Guilherme Prado

Effect of gamma irradiation on the inactivation of aflatoxin B1 and fungal flora in peanut

The effect of gamma irradiation on aflatoxin B1 levels and fungal infection were investigated in peanut samples, Tatu Vermelho cultivar. At a radiation dose of 10 KGy, growth of molds was completely inhibited. Doses of 15, 20, 25 and 30 KGy were sufficient for destruction of aflatoxin B1 by 55-74%. The results suggested that the decontamination of molds by irradiation, before production of aflatoxin B1, is the most acceptable method in the preservation of peanut.

Incidence of ochratoxin A in roast and ground coffee and soluble coffee consumed in the City of Belo Horizonte, MG.

The occurrence of ochratoxin A was measured in soluble coffee samples and roast and ground coffee, market in Belo Horizonte / MG, between october/1998 and may / 1999. The method used for determining ochratoxin A was high performance liquid chromatography combined with immunoaffinity chromatography. Recoveries and coefficients of variation of ochratoxin A demonstrated levels above 73% and lower than 15%, respectively. Samples of soluble coffee and roast and ground coffee contained ochratoxin A at levels between 0,31 and 1,78ng/g and 0,99 and 5,87ng/g, respectively. The results showed that the contamination levels found in the coffee were not significant.

Detection of ochratoxin A in tropical wine and grape juice from Brazil

BACKGROUND Ochratoxin A (OTA) is the main mycotoxin found in grapes, wines and grape juices and is considered one of the most harmful contaminants to human health. In this study, samples of tropical wines and grape juices from different grape varieties grown in Brazil were analysed for their OTA content by high-performance liquid chromatography. RESULTS The detection and quantification limits for OTA were 0.01 and 0.03 µg L(-1) respectively. OTA was detected in 13 (38.24%) of the samples analysed, with concentrations ranging from < 0.03 to 0.62 µg L(-1). OTA was not detected in any of the grape juice samples. Most of the red wine samples proved to be contaminated with OTA (75%), while only one white wine sample was contaminated. However, the OTA levels detected in all samples were well below the maximum tolerable limit (2 µg L(-1)) in wine and grape juice established by the European Community and Brazilian legislature. CONCLUSION The results of this study indicate a low risk of exposure to OTA by consumption of tropical wines and grape juices from Brazil.

Ocorrência de aflatoxina M1 em leite consumido na cidade de Belo Horizonte - Minas Gerais / Brasil - agosto/98 à abril/99

Sixty one samples of fluid and powder milk from Belo Horizonte / Minas Gerais - Brasil, period of August 98/April 99, were examined for aflatoxin M1. The quantification was done by high performance liquid chromatography using an immunoaffinity column for cleanup. The limit of quantification (LOQ) was 6 ng/L. Average recoveries and coefficients of variation were higher than 88,9% and lower than 22,4%, respectively. AFM1 was found in 50 (82%) of the analyzed samples, but at levels lower than 500 ng/L, which is the maximum limit permitted in Brazil.

Ochratoxigenic fungi associated with green coffee beans (Coffea arabica L.) in conventional and organic cultivation in Brazil.

The genera Aspergillus comprises species that produce mycotoxins such as aflatoxins, ochratoxins and patulin. These are cosmopolitan species, natural contaminants of agricultural products. In coffee grains, the most important Aspergillus species in terms of the risk of presenting mycotoxins belong to the genera Aspergillus Section Circumdati and Section Nigri. The purpose of this study was to assess the occurrence of isolated ochratoxigenic fungi of coffee grains from organic and conventional cultivation from the South of Minas Gerais, Brazil, as well as to evaluate which farming system presents higher contamination risk by ochratoxin A (OTA) produced by fungi. Thirty samples of coffee grains (Coffea arabica L.) were analysed, being 20 of them of conventional coffee grains and 10 of them organic. The microbiological analysis was done with the Direct Plating Technique in a Dichloran Rose Bengal Chloramphenicol Agar (DRBC) media. The identification was done based on the macro and micro morphological characteristics and on the toxigenic potential with the Plug Agar technique. From the 30 samples analysed, 480 filamentous fungi of the genera Aspergillus of the Circumdati and Nigri Sections were isolated. The ochratoxigenic species identified were: Aspergillus auricoumus, A. ochraceus, A. ostianus, A. niger and A. niger Aggregate. The most frequent species which produces ochratoxin A among the isolated ones was A. ochraceus, corresponding to 89.55%. There was no significant difference regarding the presence of ochratoxigenic A. ochreceus between the conventional and organic cultivation systems, which suggests that the contamination risk is similar for both cultivation systems.

