Contaminação de aflatoxinas em castanha-do-brasil com casca em sistemas extrativista e de plantio.

Diante de problemas de contaminação por aflatoxinas enfrentados na cadeia produtiva da castanha-do-brasil, o objetivo deste trabalho foi estudar o teor de aflatoxinas em castanhas com casca em diferentes etapas dos sistemas de produção: extrativista e de plantio. A produção extrativista consiste na coleta de ouriços recém caídos das árvores e permanecidos no solo por vários dias, empilhamento na floresta, abertura e seleção de castanhas com casca, seguida de armazenamento/secagem sob ventilação durante vários meses. Contudo, no sistema de plantio somente os ouriços com menos de 5 dias no solo são coletados, em seguida são desinfectados com hipoclorito de sódio a 1% e armazenados sob ventilação até abertura e seleção das castanhas com casca. Sessenta amostras de castanha-do-brasil com casca foram coletadas diretamente ou após abertura dos ouriços na região amazônica do Brasil, provenientes da produção extrativista no Acre e do sistema de plantio no Amazonas. As aflatoxinas (B1, B2, G1, G2) foram determinadas por Cromatografia Líquida de Alto Desempenho com detector de fluorescência bem como a atividade de água (aw) nas castanhas descascadas. Nas etapas do sistema extrativista na floresta, dos 33 ouriços coletados, castanhas provenientes de um ouriço com menos de 5 dias de contato com o solo e um ouriço empilhado durante 15 dias apresentaram contaminação por AFB1 inferior a 0,1 µg/kg de matéria fresca (MF). Entretanto o nível de AFB1 variou de 0,6 a 4,4 µg/kg de MF em 3 ouriços com mais de 30 dias em contato com o solo, mais susceptíveis a serem danificados e degradados por condições climáticas e predadores da floresta amazônica. No sistema de plantio, dos 5 ouriços coletados, somente uma amostra proveniente de um ouriço com menos de 5 dias de contato com o solo apresentou contaminação por AFB1, inferior a 0,1 µg/kg de MF. Em armazém ventilado do sistema de plantio, AFB1 foi detectada com teor inferior a 0,1 µg/kg de MF em uma amostra dos 10 ouriços coletados. Todavia no sistema extrativista, os teores de aflatoxinas das castanhas com casca aumentaram e foram superiores ao regulamento europeu (10 µg/kg de MF, UE n°165/2010) ao longo do armazenamento (até 90 dias). A secagem sob ventilação durante o armazenamento não é suficientemente eficaz para atingir rapidamente uma aw inferior a 0,7, evitando o desenvolvimento de fungos aflatoxinogênicos e a produção de aflatoxinas. Resultados sugerem o ouriço como uma barreira de proteção contra estes fungos além de confirmar os estudos anteriores do projeto Safenut que indicam a etapa de secagem sob ventilação e armazenamento das castanhas com casca durante meses no sistema extrativista como etapa crítica na contaminação por aflatoxinas. Portanto, no sistema de plantio, a coleta e o armazenamento após desinfecção com hipoclorito de sódio somente dos ouriços recém caídos das árvores, mesmo por um período de dois meses, permitem evitar a contaminação das castanhas por aflatoxinas

Évaluation des pratiques post récolte favorables à la contamination de l’arachide par les mycotoxines dans trois régions de Côte d’Ivoire

