A survey of ethnic foods for microbial quality and aflatoxin content

Recent advancements on use of essential oils as preservatives against fungi and mycotoxins spoiling food grains

Spoilage of grains by mycotoxigenic fungi poses a great threat to food security and human health. Conventionally used chemical agents to prevent grain fungi contamination cause increasingly significant problems such as microbial resistance, residual toxicity and environmental unfriendliness. In recent years, plant essential oils (EOs) have become a hot spot in the research of control of grain fungi and mycotoxins, due to their extensive sources, non-toxicity, environmental friendliness and good antifungal efficiency. The current review aims to provide an overview of the prevention of fungi and mycotoxins in grain through EOs. The antifungal and toxin inhibition efficiency of different EOs and their effective components are investigated. The inhibition mechanism of EOs on fungi and mycotoxins in grains is introduced. The influence of EOs treatment on the change of grain quality is also discussed. In addition, the formulations and techniques used to overcome the disadvantages of EOs application are introduced. The results of recent studies have confirmed that EOs provide great potential for controlling common fungi and mycotoxins in grains, and enhancing quantity and quality safety of grains.

Study on inhibitory activity and mechanism of chitosan oligosaccharides on Aspergillus Flavus and Aspergillus Fumigatus

Chitosan oligosaccharides (COS) are a derivative of low molecular weight chitosan and are potent natural antimicrobial agents. The antimicrobial activity of COS against Aspergillus flavus and Aspergillus fumigatus was evaluated by minimum inhibitory concentration (MIC) and inhibition of mycelial growth. The MICs of COS against these two fungi were 31.2 and 15.6 mg/mL, respectively. COS treatment rendered fungal mycelia wrinkled and deformed with a fractured appearance. COS also increased cellular permeability leading to a significant leakage of cellular components indicating membrane damage. This compound also dose-dependently reduced chitin production and enhanced chitinase activity while enhancing the accumulation of reactive oxygen species (ROS). These characteristics suggested that COS has inhibitory effects against food spoilage fungi and acts on the cell wall and membrane and alters cellular metabolism. COS shows promise for food industry applications since it is non-toxic to higher organisms.

Fungal diversity of "solom" a Ghanaian traditional beverage of millet (Pennisetum glaucum)

The association of cereals with fungi cannot be disregarded as their manifestation in our foods poses serious health risks. The aim of this study was to investigate the mycofloral (fungal) and chemical (pH) qualities of the "solom" (beverage of millet) available for consumption from their respective sales points in Ho. "Solom" a cereal beverage of millet was sampled from ten (10) different locations in the Ho Municipality of Ghana and evaluated for their pH, fungal counts, and species diversity. Mycological analyses were done on Oxytetracycline Glucose Yeast Extract (OGYE) and Dichloran Rose Bengal Chloramphenicol (DRBC) media from three (3) points per location using serial dilution. A total of fourteen (14) fungal species belonging to eight (8) genera were isolated on both media; Aspergillus (A. niger, A. flavus, A. fumigatus, A. parasiticus, A. alutaceaus, A. terreus), Rhizopus (R. stolonifer), Mucor (M. racemosus), Fusarium (F. oxysporum), Penicillium (P. digitatum, P. verucosum), Cladosporium (C. cladosporoides), Curvularia (C. lunata), and Rhodotorula sp. were recorded. Fungal counts on both media ranged between 1.68 ± 0.8 and 4.11 ± 0.9 log10 CFU/ml. There were statistically significant (p < .05) differences observed in the samples from different locations. The values of pH recorded were in the range of 3.03 ± 0.09-4.03 ± 0.23 and showed no significant differences (p > .05) among them. All samples were found to be in the acceptable range of values prescribed by the International Commission for Microbiological Specification of Foods (ICMSF, 1998). Good Manufacturing Practices (GMP) and Good Hygiene Practices (GHP) should be employed to enhance food safety.

