Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.986
Filtrar
1.
Anal Bioanal Chem ; 412(4): 895-904, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31900533

RESUMO

We have developed an aptamer affinity column (AAC) for the purification and enrichment of trace aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) in genuine agro-products through the covalent conjugation of amino modified aptamer and NHS-activated Sepharose. The coupling and working conditions found to be suitable for this AFB-AAC were examined in regard to coupling time (2 min), loading volume (30 mL), and the methanol concentration (< 10%) used in the loading step. The performance of AFB-AAC was then further evaluated in terms of capacity (329.1 ± 13.7 ng for AFB1 and 162.5 ± 8.9 ng for AFB2), selectivity (excellent), reusability (twenty-three times for AFB1 and twelve times for AFB2), and repeatability (92.7% ± 2.9% for AFB1 and 71.5% ± 3.4% for AFB2). Furthermore, the AAC clean-up combined with HPLC-FLD demonstrated excellent linearity over a wide range, good sensitivity with an LOD of 50 pg mL-1 for AFB1 and 15 pg mL-1 for AFB2, and acceptable recovery with different spiking levels in different matrices. Finally, the AAC was successfully applied to analyte AFB1 and AFB2 in four types of agro-products as well as a maize flour reference material, and the results were found to be in accordance with those of commercial IACs. This study provides a reference for the analysis of other trace analytes by merely changing the corresponding aptamer and represents a strong contender for immune affinity columns. Graphical abstract An aptamer affinity column for purification and enrichment of aflatoxin B1 and aflatoxin B2 in agro-products with the aid of HPLC-FLD and a post-column photochemical derivatization reactor.


Assuntos
Aflatoxina B1/isolamento & purificação , Aflatoxinas/isolamento & purificação , Aptâmeros de Nucleotídeos/química , Cromatografia de Afinidade/métodos , Aflatoxina B1/análise , Aflatoxinas/análise , Arachis/química , Cromatografia Líquida de Alta Pressão/métodos , Análise de Alimentos/métodos , Limite de Detecção , Oryza/química , Triticum/química , Zea mays/química
2.
J Chromatogr A ; 1609: 460431, 2020 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-31431356

RESUMO

A combined procedure based on using ultrasounds for target isolation followed by porous membrane-protected micro solid phase extraction using a molecularly imprinted polymer as an adsorbent has been developed as a highly selective extraction and clean-up procedure for isolating aflatoxins B1, B2, G1, and G2 from fish feed before ultra-high-performance liquid chromatography tandem mass spectrometry determination. Polymeric adsorbent beads have been synthesized by the precipitation polymerization method which guarantees a homogeneous particles size distribution and the integrity of the generated imprinted cavities. In addition, polymerization was performed using a higher proportion of organic solvent (toluene) in the porogen mixture, which generates MIP particles adequate for interacting with targets dissolved in organic (hydro-organic) mixtures (extracts from fish feed). These approaches led to a selective and high efficient pre-concentration method for AFs. Ultrasound-assisted extraction (10 mL of 60:40 acetonitrile/0.1 M KH2PO4 pH 6.0, 40% amplitude, continuous sonication for 7.0 min) allowed an efficient aflatoxins isolation from fish feed. In addition, the resulting pH of the extract (pH 7.0) has been found to be the optimum for performing clean-up/pre-concentration (enrichment factor of 33.3) by molecularly imprinted polymer based micro-solid phase extraction (orbital horizontal shaking speed at 150 rpm for 10 min for loading, and 5 mL of 95:5 acetonitrile/formic acid as eluting solution using ultrasounds 35 kHz for 15 min). The current proposal was shown to be an accurate and precise method through relative standard deviation of intraday and inter-day tests below 20% and analytical recoveries in the range of 80-100%. The limits of detection were within the 0.42-1.15 µg kg-1 range, quite lower than those established by European Commission guidelines for aflatoxins in animal feeds.


