, and then stepwise factorial discriminant analysis (FDA) was performed on latent variables provided by the PCA's. Furthermore, beta coefficients of the first three of four discriminant factors were analyzed and key wavelengths, which can represent AFB₁ and be used to differentiate different level of AFB₁ were indentified. Furthermore, 150 independent samples were used as verification set to test the reproducibility of the proposed method. A minimum classification accuracy of 88% was achieved for the validation set and verification set. Results indicated that hyperspectral imaging technology, accompanied by the PCA-FDA method, can be used to detect AFB₁ at concentrations as low as 10 ppb when applied directly on the maize surface.     

Multi-spectral kernel sorting to reduce aflatoxins and fumonisins in Kenyan maize

Maize, a staple food in many African countries including Kenya, is often contaminated by toxic and carcinogenic fungal secondary metabolites such as aflatoxins and fumonisins. This study evaluated the potential use of a low-cost, multi-spectral sorter in identification and removal of aflatoxin- and fumonisin-contaminated single kernels from a bulk of mature maize kernels. The machine was calibrated by building a mathematical model relating reflectance at nine distinct wavelengths (470–1550 nm) to mycotoxin levels of single kernels collected from small-scale maize traders in open-air markets and from inoculated maize field trials in Eastern Kenya. Due to the expected skewed distribution of mycotoxin contamination, visual assessment of putative risk factors such as discoloration, moldiness, breakage, and fluorescence under ultra-violet light (365 nm), was used to enrich for mycotoxin-positive kernels used for calibration. Discriminant analysis calibration using both infrared and visible spectra achieved 77% sensitivity and 83% specificity to identify kernels with aflatoxin >10 ng g⁻¹ and fumonisin >1000 ng g⁻¹, respectively (measured by ELISA or UHPLC). In subsequent sorting of 46 market maize samples previously tested for mycotoxins, 0–25% of sample mass was rejected from samples that previously tested toxin-positive and 0–1% was rejected for previously toxin-negative samples. In most cases where mycotoxins were detected in sorted maize streams, accepted maize had lower mycotoxin levels than the rejected maize (21/25 accepted maize streams had lower aflatoxin than rejected streams, 25/27 accepted maize streams had lower fumonisin than rejected streams). Reduction was statistically significant (p < 0.001), achieving an 83% mean reduction in each toxin. With further development, this technology could be used to sort maize at local hammer mills to reduce human mycotoxin exposure in Kenya, and elsewhere in the world, while at once reducing food loss, and improving food safety and nutritional status.     

Non-destructive detection of blackspot in potatoes by Vis-NIR and SWIR hyperspectral imaging

Blackspot is a subsurface potato damage resulting from impacts during harvesting. This type of bruising represents substantial economic losses every year. As the tubers do not show external symptoms, bruise detection in potatoes is not straightforward. Therefore, a nondestructive and accurate method capable of identifying bruised tubers is needed. Hyperspectral imaging (HSI) has been shown to be able to detect other subsurface defects such as bruises in apples. This method is nondestructive, fast and can be fully automated. Therefore, its potential for non-destructive detection of blackspot in potatoes has been investigated in this study. Two HSI setups were used, one ranging from 400 to 1000 nm, named Visible-Near Infrared (Vis-NIR) and another covering the 1000–2500 nm range, called Short Wave Infrared (SWIR). 188 samples belonging to 3 different varieties were divided in two groups. Bruises were manually induced and samples were analyzed 1, 5, 9 and 24 h after bruising. PCA, SIMCA and PLS-DA were used to build classifiers. The PLS-DA model performed better than SIMCA, achieving an overall correct classification rate above 94% for both hyperspectral setups. Furthermore, more accurate results were obtained with the SWIR setup at the tuber level (98.56 vs. 95.46% CC), allowing the identification of early bruises within 5 h after bruising. Moreover, the pixel based PLS- DA model achieved better results in the SWIR setup in terms of correctly classified samples (93.71 vs. 90.82% CC) suggesting that it is possible to detect blackspot areas in each potato tuber with high accuracy.     