Bacterial and heavy metal contamination in selected commonly sold herbal medicine in Blantyre, Malawi

Background

There has been an increase in use of herbal medicine worldwide. It is either used as a stand-alone or complementary therapy to conventional medicine due to past good experience, poverty and family traditions. In Malawi, there are no regulations governing the supply, acquisition, marketing and quality enforcement of herbal medicine. This compromises its safety thereby exposing consumers to avoidable bacteria and heavy metals leading to various adverse health effects.

Methods

Cross-sectional laboratory experiments were conducted to determine bacterial and heavy metal contamination of herbal medicine commonly sold in Blantyre, Malawi. A total of 47 samples which were in three formulations namely liquid, powder and tablet were used in the experiments. 29 samples were used for bacterial limit tests and 18 samples were used for heavy metal analysis. Bacterial contamination was determined by streak plate method and biochemical tests while heavy metals were determined by atomic absorption spectroscopy. Descriptive statistics and t-tests were calculated using Microsoft excel and SPSS software programs.

Results

Twenty out of the 29 samples (68.9%) were contaminated with Bacillus, coagulase negative Staphylococcus, Klebsiella, Enterobacter, Citrobacter and other-Coliform bacterial species. Most isolated microorganism was Citrobacter spp. (30%), followed by Bacillus spp. (25%). Out of 20 contaminated samples, 75% were contaminated with coliforms. From these 75% which were contaminated with coliforms, 93.3% of them exceeded WHO regulatory limit (103 CFU/g for enterobacteria). Although liquid samples had the highest level of bacterial contaminants, the count was not statistically different from other formulations (P = 0.058). For heavy metals, lead and cadmium were detected and 67% of the samples had lead levels exceeding regulatory limits.

Conclusion

Levels of bacterial and lead contamination in herbal medicine from Blantyre markets are far above acceptable limits set by WHO and Canadian guidelines. The use of these herbal medicines is a major risk to the health of consumers.

Microbial contamination in herbal medicines: a serious health hazard to elderly consumers

Introduction

The use of herbal medicine is on the rise worldwide, and safety issues associated with herbal medicines may have an exacerbated impact in elderly because this population has an increased susceptibility and sensitivity to health complications due to the aging process.

Methods

This cross-sectional study was carried out at a primary health care unit in the city of Macapa, Brazil. The herbal medicines used and the sociodemographic characteristics of 123 voluntarily consenting participants were collected using a structured questionnaire. A total of 132 herbal medicines with oral or topical administration were donated by the elderly for microbial analysis before consumption, and 18 water samples used in the preparation of homemade herbal medicines were collected. Bacterial and fungal counts and identification of bacterial pathogens (Escherichia coli, Salmonella spp., Pseudomonas aeruginosa and Staphylococcus aureus) were performed according to the regulations of the Brazilian Pharmacopoeia and World Health Organization. Water analysis for the detection of coliforms and E. coli was carried out using Colilert® according to the manufacturer’s instructions and the techniques established by Standard Methods.

Results

Of the study participants, 78.8% were women. Bacterial growth was observed in samples from 51.5% of study and 35.6% had fungal growth. A total of 31.8% of the herbal medicine samples exceeded the safety limits (CFU/g ≤ 10⁵), including 16.7% of the homemade herbal medicines and 15.1% of the commercial herbal medicines. It was also found that 31.0% of the samples exceeded the safety limit for fungal growth. The microorganisms most commonly isolated from the herbal medicines were S. aureus (49.2%), followed by Salmonella spp. (34.8%), E. coli (25.8%), and P. aeruginosa (14.4%). Of water samples analyzed, 77.8% were positive for total coliforms (1 ml) and in 66.7% water samples E. coli was detected (1 ml), making them unfit for consumption.

Conclusions

The use of homemade and commercial herbal medicines is a major risk to the health of elderly who use these therapies due to the lack of microbial quality standards. We observed levels of viable bacteria and fungi that were above safety limits; in addition, we were able to isolate pathogenic bacteria from these herbal medicines.