Assuntos
Aflatoxinas/análise , Ração Animal/análise , Cromatografia Líquida de Alta Pressão/métodos , Impressão Molecular , Polímeros/química , Microextração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Ultrassom , Aflatoxinas/química , Animais , Calibragem , Cromatografia Líquida/métodos , Peixes , Concentração de Íons de Hidrogênio , Limite de Detecção , Padrões de Referência
3.
J Sci Food Agric ; 100(3): 1048-1055, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31677164

RESUMO

BACKGROUND: Magnetic three-dimensional graphene-based nanoadsorbents have unique characteristics such as large surface area, good thermal and chemical stability, and high adsorption capacity that make them efficient materials in sorbent-based extraction techniques. In this study, four aflatoxins (AFs) were analyzed in bread samples using magnetic three-dimensional graphene as the adsorbent phase in dispersive micro solid-phase extraction. RESULTS AND CONCLUSIONS: In-syringe magnetic sheet solid-phase extraction based on magnetic three-dimensional graphene in tandem with dispersive liquid-liquid microextraction was used for the extraction and preconcentration of the target AFs. The effect of significant parameters of the method was investigated and the optimum conditions were determined as follows: adsorbent dosage, 20 mg; desorption/disperser solvent (methanol) volume, 700 µL; desorption solvent flow rate, 0.7 mL min-1 ; pH, neutral; salt (NaCl) concentration, 10% (w/v); extraction solvent (chloroform) volume, 250 µL; and centrifugation rate (and time), 4000 rpm (5 min). The limits of detection and quantification were in the ranges 0.043-0.083 and 0.14-0.28 µg kg-1 , respectively. The extraction method was followed by the HPLC technique with fluorescence detection and applied to the determination of the AFs in four different Iranian fresh and moldy bread samples. The relative recoveries were in the range 84-107% with relative standard deviations of 3.9-8.6%. © 2019 Society of Chemical Industry.


Assuntos
Aflatoxinas/isolamento & purificação , Pão/análise , Contaminação de Alimentos/análise , Microextração em Fase Líquida/métodos , Magnetismo/métodos , Extração em Fase Sólida/métodos , Adsorção , Aflatoxinas/análise , Cromatografia Líquida de Alta Pressão , Irã (Geográfico) , Extração em Fase Sólida/instrumentação , Seringas
4.
Int J Food Microbiol ; 313: 108376, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31731141

RESUMO

Maize is an important staple crop for the majority of the population in Uganda. However, in tropical and subtropical climates, maize is frequently contaminated with aflatoxins, a group of cancer-causing and immuno-suppressive mycotoxins produced by Aspergillus section Flavi fungi. In Uganda, there is limited knowledge about the causal agents of aflatoxin contamination. The current study determined both the aflatoxin levels in pre-harvest maize across Uganda and the structures of communities of aflatoxin-producing fungi associated with the maize. A total of 256 pre-harvest maize samples were collected from 23 major maize-growing districts in eight agro-ecological zones (AEZ). Maize aflatoxin content ranged from 0 to 3760 ng/g although only around 5% for Ugandan thresholds. For EU it is about 16% of the samples contained aflatoxin concentrations above tolerance thresholds. A total of 3105 Aspergillus section Flavi isolates were recovered and these were dominated by the A. flavus L morphotype (89.4%). Densities of aflatoxin-producing fungi were negatively correlated with elevation. Farming systems and climatic conditions of the AEZ are thought to have influenced communities' structure composition. Fungi from different AEZ varied significantly in aflatoxin-producing abilities and several atoxigenic genotypes were identified. The extremely high aflatoxin concentrations detected in some of the studied regions indicate that management strategies should be urgently designed for use at the pre-harvest stage. Atoxigenic genotypes detected across Uganda could serve as aflatoxin biocontrol agents to reduce crop contamination from fields conditions and throughout the maize value chain.


Assuntos
Aflatoxinas/análise , Aspergillus/metabolismo , Contaminação de Alimentos/análise , Zea mays/microbiologia , Agricultura , Aspergillus/genética , Aspergillus/isolamento & purificação , Ecologia , Uganda , Zea mays/química , Zea mays/crescimento & desenvolvimento
5.
Food Chem ; 305: 125429, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505415