Reduction of aflatoxin B1 in stored peanuts (Arachis hypogaea L.) using Saccharomyces cerevisiae.

Aflatoxin B(1) is a toxigenic and carcinogenic compound produced by Aspergillus flavus and Aspergillus parasiticus. To inhibit aflatoxin contamination of peanuts, seeds of two peanut breeds, IAC Caiapó and IAC Runner 886, were inoculated with A. parasiticus (1.0 × 10(6) spores per ml) and the yeast Saccharomyces cerevisiae (3.2 × 10(7) cells per ml) and incubated at 25°C for 7 and 15 days. Two experiments were conducted for each incubation period separately. The treatments were completely randomized, with three replications per treatment. Treatments included the two cultivars and three types of inoculation (pathogen alone, yeast and pathogen, and yeast 3 h before pathogen). Aflatoxin B(1) was quantified with a densitometer at 366 nm after thin layer chromatography. Aflatoxin B(1) contamination in peanuts was reduced after the addition of S. cerevisiae. The concentration of aflatoxin B(1) decreased by 74.4 and 55.9% after 7 and 15 days, respectively. The greatest aflatoxin reduction was observed when S. cerevisiae was inoculated 3 h before the pathogen in IAC Caiapó seeds and incubated for 7 days at 25°C. The use of S. cerevisiae is a promising strategy for biological control of aflatoxin contamination in peanuts.

Aflatoxinas em alimentos destinados a bovinos e em amostras de leite da região de Lavras, Minas Gerais - Brasil

A aflatoxina M1 (AFM1) tem sido detectada em leite de animais alimentados com racao contaminada por aflatoxina B1 (AFB1), possuindo efeitos toxicos e carcinogenicos muito proximos. Constitui-se um problema de Saude Publica, pois sua toxidez e preocupante, quando os individuos mais jovens estao entre os maiores consumidores de leite e estes sao os mais sensiveis a seus efeitos. O objetivo deste trabalho foi determinar a presenca de aflatoxinas em alimentos destinados a bovinos e de AFM1 em amostras de leite cru e apos pasteurizacao. Trabalhou-se inicialmente com 12 produtores de leite, permanecendo apenas 2 produtores que apresentavam valores significativos de aflatoxina M1. A coleta de leite foi realizada 24 h apos a coleta do alimento. O metodo utilizado para a deteccao de aflatoxinas no alimento foi a cromatografia em camada delgada. A determinacao de AFM1 em leite foi realizada empregando-se coluna de imunoafinidade para a purificacao e deteccao por cromatografia liquida de alta eficiencia em fase reversa. Nao foram detectadas aflatoxinas nas amostras de racao. Entretanto, detectou-se AFM1 em 19 (52,8%) das 36 amostras de leite cru, em valores que variaram de tracos a 74,1 ng L-1. Em leite pasteurizado, a AFM1 foi detectada em 13 (38,2%) das 34 amostras, em niveis que variaram desde tracos a 58,9 ng L-1. Os valores encontrados de aflatoxina no leite estao dentro dos padroes tolerados pela legislacao brasileira. As concentracoes de aflatoxina nos leites cru e pasteurizado nao diferiram entre si (p>0,05). O fato de nao se ter detectado aflatoxinas na racao pode ser explicado pela sua ocorrencia em baixas concentracoes, isto e, inferiores ao limite de deteccao do metodo utilizado (2 mg/Kg), o que nao impediria o aparecimento da AFM1 no leite e a deteccao mediante metodologia mais sensivel (2 ng/L).