Aflatoxin B1 degradation by Bacillus subtilis UTBSP1 isolated from pistachio nuts of Iran

Pistachio nuts are among the commodities with the highest risk of aflatoxin contamination in Iran. Aflatoxin B1 (AFB1) is one of the most hazardous mycotoxins for humans and livestock. In nature, there are microorganisms which are capable of reducing aflatoxins contamination in food and feed products. In this study, Bacillus subtilis strain UTBSP1 was isolated from pistachio nuts and studied for the degradation of AFB1. The AFB1 contents were determined by the use of HPTLC and HPLC as well as multiple reactions monitoring (MRM) method in LC-MS/MS. The results indicated B. subtilis UTBSP1 could considerably remediate AFB1 from nutrient broth culture and pistachio nut by 85.66% and 95%, respectively. Cell free supernatant fluid caused an apparent 78.39% decrease in AFB1 content. The optimal conditions for AFB1 degradation by cell free supernatant appeared at 35-40 °C, during 24 h. Furthermore, the results indicated that AFB1 degradation is enzymatic and responsible enzymes are extracellular and constitutively produced. The destructive AFB1 differed from standard AFB1 chemically, and lost a fluorescence property.     

An initial characterization of aflatoxin B1 contamination of maize sold in the principal retail markets of Kigali,Rwanda

Food security considerations have shifted in recent years, with the recognition that available food should also be nutritious and safe. There is a growing evidence base for contamination of maize and other crops by fungal toxins in the tropics and sub-tropics. As an initial snapshot of contamination by one of these toxins in Rwanda, Aflatoxin B1 (AFB1) was analyzed in 684 samples of maize flour collected in seven principal retail markets of Kigali and in 21 samples of animal feed from seven feed vendors. Two rounds of sample collections were carried out, the first in September 2014 and the second in January 2015. A questionnaire given to vendors was used to determine if gender and education level of vendors, origin of maize and awareness of aflatoxins had any significant effect on AFB1 level in collected samples. Enzyme-Linked Immunosorbent Assay (ELISA) and Immuno-affinity fluorimetery were used to analyze samples. Only markets had a significant effect on AFB1 level; for the two collections, differences were inconsistent among markets. In the first round, market means of AFB1 varied between 8.0 ± 5.57 μg/kg and 24.7 ± 23.74 μg/kg and for the second round, between 10.4 ± 8.4 μg/kg and 25.7 ± 25.85 μg/kg. In most animal feed samples AFB1 was >100 μg/kg. None of the vendors interviewed was aware of the risk of mycotoxin contamination in their maize-based flours and feed. Limits set by the United States Food and Drug Administration (20 μg/kg) for total aflatoxins and European Commission (2 μg/kg) for AFB1 for maize flour imports, were varied between 2–35% and 66–100% of samples, respectively. The implications of this study for human and animal health in Rwanda suggest that expanded surveys are needed to understand the scope of contamination, given the influence of environment and other factors on aflatoxin accumulation. Available options to mitigate and monitor aflatoxin contamination can be further deployed to reduce contamination.     

Aflatoxin B1 in maize harvested over 3 years in Iran

The potential risk of exposure to Aflatoxin B1 (AFB1) is well known. AFB1 contaminations investigated in 373 samples collected during 2006-2008 at harvest stage, from different agro climatic regions of the major maize production area of Iran, including Ardabil (North West), Khuzestan (South West) and Fars at the South of Iran. AFB1 was determined by CD-ELISA and was detected in 146 samples (43.6%), in which only 22.5% were contaminated to higher than MRL level. The amount of aflatoxin in maize samples varied across the years, the percentage of contamination in 2006, 2007 and 2008 were 86.7%, 71.4% and 100% respectively for Ardabil, 63.4%, 41.3% and 24.5% for Khuzestan, 17%, 14.8% and 27.6% for Fars province. The mean of contamination was 15.63, 57.67 and 154.13 μg/kg for Ardabil; 14.41, 35.93 and 1.61 μg/kg for Khuzestan; 0.9, 2.12 and 36.39 μg/kg for Fars province. This is the first report of AFB1 maize contamination to AFB1 in the major maize producing areas of Iran.     