RESUMO

A simple and rapid magnetic solid-phase extraction (MSPE) method using PEGylated multi-walled carbon nanotubes magnetic nanoparticles (PEG-MWCNTs-MNP) as absorbents is proposed for isolation and enrichment of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2), aflatoxin M1 (AFM1), aflatoxin M2 (AFM2), ochratoxin A (OTA), zearalenone (ZEA), zearalanone (ZAN), α-zeralanol (α-ZAL), ß-zeralanol (ß-ZAL), α-zeralenol (α-ZOL), and ß-zeralenol (ß-ZOL) from liquid milk. Combined with ultra-high performance liquid chromatography Q-Exactive high resolution mass spectrometry, simultaneous qualification of these mycotoxins was achieved with sensitivity and specificity. The proposed method showed a good linearity (R2 ≥ 0.995), high sensitivity (limit of detection in the range of 0.005-0.050 µg/kg and limit of quantification in the range of 0.015-0.150 µg/kg), adequate recovery (81.8-106.4%), and good repeatability (intra-day precision in the range of 2.1-8.5% and inter-day precision in the range of 3.9-11.7%). It has been successfully applied to the determination of 13 mycotoxins in real liquid milk samples.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Leite/química , Micotoxinas/análise , Extração em Fase Sólida/métodos , Aflatoxinas/análise , Animais , Magnetismo , Nanotubos de Carbono , Ocratoxinas/análise , Sensibilidade e Especificidade , Zearalenona/análise
6.
Pak J Pharm Sci ; 32(4): 1679-1686, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31608890

RESUMO

Four fungal isolates were identified in this study of which three were Aspergillus species with Aspergillus flavus having the highest frequency followed by A. parasiticus. The result of high frequency of Aspergillus flavus and Aspergillus parasiticus in the Zea mays sample revealed production of aflatoxins. Maize sample in Awka was found to contain aflatoxin B1 (9.60ppb) and B2 (13.3ppb). Inhibition of A. flavus and A. parasiticus with Azadirachta indica and Garcinia kola seed extracts showed that the test plant extracts were effective for reducing mycelial growth on the test organism. Methanolic extract of G. kola showed antifungal inhibitory activity on the test organisms and the highest at 10% concentration. With ethanol extracts of G. kola, the antifungal activity was effective i.e. for inhibition of A. flavus and A. parasiticus, with A. parasiticus having the higher percentage inhibition at 10%. Inhibiting growth of Aspergillus flavus and Aspergillus parasiticus using methanolic and ethanolic extracts of neem seeds was effective in the inhibition of the test organism at 10%. The methanolic and ethanolic extracts of combined Garcinia kola and neem seeds revealed effective inhibition of A. flavus and A. parasiticus with ethanolic extracts of the combined test plants exerting the highest inhibition against A. flavus (80.43±3.62). The extracts from this plant show the ability to suppress growth of toxigenic A. flavus and A. parasiticus. Phytochemical analysis showed that the methanolic and ethanolic extracts of G. kola and neem seeds showed the presence of secondary metabolites and this may be a reason for the inhibitory activity on A. flavus and A. parasiticus. Results from this study will be important in planning a management strategy against aflatoxin-producing fungi and other fungi associated with spoilage of stored food products.


Assuntos
Aflatoxinas/metabolismo , Antifúngicos/farmacologia , Aspergillus/metabolismo , Azadirachta/química , Garcinia kola/química , Zea mays/microbiologia , Aflatoxinas/análise , Antifúngicos/química , Aspergillus/efeitos dos fármacos , Aspergillus/isolamento & purificação , Aspergillus/patogenicidade , Etanol/química , Microbiologia de Alimentos , Armazenamento de Alimentos , Metanol/química , Testes de Sensibilidade Microbiana , Nigéria , Compostos Fitoquímicos/análise , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Sementes/microbiologia
7.
Anal Chim Acta ; 1088: 79-88, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31623719

RESUMO

In response to the Canadian federal government's Cannabis Tracking and Licensing System compliance standards, a quantitative method was created for cannabis analysis, and validated using Eurachem V.2 (2014) guidelines. Cannabinol, cannabidiol, cannabigerol, cannabichromene, cannabidiolic acid, cannabigerolic acid, Δ-9-tetrahydrocannabinol, and Δ-9-tetrahydrocannabinolic acid A were all analysed by scheduled multiple reaction monitoring (MRM) via LC-MS/MS and isotope dilution. In addition, aflatoxins B1, B2, G1, and G2 were also analysed by scheduled MRM via LC-MS/MS and matrix matched calibration curves in order to achieve the reporting limits (≤2 µg kg-1) set out by the European Pharmacopoeia. The LODs/LOQs were 0.50/1.7, 2.0/6.7, 0.59/2.0, and 0.53/1.8 µg kg-1, for B1, B2, G1, and G2 respectively. Thirty one terpenes were analysed by selected reaction monitoring via GC-MS/MS and isotope dilution using ß-myrcene-d6 as a surrogate. All quantitative analyses can be accomplished using less than 1 g of material, with minimal solvent and consumable use, on low resolution instruments in less than 30 min of instrument time. Of important note is this method's power of selectivity, working ranges, and lack of need for extraction consumables such as SPE or QuEChERS, thereby minimising analytical costs and time.