Efeito da irradiação (60Co) na frequência fúngica de amendoim in natura em função do tempo de prateleira

Foi verificado o efeito da irradiacao gama (60Co) na capacidade de destruir a microbiota fungica, em amendoim em grao, cultivar Tatu Vermelho, da safra 2003 (segundo semestre). Os graos de amendoim, apos a irradiacao, foram mantidos a temperatura ambiente em embalagem plastica comercial, durante 180 dias. Para a determinacao da porcentagem fungica foi utilizada a tecnica do plaqueamento direto utilizando o meio Agar Dicloran Rosa de Bengala Cloranfenicol (DRBC), desinfetando ou nao os graos com solucao de hipoclorito de sodio. Em graos de amendoim irradiados e desinfetados externamente, observou-se reducao da infeccao fungica a 5 kGy e destruicao total de fungos a 10 kGy, apos 180 dias de armazenamento a temperatura ambiente. Em graos irradiados e nao desinfetados externamente foram verificados, em funcao do tempo de armazenamento, aumento da populacao de fungos com a dose de 1 kGy, reducao com a dose de 5 kGy e eliminacao total com a aplicacao de 10 kGy. A irradiacao gama, na dose de 10 kGy ou superior, demonstrou ser um processo eficaz na reducao da microbiota fungica de amendoim em grao, cultivar Tatu Vermelho.

Occurrence of aflatoxin B1 in natural products

The media claims for the consumption of natural resource-based food have gradually increased in both developing and developed countries. The interest in the safety of these products is partially due to the possible presence of toxigenic fungi acting as mycotoxin producers, such as aflatoxins produced during the secondary metabolism of Aspergillus flavus, A. parasiticus and A. nomius. Aflatoxins, mainly aflatoxin B1, are directly associated with liver cancer in human beings. This paper is aimed at evaluating the presence of aflatoxin B1 in a few vegetable drugs, dried plant extracts and industrialized products traded in 2010 in the city of Belo Horizonte, State of Minas Gerais, Brazil. The method used for the quantification of aflatoxin B1 was based on extraction through acetone:water (85:15), immunoaffinity column purification followed by separation and detection in high efficiency liquid chromatography. Under the conditions of analysis, the Limits of Detection and Quantification were 0.6 µg kg-1 and 1.0 µg kg-1respectively. The complete sets of analyses were carried out in duplicate. Aflatoxin B1 was noticed in a single sample (< 1.0 µg kg-1). The results revealed low aflatoxin B1contamination in the products under analysis. However, it is required to establish a broad monitoring program in order to obtain additional data and check up on the actual extension of contamination.

Incidencia de fungos toxigênicos e aflatoxinas em arroz

Um dos problemas mais serios que confrontam a qualidade do arroz e a presenca de fungos produtores de micotoxinas, principalmente as especies pertencentes aos generos Aspergillus, Penicillium e Fusarium. Neste estudo, objetivou-se verificar os niveis de aflatoxinas e identificar a populacao fungica associada a graos de arroz beneficiado e comercializado em Belo Horizonte e algumas cidades do sul do estado. Foram analisadas um total de 60 amostras de arroz: orgânico, parboilizado, integral, polido, sendo a incidencia de aflatoxinas verificada em uma amostra. Os resultados demonstraram que as especies aflatoxigenicas identificadas foram A. parasiticus e A. flavus. Utilizando Cromatografia Liquida de Alta Eficiencia para avaliar a incidencia de aflatoxina em arroz, apenas uma apresentou contaminacao de 1,2 ig Kg-1. Apesar da presenca de fungos aflatoxigenicos, as amostras nao apresentaram niveis preocupantes de aflatoxinas que pudessem colocar em risco a seguranca do produto e a saude dos consumidores.