The potential of some spice essential oils in the control of A. parasiticus CFR 223 and aflatoxin production

Essential oils of sweet basil (Ocimum basilicum), cassia (Cinnamomum cassia), coriander (Coriandrum sativum) and bay leaf (Laurus nobilis) at 1–5% (v/v) concentration in palm kernel broth inoculated with spore suspension (10⁶/ml) of Aspergillus parasiticus CFR 223 were evaluated for their potential in the control of aflatoxigenic fungus A. parasiticus CFR 223 and aflatoxin production. Healthy sorghum grains (120/treatment) immersed in the oils and distributed in three petri dishes with wet cotton wool were also inoculated with spore suspension (10⁶/ml) of A. parasiticus CFR 223 and assayed for grain protection. Sweet basil oil at optimal protective dosage of 5% (v/v) was fungistatic on A. parasiticus CFR 223 and aflatoxins produced in vitro and on fungal development on sorghum grains (P ⩽ 0.05) with a residual effect that lasted for 32 days. In contrast, oils of cassia and bay leaf stimulated the mycelia growth of the fungus in vitro but reduced the aflatoxin concentration (B₁ + G₁) of the fungus by 97.92% and 55.21% respectively, while coriander oil did not have any effect on both the mycelia growth and aflatoxin content of the fungus. The combination of cassia and sweet basil oils at half their optimal protective dosages (2.5% v/v) completely inhibited the growth of the fungus. The feasibility of implementing the results of this study to control aflatoxins was examined by the addition of whole and ground dry basil leaves at 5% and 10% (w/w), respectively, to 10 g sorghum, groundnut, maize and melon seed after 35 days storage period. It was found that the addition of whole and ground basil leaves markedly reduced aflatoxin contamination; however, 10% (w/w) of whole leaves was more effective as the reduction in aflatoxin was between 89.05% and 91%.The findings showed that aflatoxins can be controlled by co-storing whole sweet basil leaves with aflatoxin infected foods. The economic value of the study lies in the simplified technique for control of aflatoxin contamination in agricultural products and the benefits derivable from the use of local resources.     

Impact of Pediococcus pentosaceus strain L006 and its metabolites on fumonisin biosynthesis by Fusarium verticillioides

The aim of this work was to study the effectiveness of a Pediococcus pentosaceus strain L006, isolated from maize leaf and previously characterised for its high antifungal efficiency, on fumonisin biosynthesis by Fusarium verticillioides. Studies performed in GYEP medium supplemented with amylopectin showed a significant increase in fumonisin production when the F. verticillioides strain was simultaneously co-inoculated with the P. pentosaceus strain or inoculated in a three-day-old culture of this lactic acid bacteria. Our studies also demonstrated that some extracellular metabolites produced in MRS medium by the P. pentosaceus strain L006 were able to significantly reduce fumonisin production in liquid medium as well as on maize kernels. Fumonisin yields by F. verticillioides inoculated on autoclaved maize kernels were reduced by a factor ranging from 75% to 80% after 20 days of incubation. Our results illustrate the potential risk linked to the use of an antagonistic bacterial agent to manage fumonisin contamination, while emphasizing the potential use of bacterial metabolites to counteract fumonisin accumulation in kernels.     

Aflatoxin M1 in raw,pasteurized and powdered milk available in the Syrian market

The incidence of contamination of aflatoxin M1 (AFM1) in milk samples collected from the Syrian market was investigated by using the competitive enzyme linked immunosorbent assay (ELISA) technique. A total of 126 samples composed of raw cow milk (74 samples), raw sheep milk (23), raw goat milk (11), pasteurized cow milk (10) and powdered milk (8) showed that 80% of tested samples were contaminated with various levels of AFM1 ranging from >20 to 765 ng/l. Percentages of AFM1-contaminated samples exceeding the American, Syrian and European tolerance limits were 22%, 38% and 52%, respectively.The range of contamination was relatively higher in pasteurized milk than in raw cow and sheep milk. 80% of AFM1-contaminated pasteurized cow milk samples exceeded the European tolerance limit with a range of contamination between 89 and 765 ng/l. Percentages of contaminated raw cow, sheep and goat milk exceeding the European tolerance limit were 59%, 24% and 14%, respectively.Milk powder was almost free of AFM1 contamination with only one sample containing a concentration lower than the European tolerance limit (12 ng/l).Extrapolation of aflatoxin B1 (AFB1) from AFM1 levels of contamination in milk samples indicates that contamination in dairy cattle feeds may range from 0.5 to 47.8 μg/kg.     