Assuntos
Aflatoxinas/análise , Canabinoides/análise , Cannabis/química , Contaminação de Medicamentos/prevenção & controle , Regulamentação Governamental , Fidelidade a Diretrizes , Terpenos/análise , Canadá , Cromatografia Líquida , Medição de Risco , Espectrometria de Massas em Tandem
8.
Wei Sheng Yan Jiu ; 48(5): 828-833, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31601329

RESUMO

OBJECTIVE: To analyze the results of international proficiency tests for aflatoxin determination and to identify the requirement of quality assurance and control in mycotoxin analysis. METHODS: By the use of Z-scores, the results of aflatoxins from international proficiency tests were analyzed and the critical control points in experimental operation were discussed. RESULTS: The absolute values of the Z-scores of aflatoxins were less than 2, indicating that the results from the laboratory were satisfactory. The sampling and testing method had very important effects on the detection results. CONCLUSION: The results of the international proficiency tests of aflatoxins suggested that to strengthen the critical control points in the experimental operation can effectively improve the accuracy and reliability of the determination results.


Assuntos
Aflatoxinas/análise , Monitoramento Ambiental/métodos , Contaminação de Alimentos , Laboratórios , Reprodutibilidade dos Testes
9.
Artigo em Inglês | MEDLINE | ID: mdl-31569703

RESUMO

Among the array of structurally and toxicologically diverse mycotoxins, aflatoxins have attracted the most interest of scientific research due to their high toxicity and incidence in foods and feeds. Despite the undeniable progress made in various aspects related to aflatoxins, the ultimate goal consisting of reducing the associated public health risks worldwide is far from being reached due to multiplicity of social, political, economic, geographic, climatic, and development factors. However, a reasonable degree of health protection is attained in industrialized countries owing to their scientific, administrative, and financial capacities allowing them to use high-tech agricultural management systems. Less fortunate situations exist in equatorial and sub-equatorial developing countries mainly practicing traditional agriculture managed by smallholders for subsistence, and where the climate is suitable for mould growth and aflatoxin production. This situation worsens due to climatic change producing conditions increasingly suitable for aflatoxigenic mould growth and toxin production. Accordingly, it is difficult to harmonize the regulatory standards of aflatoxins worldwide, which prevents agri-foods of developing countries from accessing the markets of industrialized countries. To tackle the multi-faceted aflatoxin problem, actions should be taken collectively by the international community involving scientific research, technological and social development, environment protection, awareness promotion, etc. International cooperation should foster technology transfer and exchange of pertinent technical information. This review presents the main historical discoveries leading to our present knowledge on aflatoxins and the challenges that should be addressed presently and in the future at various levels to ensure higher health protection for everybody. In short, it aims to elucidate where we come from and where we should go in terms of aflatoxin research/development.


Assuntos
Aflatoxinas/toxicidade , Pesquisa Biomédica/história , Microbiologia de Alimentos/história , Micotoxicose/história , Venenos/toxicidade , Aflatoxinas/análise , Aflatoxinas/química , Agricultura/história , Agricultura/métodos , Pesquisa Biomédica/métodos , Mudança Climática , Países em Desenvolvimento , Microbiologia de Alimentos/métodos , Saúde Global , Política de Saúde , História do Século XVII , História do Século XIX , História do Século XX , História Antiga , Humanos , Micotoxicose/diagnóstico , Micotoxicose/etiologia , Micotoxicose/terapia , Venenos/análise , Venenos/química , Estudos Prospectivos , Saúde Pública/história , Estudos Retrospectivos
10.
Int J Food Microbiol ; 310: 108307, 2019 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-31476582