Overview of Fungi and Mycotoxin Contamination in Capsicum Pepper and in Its Derivatives

Capsicum products are widely commercialised and consumed worldwide. These substrates present unusual nutritional characteristics for microbial growth. Despite this, the presence of spoilage fungi and the co-occurrence of mycotoxins in the pepper production chain have been commonly detected. The main aim of this work was to review the critical control points, with a focus on mycotoxin contamination, during the production, storage and distribution of Capsicum products from a safety perspective; outlining the important role of ecophysiological factors in stimulating or inhibiting mycotoxin biosynthesis in these food commodities. Moreover, the human health risks caused by the ingestion of peppers contaminated with mycotoxins were also reviewed. Overall, Capsicum and its derivative-products are highly susceptible to contamination by mycotoxins. Pepper crop production and further transportation, processing and storage are crucial for production of safe food.

Antifungal Activity of Essential Oil Compounds (Geraniol and Citral) and Inhibitory Mechanisms on Grain Pathogens (Aspergillus flavus and Aspergillus ochraceus)

The grain contamination by Aspergillus spp. has been a serious issue. This study exhibited the excellent antifungal effects of the essential oil compounds (EOCs) geraniol and citral against common grain pathogens (A. flavus and A. ochraceus) in vitro and in situ. The inhibitory mechanisms were also evaluated from the perspective of cell membrane permeability, reactive oxygen species (ROS) generation, and Aspergillus spp. growth-related gene expression. Meanwhile, the combined effects of EOCs in the vapor phase and modified atmosphere packaging (MAP) were examined to find an alternative preservation method for controlling Aspergillus spp. The results indicated that citral exhibited the antifungal activity mainly by downregulating the sporulation- and growth-related genes for both pathogens. Geraniol displayed inhibitory effectiveness against A. flavus predominantly by inducing the intracellular ROS accumulation and showed toxicity against A. ochraceus principally by changing cell membrane permeability. Furthermore, the synthetic effects of EOCs and MAP (75% CO₂ and 25% N₂) induced better grain quality than the current commercial fumigant AlP. These findings reveal that EOCs have potential to be a novel grain preservative for further application.

Analysis of enterotoxigenic Bacillus cereus strains from dried foods using whole genome sequencing, multi-locus sequence analysis and toxin gene prevalence and distribution using endpoint PCR analysis

Bacillus cereus strains were isolated from dried foods, which included international brands of spices from South East Asia, Mexico and India purchased from several retail stores, samples of powdered infant formula (PIF), medicated fish feed and dietary supplements. The genetic diversity of 64 strains from spices and PIF was determined using a multiplex endpoint PCR assay designed to identify hemolysin BL, nonhemolytic enterotoxin, cytotoxin K, and enterotoxin FM toxin genes. Thirteen different B. cereus toxigenic gene patterns or profiles were identified among the strains. Randomly selected B. cereus strains were sequenced and compared with reference Genomic Groups from National Center Biotechnology Information using bioinformatics tools. A comprehensive multi-loci sequence analysis (MLSA) was designed using alleles from 25 known MLST genes specifically tailored for use with whole genome assemblies. A cohort of representative genomes of strains from a few FDA regulated commodities like dry foods and medicated fish feed was used to demonstrate the utility of the 25-MLSA approach for rapid clustering and identification of Genome Groups. The analysis clustered the strains from medicated fish feed, dry foods, and dietary supplements into phylogenetically-related groups. 25-MLSA also pointed to a greater diversity of B. cereus strains from foods and feed than previously recognized. Our integrated approach of toxin gene PCR, and to our knowledge, whole genome sequencing (WGS) based sequence analysis, may be the first of its kind that demonstrates enterotoxigenic potential and genomic diversity in parallel.