Multimycotoxin analysis of sorghum (Sorghum bicolor L. Moench) and finger millet (Eleusine coracana L. Garten) from Ethiopia

The natural contamination of sorghum and finger millet by toxigenic fungi and associated mycotoxins has been studied. All the tested sorghum and finger millet samples were found to be contaminated by Fusarium and Aspergillus species. Sorghum was considerably more likely to be contaminated by both genera than finger millet. Penicillium, Alternaria, Rhizopus and Epicoccum species were also present in both grains albeit at lower frequencies. Multimycotoxin analysis using LC–MS/MS revealed the contamination of sorghum and finger millet by 84 and 62 metabolites, respectively. The prevalence of major mycotoxins was lower than 15% in sorghum except zearalenone that occurred in one third of the samples at average level of 44 μg/kg. In finger millet major mycotoxins occurred at a prevalence of 6–52% with zearalenone being the dominant and occurring at average level of 76 μg/kg. Aflatoxins B₁, B₂, G₁, G₂ and M₁ were detected in at least one sorghum sample while only aflatoxins B₁ and G₁ were present in finger millet samples. The average aflatoxins B₁ and G₁ concentrations in sorghum have been higher than European standards. But the level of B₂, G₂ and M₁ in sorghum and that of B₁ and G₁ in finger millet have been lower. Apart from aflatoxin precursors and other Fusarium metabolites, a broad range of additional metabolites were detected in sorghum and finger millet.     

A limited survey of aflatoxin M1 in milk from Indonesia by ELISA

This paper presents a limited survey of aflatoxin M1 (AFM1) in Indonesian milk. AFM1 concentrations of 113 fresh milk samples, collected in 2006 from farms in five different areas of the Yogyakarta Province were analysed. The fresh milk samples were taken directly from dairy farms before pasteurisation. Enzyme-linked immunosorbent assay (ELISA) was used for the analysis of milk samples. Results show that in 48 samples (42.5%) the AFM1 concentrations were less than 5 ng/L and in 31 samples (27.4%) AFM1 was found between 5 and 10 ng/L. In 34 samples (30.1%) the concentrations were above 10 ng/L. None of contaminated samples exceeded the European Union regulation limits of 25 and 50 ng AFM1/L for infant and adult consumption, respectively. Since AFM1 is derived from aflatoxin B1 (AFB1) contained in cow feedstuffs, based on the contamination levels of AFM1 found in this study, the exposure of animals to AFB1 seems to be low.     

Detection of aflatoxin M1 in milk products from China by ELISA using monoclonal antibodies

A rapid and sensitive indirect competitive enzyme-linked immunosorbent assay (ELISA) method using monoclonal antibody for measuring aflatoxin M1 (AFM1) in milk and milk products has been described. One monoclonal antibody was isolated and characterized after fusion of myeloma cells with spleen cells isolated from BALB/c mice that had been immunized with AFM1 carboxymethyl oxime conjugated with bovine serum albumin (BSA). Cross-reactivities of the anti-AFM1 monoclonal antibody clone were 100, 13.9, 6.7 and <1% against AFM1, aflatoxin B1 (AFB1), aflatoxin G1 (AFG1) and deoxynivalenol (DON), respectively. Assays of milk samples mixed with AFM1 ranging in concentration from 0.1 to 3.2 ng/ml gave mean ELISA recovery of 98%. The limit of detection concentration of AFM1 was 0.04 ng/ml. AFM1 contamination was measured in 12 samples of raw milk, 15 samples of powdered milk, 104 samples of liquid milk and four cheese samples collected from different supermarkets in Northeast of China. Of 135 milk samples tested, 55 (41%) samples contained AFM1 at levels that ranged from 0.32–0.50 ng/ml, 24 (18%) samples contained 0.16–0.32 ng/ml, and 18 (13%) samples contained 0–0.16 ng/ml; in 38 (28%) samples AFM1 was not detected. The results indicate that the necessary precaution will have to be taken to minimize the AFM1 contamination in milk and milk products from Northeast of China.     