RESUMO

Aspergillus section Flavi is widely known as a potential threat to contaminate agricultural products and food commodities. In this study, a polyphasic approach consisting of micro- and macro-morphological, chemical and molecular features, was applied to survey the Aspergillus section Flavi population in corn collected from Guangxi, China. Based on multigene phylogenies as well as morphological observations, Aspergillus flavus (192/195), A. arachidicola (1/195), A. pseudonomius (1/195) and A. novoparasiticus (1/195) were found to be the predominant section Flavi population. Among them, 31 representative isolates were selected for mycotoxin determination. The results showed that Aspergillus flavus chemotype I was most common, chemotype IV was also detected with low incidence and low CPA amounts, while chemotypes II and III were absent. Other tested species including A. arachidicola, A. pseudonomius, and A. novoparasiticus produced all types of aflatoxins, but none of them produced CPA. The polyphasic approach applied in this study permitted reliable understanding of the prevailing Aspergillus section Flavi population and their mycotoxin profiles. Knowledge of the prevailing section Flavi population will aid in developing a sustainable strategy to mitigate the effects of aflatoxin contamination. This study suggests that CPA contamination of food should be considered while conducting mycotoxigenic surveys of food commodities, and the same should be considered while planning a bio-control strategy to control aflatoxin contamination.


Assuntos
Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Zea mays/microbiologia , Aflatoxinas/análise , Aspergillus/genética , Aspergillus/isolamento & purificação , Sequência de Bases , China , Micotoxinas/análise , Filogenia
11.
Artigo em Inglês | MEDLINE | ID: mdl-31499294

RESUMO

The ionic liquid (IL) was introduced to the synthesis system of magnetic zeolite imidazolate framework-8 (M/ZIF-8), which was benefit to the formation of binary imidazole and the co-modification of M/ZIF-8. The morphology and textural properties of ILM/ZIF-8 were characterized by SEM, TEM, BET and BJH. The crystal structural shape and size of MZIF-8 was unvaried with the interventional of IL. The ILM/ZIF-8 was applied to the concentration and determination of aflaoxins (AFB1, AFB2, AFG1 and AFG2) in milk samples based on magnetic solid phase extraction (MSPE) coupled with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The experimental parameters of the MSPE, including amount of ILM/ZIF-8, pH, type and amount of desorption solvent, extraction time and sample volume were investigated by a univariate method and orthogonal screening. The four AFs were concentrated from the 20 mL milk when 90 mg ILM/ZIF-8 was used as magnetic adsorbent. The extraction efficiency of AFs was higher than 80.0% within 15 min. The limits of quantitative and detection were 7.5-26.7 and 2.3-8.1 ng/L, respectively. The proposed method was applied to the determination of milk samples containing trace amounts of AFs and the recoveries ranged from 79.0% to 102.5%, with RSD below 7.7%.


Assuntos
Aflatoxinas/análise , Nanopartículas de Magnetita/química , Leite/química , Extração em Fase Sólida/métodos , Zeolitas/química , Animais , Cromatografia Líquida de Alta Pressão/métodos , Imidazóis/química , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem/métodos
12.
Food Chem Toxicol ; 133: 110729, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31381944

RESUMO

The present study aimed to develop a consortium of nutritive fermented food products, supplemented with phytochemicals, with reduced toxicological contents. We developed new flavored Doenjang products (protein rich) fermented with lotus, ginkgo, and garlic plant extract-based Meju (termed as EMD) as the starter culture and by using traditional Meju (termed as TMD), where these plant extracts were added later during the fermentation process. Fermented Doenjang samples were analyzed for reduced levels of biogenic amines (BAs), aflatoxins, and microbial hazards, (including Bacillus cereus) as well as for their nutritive contents and antioxidant potential, after varying periods of fermentation (0, 3, 6, 9 and 12 months). All Doenjang samples prepared using plant extracts and their mixtures (1% and 10%) showed desired reduction in B. cereus counts, BAs, aflatoxins, and other foodborne pathogens as well as showed potent antioxidant abilities, including phenolic/flavonoid contents. Based on the higher efficiency in reducing various toxicants, Ginkgo biloba leaf extract added TMD samples were selected for the development of Doenjang products as an innovative approach, with great potential to improve the quality and safety of soybean fermented products in the Korean market, offering enhanced health benefits and reduced risks of toxicity.