Objectif: Les techniques post récoltes jouent un rôle déterminant dans la contamination de l’arachide par les aflatoxines. Cette étude a pour objectif de contribuer à réduire la contamination de l’arachide par les aflatoxines en Côte d’Ivoire par l’identification des pratiques post récoltes à risque.Méthodologie et résultats: Un questionnaire a permis de recueillir les renseignements sur lesdites pratiques dans trois régions : nord, centre et ouest. Le séchage de l’arachide se fait au soleil quel que soit la localité et dure en moyenne 4 à 14 jours. Les arachides sont séchées et conservées en coques dans le nord. Dans les zones de centre et ouest, les gousses sont soit séchées puis décortiquées, soit décortiqués avant séchage. Le stockage des graines ou des gousses se fait dans des sacs en polyéthylène dans les maisons (86%) ou en vrac dans des greniers (14%). La récolte peut être conservée jusqu’à 9 mois avant consommation ou vente. 58,1% des productrices ont des pertes dues à l’effet des moisissures. La contamination fongique de l’arachide s’opère dans 55,8 % des cas, durant le séchage et le stockage, et dans 34,9 % des cas au cours de l’apparitiondes fleurs au champ.Conclusion et application des résultats: Les étapes de séchage et de stockage représentent un risque de contamination par les aflatoxines. Une maitrise des techniques post récolte permettrait de réduire la contamination par les aflatoxines. Il ressort de cette étude qu'une formation des productrices aux bonnes pratiques de production réduirait la contamination parcours aflatoxines.Mots clés: post-récolte, séchage, conservation, arachide, aflatoxinesEnglish Title: Evaluation of post-harvest practices favorable to the contamination of peanut by mycotoxins in three regions of Côte d'IvoireEnglish AbstractObjective: Post harvest techniques take a decisive role in peanuts by aflatoxins contamination. The aim of this study is to help to reduce aflatoxin contamination of groundnuts in Côte d'Ivoire by identifying post-harvest practices at risk.Methodology and results: A survey permit to collect information on post-harvest practices in three regions: north, center and west. Peanuts are dried at sun whatever the locality and lasts on average 4 to 14 days. Peanuts are dried and kept in pods in the north. In the central and western areas, pods are either dried and then shelled, or shelled before drying. The storage of seeds or pods is done in polythene bags in homes (86%) or bulk in granaries (14%). Peanuts can be kept until 9 months before consumption or sale. 58.1% of producers have losses due to effect of molds. Fungal contamination of peanuts occurs in 55.8% of cases, during drying and storage, and in 34.9% of cases during flowering in the field.Conclusion and application of results: Drying and storage stages represent a risk of contamination by aflatoxins. Mastering post-harvest techniques would reduce aflatoxin contamination. This study shows that training producers in good production practices would reduce aflatoxin contamination.Keywords: post-harvest, drying, storage, peanut, aflatoxin

Comparative diffusion assay to assess efficacy of topical antimicrobial agents against Pseudomonas aeruginosa in burns care

<p>Abstract</p> <p>Background</p> <p>Severely burned patients may develop life-threatening nosocomial infections due to <it>Pseudomonas aeruginosa</it>, which can exhibit a high-level of resistance to antimicrobial drugs and has a propensity to cause nosocomial outbreaks. Antiseptic and topical antimicrobial compounds constitute major resources for burns care but in vitro testing of their activity is not performed in practice.</p> <p>Results</p> <p>In our burn unit, a <it>P. aeruginosa </it>clone multiresistant to antibiotics colonized or infected 26 patients over a 2-year period. This resident clone was characterized by PCR based on ERIC sequences. We investigated the susceptibility of the resident clone to silver sulphadiazine and to the main topical antimicrobial agents currently used in the burn unit. We proposed an optimized diffusion assay used for comparative analysis of <it>P. aeruginosa </it>strains. The resident clone displayed lower susceptibility to silver sulphadiazine and cerium silver sulphadiazine than strains unrelated to the resident clone in the unit or unrelated to the burn unit.</p> <p>Conclusions</p> <p>The diffusion assay developed herein detects differences in behaviour against antimicrobials between tested strains and a reference population. The method could be proposed for use in semi-routine practice of medical microbiology.</p

Evaluation of an alternative spectroscopic approach for aflatoxin analysis: Comparative analysis of food and feed samples with UPLC-MS/MS