Risk of Fungi Associated with Aflatoxin and Fumonisin in Medicinal Herbal Products in the Kenyan Market

Utilization of herbal products is a major concern due to the possibility of contamination by toxigenic fungi that are mycotoxin producers such as Aspergillus species during processing and packaging. Research was carried out to determine the presence of aflatoxins and fumonisins in herbal medicinal products sold in Eldoret and Mombasa towns in Kenya. The study employed both exploratory and laboratory experimental design. The herbal products were purchased from the market and transported to Kenya Medical Research Institute for processing and analysis. Fungal contaminants were determined according to Pharmacopoeia specifications. The toxins were quantified using ELISA based technique. The genus Aspergillus was the most dominant followed by Penicillium. Fungal counts ranged between 1 CFU/g and >1000 cfu/g. Analysis of variance showed that the rate of fungal contaminants for Eldoret and Mombasa samples had significant association (p ≤ 0.001). Aflatoxin levels ranged from 1 to 24 ppb, while fumonisin levels ranged from 1 to >20 ppb. Only 31% of samples met the standards for microbial limits as specified in Pharmacopoeia. There is need for product microbial quality improvement through proper harvesting, processing, storage, and marketing. It is recommended that a policy be enacted to enable regulation of herbal products in Kenya.

Identification of bacterial contaminants in polyherbal medicines used for the treatment of tuberculosis in Amatole District of the Eastern Cape Province, South Africa, using rapid 16S rRNA technique

BACKGROUND

Polyherbal medicines are used for the treatment of many diseases in many African and Asian communities. With the increasing use of these remedies, several investigations have shown that they are associated with a broad variety of residues and contaminants. This study investigates the presence of bacteria in the polyherbal medicines used for the treatment of tuberculosis (TB) in the Eastern Cape Province of South Africa.

METHODS

Bacterial DNA was extracted from the polyherbal medicines, and a fragment of the bacterial 16S rRNA gene was amplified by PCR with universal primers 27F and 518R. The amplicons were visualised on agarose gel electrophoresis, followed by end repair and adaptor ligation. They were further purified and quantified using Library Preparation kit NEBNext® UltraT DNA Library Prep Kit for Illumina, and the amplicons were run on illumina's MiSeq platform.

RESULTS

Different bacterial species were identified in all each of the polyherbal medicines. Generally, the most prominent and common bacteria recovered from all the samples were Bacillus sp., Enterobacter sp., Klebsiella sp., Rahnella sp., Paenibacillus sp., Clostridium sp. and Pantoea sp. Others are Pseudomonas sp., Raoultella ornithinolytica, Salmonella enterica and Eubacterium moniliforme.

CONCLUSIONS

This study, thus, revealed the presence of pathogenic and non-pathogenic bacteria in the polyherbal medicines used for the treatment of tuberculosis in the study area. The implications of the findings are discussed in relation to the health care of the patients of tuberculosis in the study area, having in mind that they are immunocompromised individuals.

Prevalence and Amounts of Salmonella Found on Raw California Inshell Pistachios

After harvest, pistachios are hulled with mechanical abrasion and then separated in a float tank containing water; the nuts that float (∼15%; floaters) and those that sink (∼85%; sinkers) are dried and stored separately. To determine the prevalence of Salmonella in pistachios, a total of 3,966 samples (1,032 floaters and 2,934 sinkers) were collected within 4 months of the 2010, 2011, and 2012 harvests from storage silos (12 samples from each silo, in most cases) and were stored at 4°C; 100-g subsamples were enriched for the presence of Salmonella. Twenty-one of the floater samples and 11 of the sinker samples were positive for Salmonella: 2.0% prevalence (95% confidence interval [CI], 1.3 to 3.1%) and 0.37% prevalence (95% CI, 0.21 to 0.67%), respectively, for a weighted average prevalence of 0.61%. Levels of Salmonella were determined for positive samples using a most-probable-number (MPN) method with multiple 50-g, three 5.6-g, and three 0.56-g subsamples. Geometric mean levels of Salmonella in floaters and sinkers were 0.66 MPN/100 g (0.14 to 5.3 MPN/100 g) and 0.18 MPN/100 g (0.10 to 0.62 MPN/100 g), respectively. Seven different serovars were identified among the isolates, with nine pulsed-field gel electrophoresis fingerprints; as many as four serovars were isolated from some samples. Salmonella serovars Montevideo (44%), Enteritidis (19%), Senftenberg (16%), Worthington (12%), and Liverpool (9.4%) were most commonly isolated from the initial 100-g samples. The prevalence and levels of Salmonella in pistachios are within those observed for other tree nuts, but the limited number of serovars isolated suggests a narrow and persistent contamination source.

Serum aflatoxin levels of the healthy adult population living in the north and south regions of Turkey

OBJECTIVE

To determine the serum concentrations of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) in the healthy adult population living in both the Black Sea and Mediterranean regions of Turkey and to investigate the regional, seasonal and gender variability in aflatoxins (AF) exposure in these regions.

DESIGN

Serum AFB1, AFB2, AFG1 and AFG2 concentrations were analysed by HPLC. Settings In total, four hundred and eighty-four serum samples were analysed.

SUBJECTS

Four hundred and eighty-four healthy adult volunteers living in rural areas of the Black Sea and Mediterranean regions of Turkey were studied.

RESULTS

The mean serum concentration of total AF in the Black Sea region was 1·33 ppb (min-max 0·15-3·38 ppb) and 0·90 ppb (min-max 0·18-2·48 ppb) for summer and winter, respectively. In the Mediterranean region, the mean serum concentration of total AF was determined as 0·55 ppb (range 0·04-1·72 ppb) for summer and 0·45 ppb (range 0·12-1·43 ppb) for winter. The total AF concentrations in serum samples were statistically higher in summer compared with winter for the two regions. The differences between the regions were statistically significant concerning all samples, with higher total AF concentrations in the Black Sea region.

CONCLUSIONS

The overall results suggest that the Turkish population living in these two regions is continuously exposed to AF, particularly in the summer, and that mycotoxin contamination in food should be monitored routinely for food safety and human health.

Level of Chemical and Microbiological Contaminations in Chili Bo (Paste)

The objective of this study was to determine the level of preservatives and microbiological loads in various brands of commercially available chili bo (paste). Fifteen different brands of chili bo obtained from the local market and hypermarkets were analyzed for pH, moisture and benzoic acid content, microbiological loads (aerobic, anaerobic, aerobic spores, and fungi), and thermophilic microorganisms. Results showed that both moisture content and pH vary among samples. The concentrations of benzoic acid detected in chili bo were found to be in the range of 537 to 5,435 mg/kg. Nine of fifteen brands were found to exceed the maximum level permitted by the Malaysian Food Law in accordance with the Codex Alimentarius (1,000 mg/kg for benzoic acid). An apparent correlation between benzoic acid concentration and microbiological loads present in the chili bo was observed. The microbiological loads were found to be relatively low in the end products containing high amounts of benzoic acid. The heat-resistant (70 to 80°C) microorganisms present in chili bo were identified as Ochrobacterum tritici, Stenotrophomonas rhizophila, Microbacterium maritypicum, Roseomonas spp., CDC group II-E subgroup A, Flavimonas oryzihabitans, and Pseudomonas aeruginosa, with M. maritypicum being the most frequently found (in 9 of 15 samples) microorganism. Most of these identified microorganisms were not known to cause foodborne illnesses.

Aflatoxins evaluation on in-shell and shelled dry Brazil nuts for export analysed by LC-MS/MS - 2006 and 2007 harvests

Dry in-shell and shelled Brazil nuts from two different harvests were evaluated for aflatoxins by LC-tandem mass spectrometry with atmospheric pressure chemical ionisation in the positive mode. A total of 171 samples of Brazil nuts for export, comprising 108 in-shell and 63 shelled (large, medium and small sizes) were collected in a factory located at Manaus city, State of Amazonas, in the Brazilian Amazon. They were collected from big bags (in-shell nuts) and sorting tables after size classification (shelled nuts), immediately after processing, from April to May of 2006 and 2007. Samples also had their moisture content (mc) and water activity (aw) analysed and the out- and in-door environmental conditions (relative humidity (RH) and temperature) were monitored during the sampling period. From all the samples analysed from both harvests, only 8.7% (14) of the nuts contained aflatoxin at levels >4 µg/kg (EU maximum level). This corresponded to a total number of 11 and 3 for the in-shell and shelled nuts, respectively. The 2007 harvest nuts had fewer samples with aflatoxin levels higher than 4 mg/kg, with 2 for both in-shell and shelled nuts each. The analytical method was selective, sensitive and fast (total run time of 7 min). The RH in the factory ranged from 77.1 to 95.8% (2006) and 76.9 to 91.0% (2007) being the highest RH reached in April. The data showed that the nuts' aflatoxin levels varied with the year of harvest and cleared up the speculation about which type of dried nut has aflatoxin levels safe enough for commercialisation.

Risk assessment for Clostridium perfringens in ready-to-eat and partially cooked meat and poultry products

An assessment of the risk of illness associated with Clostridium perfringens in ready-to-eat and partially cooked meat and poultry products was completed to estimate the effect on the annual frequency of illnesses of changing the allowed maximal 1-log growth of C. perfringens during stabilization (cooling after the manufacturing heat step). The exposure assessment modeled stabilization, storage, and consumer preparation such as reheating and hot-holding. The model predicted that assuming a 10- or 100-fold increase from the assumed 1-log (maximal allowable) growth of C. perfringens results in a 1.2- or 1.6-fold increase of C. perfringens-caused illnesses, respectively, at the median of the uncertainty distribution. Improper retail and consumer refrigeration accounted for approximately 90% of the 79,000 C. perfringens illnesses predicted by the model at 1-log growth during stabilization. Improper hot-holding accounted for 8% of predicted illnesses, although model limitations imply that this is an underestimate. Stabilization accounted for less than 1% of illnesses. Efforts to reduce illnesses from C. perfringens in ready-to-eat and partially cooked meat and poultry products should focus on retail and consumer storage and preparation methods.

Capsicum and Mycotoxin Contamination: State of the Art in a Global Context

Owing to their usual conditions of production in countries with warm and humid climates and to poor storage conditions, products derived from Capsicum sp. are susceptible to fungal contamination and development, which can lead to the accumulation of mycotoxins in these foods. Thus, products as chilli or paprika can be contaminated with fungal toxins, such as aflatoxins, ochratoxins and other mycotoxins, which pose a serious risk to public health. This study reviews the main aspects regarding mycotoxin contamination of Capsicum, in the context of the importance of this product in a global market and approaches the effect of processing on final contamination of foods, as well as reviews the analytical methodology commonly employed in fungal and mycotoxin analysis in these types of products.

Estado de frescor e qualidade higiênica do pescado vendido numa cidade do interior de Portugal

Avaliaram-se o estado de frescor e a qualidade higiênica do pescado disponível em alguns estabelecimentos comerciais de Vila Real, uma cidade do interior de Portugal. Vinte e três amostras foram submetidas a uma análise sensorial e a análises fisico-químicas - determinação do teor de azoto básico volátil total (ABVT), do índice de refração do humor aquoso e do pH. A avaliação da qualidade higiênica do pescado foi feita por meio de diferentes análises microbiológicas na superfície e na profundidade do músculo do pescado. O pescado fresco, considerado por todos os métodos de análise, próprio para consumo, apresentou estado de frescor entre bom e satisfatório. O ABVT foi considerado o método objetivo de eleição, sempre que surgiram dúvidas relativamente ao grau de frescor do pescado. O pescado próprio para consumo apresentou valores que variaram entre os 20,60 e 27,36mgN/100g e perfil microbiológico aceitável, com contagens de microrganismos psicrotróficos entre 5,41 e 6,03 UFC/cm² na superfície e entre 4,79 e 5,28 UFC/cm² no músculo.