Assuntos
Aflatoxinas/análise , Carga Bacteriana , Aminas Biogênicas/análise , Extratos Vegetais/análise , Alimentos de Soja/análise , Bacillus cereus/isolamento & purificação , Linhagem Celular , Cor , Fermentação , Microbiologia de Alimentos/métodos , Qualidade dos Alimentos , Depuradores de Radicais Livres/análise , Alho/química , Ginkgo biloba/química , Humanos , Concentração de Íons de Hidrogênio , Coreia (Geográfico) , Lotus/química , Alimentos de Soja/microbiologia , Soja/química , Soja/microbiologia
13.
Artigo em Inglês | MEDLINE | ID: mdl-31314691

RESUMO

Tofu or bean curd is obtained from soybean seeds being a widespread food product in Asia. The commodity used for its production can be contaminated with aflatoxins, which are secondary metabolites synthetised by species of Aspergillus flavus and A. parasiticus. Intake of contaminated food products causes toxic effects on consumers. The aim of this work was to study aflatoxin distribution in fractions obtained from pilot-scale tofu production with contaminated soybeans. The presence of the aflatoxins B1, B2, G1 and G2 (AFs) in soaking water, okara, whey and tofu was analysed. Aflatoxin analysis was performed by HPLC with fluorescence detection. The distribution of aflatoxins in all the analysed fractions was not a normal distribution. The liquid fractions (soaking water and whey) had less contamination than solid fractions (tofu and okara). The percentage AFB1 remaining in nutritionally important fractions, okara and tofu, was between 6.2% and 67.7% (median = 18.1%) and 0.5% and 13.2% (median = 3.5%), respectively. AFB2, AFG1 and AFG2 had a similar distribution. These results showed that throughout tofu production, AFs can be present in the products intended for human consumption.


Assuntos
Aflatoxinas/análise , Contaminação de Alimentos/análise , Alimentos de Soja/análise , Aspergillus/química , Humanos
14.
Zhongguo Zhong Yao Za Zhi ; 44(10): 2009-2014, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31355553

RESUMO

Ziziphi Spinosae Semen is one of the Chinese herbal medicine being susceptible to aflatoxins contamination. To investigate the sources of aflatoxins contamination and toxigenic fungi species on Ziziphi Spinosae Semen,32 samples were collected from multiple steps during the post-harvest processing in this study. Aflatoxins in these samples were determined by immunoaffinity column and HPLC coupled with post-column photochemical derivatization. The dilution-plate method was applied to the fungi isolation. The isolated fungi strains were identified by morphological characterization and molecular approaches. The results showed that aflatoxins were detected in 28 samples from every step during the processing of Ziziphi Spinosae Semen. Three samples were detected with aflatoxin B_1 and 2 samples with both aflatoxin B_1 and total aflatoxin exceeding the limit of Chinese Pharmacopoeia. Especially the samples from the washing step,with the highest detected amounts of AFB_1 and AFs were reached 94. 79,121. 43 µg·kg~(-1),respectively. All 32 samples were contaminated by fungi. The fungal counts on the newly harvested samples were 2. 20 × 10~2 CFU·g~(-1). Moreover,it increased as tphreocessing progresses,and achieved 1. 16×10~6 CFU·g~(-1) after washing. A total of 321 isolates were identified to 17 genera. Aspergillus flavus was the main source of aflatoxins during the processing and storage of Ziziphi Spinosae Semen. One isolate of A. flavus was confirmed producing AFB_1 and AFB_2. The fungal count was significantly increased by composting,and Aspergillus was the predominant genus after shell breaking. The contamination level of aflatoxins was increased by composting and washing.


Assuntos
Aflatoxinas/análise , Fungos/isolamento & purificação , Sementes/química , Sementes/microbiologia , Ziziphus/química , Aspergillus , Cromatografia Líquida de Alta Pressão
15.
Anal Chim Acta ; 1078: 142-150, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358212

RESUMO

Mycotoxins and pesticides are prevalent in cereal food. It is difficult to detect these two kinds of hazard factors simultaneously in rapid assay. In order to find a solution to the problem, carbamates and aflatoxins were selected in this study to establish a rapid, on-site, and quantitative paper sensor. Two novel monoclonal antibodies (mAbs) against carbaryl and carbofuran (1D2 and G11) were developed. The IC50 values (half maximal inhibitory concentration) were 0.8 ng/mL and 217.6 ng/mL for carbaryl and carbofuran, respectively. Based on the sensitive and specific mAbs, a multi-TRFICA (time-resolved fluorescence) paper sensor was developed, which simultaneously detected six types of hazardous chemicals, including AFB1, AFB2, AFG1, AFG2, carbaryl, and carbofuran. A universal sample pretreatment method for mycotoxins and pesticides was explored to apply on established competitive indirect enzyme-linked immunosorbent assay (icELISA) and multi-TRFICA-paper sensor. The established paper sensor can be easily observed with naked eyes, qualitatively under a UV lamp, and quantitated using a home-made device. It exhibited a calculated limit of quantity for AFTs, carbaryl, and carbofuran of 0.03, 0.02, and 60.2 ng/mL in corn samples, respectively. The spiking-recoveries and real sample studies proved that multi-TRFICA-paper sensor is an accurate, sensitive, and high throughput detection method for simple and low-cost analysis in corn samples.