Increasing research has highlighted the effects of changing climates on the occurrence and prevalence of toxigenic Aspergillus species producing aflatoxins. There is concern of the toxicological effects to human health and animal productivity following acute and chronic exposure that may affect the future ability to provide safe and sufficient food globally. Considerable research has focused on the detection of these toxins, based on the physicochemical and biochemical properties of the aflatoxin compounds, in agricultural products for human and animal consumption. As improvements in food security continue more regulations for acceptable levels of aflatoxins have arisen globally; the most stringent in Europe. These regulations are important for developing countries as aflatoxin occurrence is high significantly effecting international trade and the economy. In developed countries analytical approaches have become highly sophisticated, capable of attaining results with high precision and accuracy, suitable for regulatory laboratories. Regrettably, many countries that are affected by aflatoxin contamination do not have resources for high tech HPLC and MS instrumentation and require more affordable, yet robust equally accurate alternatives that may be used by producers, processors and traders in emerging economies. It is especially important that those companies wishing to exploit the opportunities offered by lucrative but highly regulated markets in the developed world, have access to analytical methods that will ensure that their exports meet their customers quality and safety requirements. This work evaluates the ToxiMet system as an alternative approach to UPLC–MS/MS for the detection and determination of aflatoxins relative to current European regulatory standards. Four commodities: rice grain, maize cracked and flour, peanut paste and dried distillers grains were analysed for natural aflatoxin contamination. For B1 and total aflatoxins determination the qualitative correlation, above or below the regulatory limit, was good for all commodities with the exception of the dried distillers grain samples for B1 for which no calibration existed. For B1 the quantitative R2 correlations were 0.92, 0.92, 0.88 (<250 μg/kg) and 0.7 for rice, maize, peanuts and dried distillers grain samples respectively whereas for total aflatoxins the quantitative correlation was 0.92, 0.94, 0.88 and 0.91. The ToxiMet system could be used as an alternative for aflatoxin analysis for current legislation but some consideration should be given to aflatoxin M1 regulatory levels for these commodities considering the high levels detected in this study especially for maize and peanuts. (Résumé d'auteur

Potential of lactic acid bacteria for the reduction of fumonisin exposure in African fermented maize based foods

Maize, which contributes to a large portion of the African diet and serves as the base substrate for many fermented cereal products, has been reported to be contaminated with fumonisins. This study aimed to evaluate the in vitro ability of predominant lactic acid bacteria (LAB) in African traditional fermented maize based foods (ogi and mahewu) to bind fumonisin B1 (FB1) and B2 (FB2), as well as the stability of the complex at different pH and temperatures, in particular observed during ogi fermentation and under its storage conditions (time, temperature). The percentage of bound fumonisins was calculated after analysing the level of fumonisins not bound to LAB after a certain incubation time, by HPLC. The results revealed the ability of all tested LAB strains to bind both fumonisins, with binding efficiencies varying between strains and higher for FB2. Binding of fumonisins increased with a decrease in pH from 6 to 4 (observed during the ogi fermentation process) and from 4 to 2 (acidic pH in the stomach), and an increase in temperature (from 30 to 37 °C). The percentage of FB1 and FB2 bound to LAB at pH 4 decreased after 6 days of storage at 30 °C for all LAB strains, except for Lactobacillus plantarum (R1096) for which it increased. Lactobacillus species (L. plantarum and Lactobacillus delbrueckii) were the most efficient in binding FB1 and FB2, whereas Pediococcus sp. was less efficient. Therefore, the Lactobacillus strains tested in this study can be recommended as potential starter cultures for African traditional fermented maize based foods having detoxifying and probiotic properties.The European Union (FP7 245–025) called African Food Revisited by Research (AFTER - http://www.afterfp7.eu/) and a French-South African PHC Protea project (Project N° 29769VL).http://www.wageningenacademic.com/loi/wmjhj2018Food Scienc

Visualisation and quantification of fumonisins bound by lactic acid bacteria isolates from traditional African maize-based fermented cereals, ogi and mahewu

Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (carcinogen; oesophageal cancer in Eastern Cape in South Africa). Lactic acid bacteria (LAB) have emerged as a promising natural detoxification agent against mycotoxins. The aim of this study was to visualise the interaction between fumonisins (FB1 and FB2) and LAB: Lactobacillus plantarum FS2, L. delbrueckii subsp. delbrueckii CIP 57.8T and Pediococcus pentosaceus D39, isolated from traditional fermented maize-based products (ogi and mahewu) using confocal laser scanning microscopy (CLSM) and to then quantify the LAB-bound fumonisin using high performance liquid chromatography (HPLC). The objective was to obtain a physically visible and quantifiable binding interaction between fumonisins and LAB strains with the aim of utilising LAB as a possible detoxifying agent. Fumonisins were derivatised using naphthalene-2,3-dicarboxaldehyde (NDA) and then combined with non-fluorescent LAB cells (viable and non-viable). For the quantification of bound fumonisins, viable and non-viable cells were incubated in the presence of predetermined concentrations of fumonisins and the level of fumonisin in the suspension was determined. CLSM showed the derivatised green fluorescent fumonisins binding to the surface of each of the LAB cells. For viable cells, L. plantarum FS2 bound FB1 most effectively while P. pentosaceus D39 bound the least level of FB1. The highest levels of FB2 were bound by L. plantarum R 1096 and the least by L. delbrueckii CIP 57.8 T. For non-viable cells, L. plantarum FS2 was also the most effective for binding both fumonisins with P. pentosaceus D39 and L. delbrueckii CIP 57.8 T being the least effective for FB1 and FB2, respectively. To our knowledge, this is the first study to visualise the interaction between LAB and fumonisins. We demonstrate that LAB isolates from indigenous fermented maize-based beverages bind fumonisins and thus present a potential strategy for their reduction in these traditional foods.This publication is resulting from a research project funded by the European Union (FP7 245-025) called African Food Revisited by Research (AFTER – http://www.afterfp7.eu/) and from a French-South African PHC Protea project (Project N° 29769VL).http://www.tandfonline.com/loi/tfac202020-01-24hj2019BiochemistryConsumer ScienceFood ScienceGeneticsMicrobiology and Plant Patholog

Visualisation and quantification of fumonisins bound by lactic acid bacteria isolates from traditional African maize-based fermented cereals, ogi and mahewu

Consumption of fumonisin-contaminated foods has a negative influence on the health of humans (carcinogen; oesophageal cancer in Eastern Cape in South Africa). Lactic acid bacteria (LAB) have emerged as a promising natural detoxification agent against mycotoxins. The aim of this study was to visualise the interaction between fumonisins (FB1 and FB2) and LAB: Lactobacillus plantarum FS2, L. delbrueckii subsp. delbrueckii CIP 57.8T and Pediococcus pentosaceus D39, isolated from traditional fermented maize-based products (ogi and mahewu) using confocal laser scanning microscopy (CLSM) and to then quantify the LAB-bound fumonisin using high performance liquid chromatography (HPLC). The objective was to obtain a physically visible and quantifiable binding interaction between fumonisins and LAB strains with the aim of utilising LAB as a possible detoxifying agent. Fumonisins were derivatised using naphthalene-2,3-dicarboxaldehyde (NDA) and then combined with non-fluorescent LAB cells (viable and non-viable). For the quantification of bound fumonisins, viable and non-viable cells were incubated in the presence of predetermined concentrations of fumonisins and the level of fumonisin in the suspension was determined. CLSM showed the derivatised green fluorescent fumonisins binding to the surface of each of the LAB cells. For viable cells, L. plantarum FS2 bound FB1 most effectively while P. pentosaceus D39 bound the least level of FB1. The highest levels of FB2 were bound by L. plantarum R 1096 and the least by L. delbrueckii CIP 57.8 T. For non-viable cells, L. plantarum FS2 was also the most effective for binding both fumonisins with P. pentosaceus D39 and L. delbrueckii CIP 57.8 T being the least effective for FB1 and FB2, respectively. To our knowledge, this is the first study to visualise the interaction between LAB and fumonisins. We demonstrate that LAB isolates from indigenous fermented maize-based beverages bind fumonisins and thus present a potential strategy for their reduction in these traditional foods.This publication is resulting from a research project funded by the European Union (FP7 245-025) called African Food Revisited by Research (AFTER – http://www.afterfp7.eu/) and from a French-South African PHC Protea project (Project N° 29769VL).http://www.tandfonline.com/loi/tfac202020-01-24hj2019BiochemistryConsumer ScienceFood ScienceGeneticsMicrobiology and Plant Patholog