Development of an aptasensor for the fast detection of Versicolorin A

Aflatoxins (AFs) are secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. The molds may contribute to pre-harvest aflatoxin contamination of susceptible crops. For the customer and food producer, a predictive model for aflatoxin detection is very desirable. Versicolorin A (VerA), which is the first precursor in the pathway of aflatoxin B₁ (AFB₁) biosynthesis, shares similar toxic group with the furofuran structure in aflatoxin B₁. VerA exhibits a much lower teratogenic toxicity than AFB₁ and may be used as a predictive indicator for aflatoxin B₁ contamination of storage crops. Therefore, the development of a fast detection method for VerA is important. One of the randomly computer-generated aptamers of VerA was confirmed by isothermal titration calorimetry with K_d = 9.26 × 10⁻⁶ mol l⁻¹. In addition, a simple and sensitive label-free aptasensor was developed for the electrochemical detection of VerA. According to the results from differential pulse voltammetry (DPV), a linear relationship existed between the log conc. of VerA (ranged from 0.01 to 100 ng ml⁻¹) and the current (△I_p) with a limit of detection (LOD) of 10 pg ml⁻¹. The resulting aptasensor exhibited good reproducibility for detecting VerA and stability after storage for 15 days at 4 °C with acceptable anti-interference against ZEN, OTA, DON, and FB₁. When used in corn samples, the recoveries of VerA were determined to be in the range of 81.3%–104.4 %. Although with some intercross, result suggests that the obtained aptamer for VerA is potentially used as a sorbent for the preparation of solid-phase-extraction procedure to clean up food samples in conjunction with high-performance liquid chromatography analysis.     

Assessing aflatoxin B1 distribution and variability in pistachios: Validation of a Monte Carlo modeling method and comparison to the Codex method

Aflatoxin B1 (AFB1) has genotoxic carcinogenic effects with no threshold. This mycotoxin, produced by Aspergillus fungi species, can be found at a very low incidence in pistachios. More precisely, the contaminant is heterogeneously distributed. Moreover, it is usually found at high concentration levels in contaminated individual nut kernels. For this reason, it is crucial to assess AFB1 distribution and variability accurately in pistachio samples, in order to establish informed sampling schemes for health protection purposes. A modeling method using Monte Carlo simulations for AFB1 distribution in pistachio samples, developed in previous work, required validation. For this purpose, the simulation was adjusted to the distribution observed in 30 kg samples as calculated from the RASFF (Rapid Alert System for Food and Feed) levels reported by Germany for Iranian pistachio imports from September 2002 to September 2004, for the lots tested. As a final result, when the simulated distribution in 10 kg samples was computed from the prior simulation, it was very similar to the distribution observed in representative samples for the same sample size from the RASFF. The simulation method was then compared to another method, for AFB1 distribution and variability assessment, used by the Codex to design aflatoxin sampling plans for tree nuts. Indeed, the distribution observed in 30 kg samples from the RASFF was considered as an input distribution. The output distribution for 10 kg representative samples, as computed using the method, was close to the observed distribution. Results of both simulation methods were very similar. Finally, an extensive comparison of the principles of both methods was performed.     

Fungal contamination and aflatoxin B1 of ‘egusi’ melon seeds in Nigeria

One hundred and thirty seven samples of melon seeds (Colocynthis citrullus L.) from randomly selected farmers’ stores in the humid forest and Northern Guinea savanna of Nigeria were analysed for the incidence of diseased seeds, moisture content, associated moulds and levels of aflatoxin B₁ contamination. The proportion of diseased seeds ranged from 2.5 to 37.3% in the forest and 2.1 to 17.9% in the savanna, while the seed moisture content varied from 5.3 to 10.4%, and 4.6 to 9.5% respectively. All the samples contained moulds, with the two genera, Aspergillus and Penicillium predominating, while A. flavus had the highest species count. The other common fungal isolates in order of decreasing incidence were A. niger, P. citrinum, Botryodiplodia theobromae, Cladosporium sp and A. clavatus. Thin layer chromatography analysis showed that 32% in the forest and 21% samples in the savanna contained aflatoxin B₁ with mean levels of 14.8 μg/kg in the forest and 11.3 μg/kg in the savanna respectively. Significant positive correlations were found between number of aflatoxin B₁ positive samples and the percentage of A. flavus infected samples and between the levels of diseased seeds and the levels of aflatoxin B₁ contamination.     