Assuntos
Aflatoxinas/análise , Ensaio de Imunoadsorção Enzimática/métodos , Papel , Resíduos de Praguicidas/análise , Anticorpos Monoclonais/imunologia , Carbaril/imunologia , Carbofurano/imunologia , Európio/química , Fluorescência , Contaminação de Alimentos/análise , Nanopartículas Metálicas/química , Zea mays/química
16.
Food Chem ; 293: 472-478, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31151636

RESUMO

Water activity (aw) and temperature are two pivotal environmental factors affecting Aspergillus flavus growth and aflatoxin production. Here, we found that AFB1 production on polished rice can occur over a wider range of temperature × aw levels than that on paddies. For fungal growth on polished rice, the optimum conditions were aw 0.92-0.96 and 28-37 °C. The maximum amounts of AFB1 on polished rice was observed at 33 °C and aw 0.96. Compared to 33 °C, all tested genes of A. flavus on polished rice were significantly up-regulated at 25 °C under aw 0.96. The late structural genes of pathway were significantly down-regulated at 37 °C under aw 0.96, although aflR and aflS and most of early structural genes were up-regulated. Compared to aw 0.96, most of pathway genes were significantly down-regulated at aw 0.90 and 0.99 under 33 °C, although two regulatory genes were up-regulated at aw 0.90.


Assuntos
Aflatoxinas/biossíntese , Aspergillus flavus/metabolismo , Aflatoxinas/análise , Aspergillus flavus/genética , Aspergillus flavus/crescimento & desenvolvimento , Cromatografia Líquida de Alta Pressão , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Oryza/microbiologia , Temperatura , Água/química , Água/metabolismo
17.
Food Chem ; 297: 124912, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253263

RESUMO

An anti-idiotypic nanobody-phage display-mediated immuno-polymerase chain reaction (PD-IPCR) method was developed for simultaneous quantitative detection of total aflatoxins and zearalenone in cereals. Two phages, displaying the variable domain of the heavy chain anti-idiotypic nanobody that binds aflatoxin- or zearalenone-specific monoclonal antibody (1C11 or 2D3), were used as competitors for corresponding analytes. Specific DNA sequences encoding anti-idiotypic nanobodies were used to design the primers for PCR amplification. The results indicated that detection limits for total aflatoxins and zearalenone in a sample were 0.03 and 0.09 ng mL-1, respectively. Recoveries of spiked aflatoxins and zearalenone were 80-118% and 76.7-111%, respectively. Validation results were in good agreement with the gold-standard high-performance liquid chromatography method. This report is the first to describe PD-IPCR for simultaneous quantitative detection of total aflatoxins and zearalenone in cereals.


Assuntos
Aflatoxinas/análise , Anticorpos Anti-Idiotípicos/imunologia , Imunoensaio/métodos , Zearalenona/análise , Aflatoxinas/imunologia , Anticorpos Anti-Idiotípicos/genética , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Oryza/química , Oryza/metabolismo , Biblioteca de Peptídeos , Reação em Cadeia da Polimerase em Tempo Real/métodos , Anticorpos de Domínio Único/genética , Anticorpos de Domínio Único/imunologia , Zea mays/química , Zea mays/metabolismo , Zearalenona/imunologia
18.
Food Chem Toxicol ; 129: 458-465, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31085221