Multiple correspondence analysis and random amplified polymorphic DNA molecular typing to assess the sources of Staphylococcus aureus contamination in alheira production lines

Sources and tracing of Staphylococcus aureus in alheira (garlic sausage) production were evaluated by multifactorial correspondence analysis (MCA) of occurrence data and a random amplified polymorphic DNA (RAPD) on S. aureus isolates. Samples from four production lines, four different production batches, and 14 different sampling sites (including raw material, different contact surfaces, and several stages of alheira manufacturing) were analyzed at four sampling times. From the 896 microbial analyses completed, a collection of 170 S. aureus isolates was obtained. Although analysis of the occurrence data alone was not elucidative enough, MCA and RAPD-PCR were able to assess the sources of contamination and to trace the spread of this microorganism along the production lines. MCA results indicated that the presence of S. aureus in alheira was related to its presence in the intermediate manufacturing stages after heat treatment but before stuffing in the casings. It was also possible to associate a cross-contamination path related to handler procedures. RAPD-PCR typing in accordance to MCA results confirmed the cross-contamination path between the raw material and casings and the role of handlers as an important cross-contamination vehicle.

Occurrence of aflatoxin M1in randomly selected North African milk and cheese samples

Forty-nine samples of raw cow's milk and 20 samples of fresh white soft cheese were collected directly from 20 local dairy factories in the north-west of Libya and analysed for the presence of aflatoxin M1 (AFM1). The samples were analysed using a high-performance liquid chromatography technique for toxin detection and quantification. Thirty-five of the 49 milk samples (71.4%) showed AFM1 levels between 0.03 and 3.13 ng ml(-1) milk. Multiple analyses of five milk samples free of AFM1 artificially contaminated with concentrations of AFM1 at 0.01, 0.05, 0.1, 1.0 and 3.0 ng ml(-1) showed average recoveries of 66.85, 72.41, 83.29, 97.94 and 98.25%, with coefficients of variations of 3.77, 4.11, 1.57, 1.29 and 0.54%, respectively. Fifteen of 20 white soft cheese samples (75.0%) showed the presence of AFM1 in concentrations between 0. 11 and 0.52 ng g(-1) of cheese. Multiple assays of five cheese samples free of AFM1 spiked with different concentration of AFM1 (0.1, 0.5, 1.0 and 3.0 ng g(-1)) showed average recoveries of 63.23, 78.14,83.29 and 88.68%, with coefficients of variation of 1.53, 9.90, 4.87 and 3.79%, respectively. The concentrations of AFM1 were lower in the cheese products than in the raw milk samples.

Determination of aflatoxins in peanuts by matrix solid-phase dispersion and liquid chromatography

A new method based on matrix solid-phase dispersion (MSPD) extraction was studied to determine aflatoxin B1, B2, G1 and G2 from peanuts. Optimization of different parameters, such as type of solid supports for matrix dispersion and elution solvents were carried out. The method used 2 g of peanut sample, 2 g of C18 bonded silica as MSPD sorbent and acetonitrile as eluting solvent. Recoveries of each aflatoxin spiked to peanut samples at 2.5 ng/g (5 ng/g for aflatoxin G2) level were between 78 and 86% with relative standard deviations ranging from 4 to 7%. The limits of quantification ranged from 0.125 to 2.5 ng/g for the four studied aflatoxins using liquid chromatography (LC) with fluorescence detection. In addition, LC coupled to mass spectrometry with an electrospray interface was used for confirmation of aflatoxins present in real samples. Eleven peanut samples from different countries were analyzed by the proposed method and by using an enzyme-linked immunosorbent assay (ELISA). ELISA test is a good screening method for investigation of these mycotoxins in peanut samples.