Determination of aflatoxin levels in some dairy and food products which consumed in Ankara,Turkey

Two hundred and twenty-three samples of dairy products (49 samples of cheese, 94 samples of white cheese, 53 samples of Kashar cheese, and 27 samples of butter), 51 dehulled hazelnut and 40 cacao hazelnut cream, marketed in Ankara, Turkey during September 2002–September 2003, were analysed for aflatoxin M1 (AFM1), total aflatoxin and AFB1 by microtitre plate enzyme-linked immunosorband assay (ELISA). The incidence of AFM1 contamination in dairy products analysed was 90.58%. AFB1 contamination was detected in 43 (84.32%) of dehulled hazelnut samples (ranging from <1 to 10 ppb) and in 38 (95%) samples of cacao hazelnut cream (ranging from <1 to 13 ppb). Total aflatoxin contamination was determined in 47 (92.16%) of dehulled hazelnut samples and in 39 (97.5%) samples of cacao hazelnut cream.AFM1 levels in 19 (8.52%) of 223 dairy product samples were determined higher than maximum tolerable limit of the Turkish Food Codex, whereas total aflatoxin levels in only one of 51 dehulled hazelnut and one of 40 hazelnut cacao cream samples were exceeded the legal limit.Continuous surevillance programme may be warranted to monitor regularly the occurrence of aflatoxins in foods and foodstuffs which consumed by human.     

Inactivation of Aspergillus flavus spores by curcumin-mediated photosensitization

Minimizing fungal infection is essential to the control of mycotoxin contamination of foods and feeds but many potential control methods are not without their own safety concerns for the consumers. Photodynamic inactivation is a novel light-based approach which offers a promising alternative to conventional methods for the control of mycotoxigenic fungi. This study describes the use of curcumin to inactivate spores of Aspergillus flavus, one of the major aflatoxin producing fungi in foods and feeds. Curcumin is a natural polyphenolic compound from the spice turmeric (Curcuma longa). In this study the plant has shown to be an effective photosensitiser when combined with visible light (420 nm). The experiment was conducted in in vitro and in vivo where A. flavus spores were treated with different photosensitiser concentration and light dose both in buffer solution and on maize kernels. Comparison of fungal load from treated and untreated samples was determined, and reductions of fungal spore counts of up to 3 log CFU ml⁻¹ in suspension and 2 log CFU g⁻¹ in maize kernels were obtained using optimal dye concentrations and light dose combinations. The results in this study indicate that curcumin-mediated photosensitization is a potentially effective method to decontaminate A. flavus spores in foods and feeds.     

Occurrence of aflatoxin contamination in maize throughout the supply chain in the Democratic Republic of Congo

Aflatoxin occurs ubiquitously in maize and is both an economic and a public health concern due to its carcinogenic effects. Nevertheless, in developing countries such as the Democratic Republic of Congo, there is still a dearth of information regarding its natural occurrence, exposure to both humans and animals and strategies for controlling its proliferation or contamination of food crops such as maize. The present study comparatively assessed the aflatoxin occurrence in maize samples collected in the DRC throughout the food supply chain. The analytical method used during this experiment was found to be accurate with a recovery ranging between 70.65 and 98.20%, and also precise (RSD<15%) except for AFG₁, which showed an RSD of 18.05%. Moreover, the limits of detection (LOD) and quantification (LOQ) for aflatoxin ranged from 0.31 to 0.69 μg/kg and from 1 to 2 μg/kg, respectively. The results also revealed that in the pre-harvest period, 32% of maize samples (out of a total of 50) were positive, with aflatoxins at a range of 1.5–51.23 μg/kg for AFB1 and 3.1–103.89 μg/kg for total aflatoxin. As the supply chain progresses, the contamination of maize samples also increases, with 100% of the collected maize samples found to contain aflatoxins at 300 times higher than the maximum limit of 10 μg/kg for total aflatoxin as set by the WHO. The aflatoxin content of maize samples was found to increase drastically at up to 500 times between the city store and the distribution system at market level. This was confirmed with a statistical analysis showing a significant difference (p < 0.01) between city store/market samples and pre-harvest, harvest, farm store and after-transportation samples.     

Aflatoxin M1 contamination in pasteurized milk in Shiraz (south of Iran)

The aim of this study was to evaluate Aflatoxin M1 (AFM1) contamination in pasteurized milk samples in Shiraz city (Iran). Six hundred and twenty four pasteurized milk samples from different supermarkets in Shiraz city were collected during 6 months (April to September 2003). AFM1 was found in 100% of the examined milk samples. 17.8% of the samples had AFM1 greater than the maximum tolerance limit (50 ng/l) accepted by European Union. Contamination with AFM1 is a serious problem for public health. To achieve a low level of AFM1 in milk, cows’ feed samples from various cowsheds must be evaluated routinely for aflatoxin and kept away from fungal contamination as much as possible.