RESUMO

Aflatoxin and fumonisin are two major foodborne mycotoxins: toxic chemicals produced by fungi that contaminate food commodities including maize, a staple food in sub-Saharan Africa. Aflatoxin causes liver cancer, and is associated with acute liver toxicity and immunotoxicity; while fumonisin is associated with neural tube defects in infants and esophageal cancer. Both mycotoxins have been associated with child growth impairment. Previous studies suggest that co-occurrence of these mycotoxins may have potentially synergistic toxicological effects. Despite health risks associated with co-occurrence of these mycotoxins, no study has examined their co-occurrence along key food supply chains in Africa. This study is the first report that examines the occurrence and co-occurrence of aflatoxins and fumonisins along the maize value chain in Nigeria. All samples were analyzed using LC-MS/MS. About 52% and 21% of the samples had aflatoxin levels above the Nigerian and US standards for human food, respectively. Though no regulatory limits exist for fumonisin in Nigeria, 13% of the samples contained fumonisin levels higher than the US regulatory limit. Aflatoxin levels can become dangerously high in maize stored four months or longer. Adequately addressing mycotoxin risk requires consideration of the entire maize value chain and associated value chains for food production.


Assuntos
Aflatoxinas/análise , Cadeia Alimentar , Fumonisinas/análise , Zea mays/química , Animais , Contaminação de Alimentos/análise , Humanos , Nigéria
19.
Food Chem Toxicol ; 128: 171-179, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30965105

RESUMO

In order to understand the changes in toxic metabolite profiles in uncooked and cooked foods, samples of flour/grain (n = 40) and their corresponding plate-ready food (n = 39) were collected from 40 households in two states of northern Nigeria. The food samples were analyzed for multiple fungal metabolites by LC-MS/MS and daily intakes of mycotoxins in the diets were estimated and compared to established margin of exposure (MOE) and tolerable daily intake (TDI) values. Both food groups contained 65 fungal and plant metabolites, inclusive of 23 mycotoxins. The mean concentrations of aflatoxin B1, beauvericin, fumonisin B1 (FB1), FB2, FB3, hydrolysed FB1, moniliformin and nivalenol were significantly (p < 0.05) higher in flour than in the plate-ready food samples. The levels of several mycotoxins were higher in the flour samples than in plate-ready meals by 129-383%. The dilution effect from proportionate mixing of flour samples with water led to 48-100% reduction in detectable mycotoxins in flour to plate-ready meals. Aflatoxins and fumonisins co-occurred in 36% of the plate-ready foods. Exposures of households to aflatoxins and fumonisins based on 95% CI concentration of mycotoxins in the meals were high, suggesting potential health risks based on calculated low MOE and exceedence of stipulated TDI value, respectively.


Assuntos
Culinária , Características da Família , Contaminação de Alimentos/análise , Micotoxinas/análise , Venenos/análise , Saúde da População Rural , Adolescente , Adulto , Aflatoxinas/análise , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Cromatografia Líquida , Exposição Dietética , Feminino , Fumonisinas/análise , Humanos , Lactente , Limite de Detecção , Masculino , Pessoa de Meia-Idade , Nigéria , Espectrometria de Massas em Tandem , Adulto Jovem
20.
Pak J Biol Sci ; 22(3): 133-142, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30972983

RESUMO

BACKGROUND AND OBJECTIVE: Incorporation of food byproducts in biscuit could increase the safety, nutritional and enhance dough properties. These byproducts were wheat bran (WB), goldenberry fruit (GBF) and goldenberry peel (GBP) contains active ingredients. MATERIAL AND METHODS: Wheat flour (WF) was partially replaced in biscuit dough. Antioxidant activity, chemical composition and baking quality were evaluated. Anti-aflatoxigenic and antifungal activities of WB, GBF and GBP have estimated also aflatoxin reduction was evaluated. RESULTS: The results were showed biscuit acceptable sensories. The GBF and GBP exhibited the highest antioxidant and phenolic content explaining its antimicrobial behaviour. The addition of WB, GBF or GBP to fungal media inhibited the growth, however, using 20% GBF in Aspergillus flavus media showed the greatest aflatoxin reduction. The biscuit-specific volume was more pronounced when GBF and GBP were included in the formulation. No great differences were seen for colour, baking quality or texture of biscuit mixes. CONCLUSION: This novel safe biscuit appears a safer alternative to traditional biscuits.


Assuntos
Aflatoxinas/análise , Contaminação de Alimentos/prevenção & controle , Tecnologia de Alimentos , Physalis/química , Aspergillus flavus/química , Aspergillus niger/efeitos dos fármacos , Fibras na Dieta , Escherichia coli/efeitos dos fármacos , Farinha , Inocuidade dos Alimentos , Frutas/química , Fusarium/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Penicillium chrysogenum/efeitos dos fármacos , Salmonella typhi/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Triticum
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA