7 research outputs found

    Polyphasic approach to the identification and characterization of aflatoxigenic strains of Aspergillus section Flavi isolated from peanuts and peanut-based products marketed in Malaysia

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    Peanuts are widely consumed as the main ingredient in many local dishes in Malaysia. However, the tropical climate in Malaysia (high temperature and humidity) favours the growth of fungi from Aspergillus section Flavi, especially during storage. Most of the species from this section, such as A. flavus, A. parasiticus and A. nomius, are natural producers of aflatoxins. Precise identification of local isolates and information regarding their ability to produce aflatoxins are very important to evaluate the safety of food marketed in Malaysia. Therefore, this study aimed to identify and characterize the aflatoxigenic and non-aflatoxigenic strains of Aspergillus section Flavi in peanuts and peanut-based products. A polyphasic approach, consisting of morphological and chemical characterizations was applied to 128 isolates originating from raw peanuts and peanut-based products. On the basis of morphological characters, 127 positively identified as Aspergillus flavus, and the other as A. nomius. Chemical characterization revealed six chemotype profiles which indicates diversity of toxigenic potential. About 58.6%, 68.5%, and 100% of the isolates are positive for aflatoxins, cyclopiazonic acid and aspergillic acid productions respectively. The majority of the isolates originating from raw peanut samples (64.8%) were aflatoxigenic, while those from peanut-based products were less toxigenic (39.1%). The precise identification of these species may help in developing control strategies for aflatoxigenic fungi and aflatoxin contamination in peanuts, especially during storage. These findings also highlight the possibility of the co-occurrence of other toxins, which could increase the potential toxic effects of peanuts

    Prevalence of Aspergillus spp. and occurrence of aflatoxins in peanut sauce processing by peanut sauce manufacturers

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    The aims of the present work were to determine the prevalence of Aspergillus spp. and occurrence of aflatoxins (AFs) along the peanut sauce processing line from different peanut sauce companies in Malaysia, and to determine to which extent peanut sauce processing steps employed by the peanut sauce industries could efficiently reduce AFs in peanut sauce. Peanut and chili samples were collected at each processing step along the peanut sauce production from three peanut sauce companies which were different in companies’ profile. Peanut samples from Companies B (87.5%) and C (100%) were contaminated with AFs. Of these, 12.5% (Company B) and 75% (Company C) samples exceeded the Malaysian regulatory limit. None of the samples from Company A was contaminated. The steps efficient in reducing AFs in peanut sauce identified in the present work were (i) safety monitoring of raw materials, (ii) sorting of raw materials, and (iii) heat treatment of raw materials

    Evaluation of aflatoxin and Aspergillus sp. contamination in raw peanuts and peanut-based products along this supply chain in Malaysia

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    The peanut supply chain in Malaysia is dominated by three main stakeholders (importers, manufacturers, retailers). The present study aimed to determine the levels and critical points of aflatoxin and fungal contamination in peanuts along the supply chain. Specifically, two types of raw peanuts and six types of peanut-based products were collected (N = 178). Samples were analysed for aflatoxins by using high-performance liquid chromatography. Results revealed that the aflatoxin contamination was significantly higher (P ≤ 0.05) in raw peanuts and peanut-based products from the retailers. However, there was no significant difference (P ≥ 0.05) in fungal contamination for both types of peanuts except for the total fungal count in raw peanuts from the retailers. Furthermore, raw peanut kernels from the retailers were the most contaminated ones ranged from <LOD to 1021.4 µg/kg (mean: 120.7 µg/kg, median: 1.4 µg/kg) followed by the samples collected from the manufacturers which was ranged from < LOD to 181.9 µg/kg (mean: 20.5 µg/kg, median: 0.0 µg/kg). About 38% and 22% of the samples from the retailers and manufacturers were found to have exceeded the Malaysian Regulation limit (raw peanuts:15 µg/kg; peanut-based products:10 µg/kg), respectively. In contrast, no aflatoxins were detected in samples from the importers. On the other hand, 15.0% and 5.9% of peanut-based products from retailers and manufacturers, respectively, were found to have exceeded the limit. Fungal contamination (0.3–3.6 log CFU/g) was relatively higher in raw peanuts compared to that of peanut-based products (0.6–2.7 log CFU/g). In conclusion, the manufacturers and retailers were the critical points for aflatoxin contamination in peanuts. However, fungal contamination was more critical in the raw peanuts compared to peanut-based products. The study was limited by a minimal number of samples from the importer. Therefore, further investigations on a larger sample size should be conducted to confirm the findings in this present study

    Determination of organochlorine and pyrethroid pesticides in fruit and vegetables using solid phase extraction clean-up cartridges.

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    A method to determine six organochlorine and three pyrethroid pesticides in grape, orange, tomato, carrot and green mustard based on solvent extraction followed by solid phase extraction (SPE) clean-up is described. The pesticides were spiked into the sample prior to analysis, extracted with ethyl acetate, evaporated and reconstituted with a solvent mixture of acetone:n-hexane (3:7). Three different sorbents (Strong Anion Exchanger/Primary Secondary Amine (SAX/PSA), Florisil and C18) were used for the clean-up step. Pesticides were eluted with 5mL of acetone:n-hexane (3:7, v/v) and determined by gas chromatography and electron-capture detection (GC–ECD). SAX/PSA was the sorbent, which provided chromatograms with less interference and the mean recoveries obtained were within 70–120% except for captafol. The captafol recoveries for grape were within acceptable range with C18 clean-up column

    Molecular characterisation of aflatoxigenic and non-aflatoxigenic strains of Aspergillus section Flavi isolated from imported peanuts along the supply chain in Malaysia

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    Peanuts are widely consumed in many local dishes in southeast Asian countries, especially in Malaysia which is one of the major peanut-importing countries in this region. Therefore, Aspergillus spp. and aflatoxin contamination in peanuts during storage are becoming major concerns due to the tropical weather in this region that favours the growth of aflatoxigenic fungi. The present study thus aimed to molecularly identify and characterise the Aspergillus section Flavi isolated from imported peanuts in Malaysia. The internal transcribed spacer (ITS) and β-tubulin sequences were used to confirm the species and determine the phylogenetic relationship among the isolates, while aflatoxin biosynthesis genes (aflR, aflP (omtA), aflD (nor-1), aflM (ver-1), and pksA) were targeted in a multiplex PCR to determine the toxigenic potential. A total of 76 and one isolates were confirmed as A. flavus and A. tamarii, respectively. The Maximum Likelihood (ML) phylogenetic tree resolved the species into two different clades in which all A. flavus (both aflatoxigenic and non-aflatoxigenic) were grouped in the same clade and A. tamarii was grouped in a different clade. The aflatoxin biosynthesis genes were detected in all aflatoxigenic A. flavus while the non-aflatoxigenic A. flavus failed to amplify at least one of the genes. The results indicated that both aflatoxigenic and non-aflatoxigenic A. flavus could survive in imported peanuts and, thus, appropriate storage conditions preferably with low temperature should be considered to avoid the re-emergence of aflatoxigenic A. flavus and the subsequent aflatoxin production in peanuts during storage
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