Eduardo Micotti da Gloria

Antimicrobial activity of yerba mate (Ilex paraguariensis St. Hil.) against food pathogens

Yerba mate (Ilex paraguariensis St. Hil.) has been studied for its important biological activities mainly attributed to phenolic compounds. This study evaluated the antimicrobial activity of methanolic and ethanolic extracts of yerba mate against food pathogens, such as Staphylococcus aureus, Listeria monocytogenes, Salmonella Enteritidis and Escherichia coli through minimum inhibitory (MIC) and bactericidal (MBC) concentrations, in addition to the determination of chemical composition by gas chromatography with mass spectrometry (GC-MS) and phenolic content. The most effective extract had its activity evaluated under different pH conditions by growth curve analysis. All microorganisms except E. coli were inhibited. The ethanolic extract showed the lowest MIC/MBC (0.78/0.78 mg/ml), the highest phenolic content (193.9 g.GAE/kg) and the presence of chlorogenic acid derivatives, especially 3-O-caffeoylquinic and caffeic acid. This extract was able to inhibit microbial growth at pH 7 and 8.

Co-occurrence and distribution of deoxynivalenol, nivalenol and zearalenone in wheat from Brazil

ABSTRACT Fusarium mycotoxins deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) were investigated in wheat from the 2009 and 2010 crop years. Samples (n = 745) from commercial fields were collected in four wheat producing regions (WPR) which differed in weather conditions. Analyses were performed using HPLC-DAD. Contamination with ZEN, DON and NIV occurred in 56, 86 and 50%, respectively. Also, mean concentrations were different: DON = 1046 µg kg−1, NIV < 100 µg kg−1 and ZEN = 82 µg kg−1. Co-occurrence of ZEN, DON and NIV was observed in 74% of the samples from 2009 and in 12% from 2010. Wet/cold region WPR I had the highest mycotoxin concentration. Wet/moderately hot region WPR II had the lowest mycotoxin levels. Furthermore, the mean concentration of each mycotoxin was higher in samples from 2009 as compared with those from 2010. Precipitation during flowering or harvest periods may explain these results.

Formas termolisada e viva de leveduras na redução de toxicidade causada por aflatoxinas

As aflatoxinas sao metabolitos hepatotoxicos produzidos por algumas linhagens de Aspergillus flavus, A. parasiticus e, eventualmente, por A. nomius sobre grande numero de produtos agricolas. Esta pesquisa foi conduzida para avaliar a capacidade de Saccharomyces cerevisiae, nas formas termolisada e desidratada viva, em reduzir os danos causados por aflatoxinas. Para tal, foi preparada uma dieta basica e desta se obtiveram quatro formulacoes: uma como controle; as demais contaminadas com aflatoxinas na concentracao de 400 mg kg-1, sendo duas com posterior adicao de 1% de leveduras, uma na forma termolisada e outra como desidratada viva. Um bioensaio com duracao de 28 dias foi efetuado com ratos Wistar. Foram realizados os estudos do peso relativo de orgaos internos e a analise do tecido hepatico dos animais. Os pesos relativos de orgaos internos de animais submetidos aos diferentes tratamentos nao diferiram estatisticamente entre si; o tecido do figado dos animais submetidos a dieta livre de aflatoxinas foi adotado como padrao de isento de toxidez; o tecido hepatico dos animais que receberam dieta controle com aflatoxinas apresentaram sinais claros de toxicidade; os animais que receberam dieta com aflatoxinas + 1% de levedura termolisada apresentaram sinais de toxicidade semelhantes ao controle com aflatoxinas; o tecido hepatico dos animais que receberam dieta com aflatoxinas + 1% de levedura viva apresentaram sinais de toxicidade menores do que os animais que receberam a dieta controle com aflatoxinas. As leveduras termolisadas nao foram capazes de suprimir os efeitos das aflatoxinas; as leveduras vivas apresentaram habilidade de reduzir os efeitos promovidos por aflatoxinas.

Distribution of aflatoxins in corn fractions visually segregated for defects

The aflatoxin distribution in corn fractions obtained after visual segregation for defects in 30 samples, known to be contaminated, was studied. Each sample was passed through a 5.0 mm round holes sieve, graded for defects and then segregated in sound kernels (regular kernels) and non-sound kernels (injured, germinated, fermented, moldy, heated, insect damaged, immature, broken, hollow, fermented up to ¼, discolored, extraneous materials, and injured by other causes), as defined by the Brazilian Official Grading rules for corn. The non-sound kernels showed the highest contamination levels in all samples. The contamination levels of non-sound kernels (20% of total weight) ranged from 23 to 1,365 µg/kg of aflatoxins (B1, B2, G1 and G2) and were higher than sound kernels (p<1%) ranging from not detected (ND) to 126 µg/kg and in 87% of these the aflatoxin contents were lower than 20 µg/kg. Statistically significant correlation indexes were found among the percentage of defective groups like fermented, heated and sprouted kernels or the total injured kernels, and the estimated contamination levels for the sound and non sound fractions. It was concluded that the non-sound kernels fraction, even being small in weight, has contributed with 84% of the estimated contamination of the samples. The segregation of the non-sound kernels would favor a reduction in the contamination of corn lots. The poorer quality corn types (types 3 and Bellow Standart) have predominated among samples of the experiment.

Aflatoxin M1 in raw milk from different regions of São Paulo state – Brazil

A total of 635 raw milk samples from 45 dairy farms, from three regions of São Paulo state – Brazil, were evaluated during 15 months for aflatoxin M1 (AFM1). AFM1 was determined by high performance liquid chromatograph with fluorescence detection. AFM1 was detected (>0.003 µg kg−1) in 72.9%, 56.3% and 27.5% of the samples from Bauru, Araçatuba and Vale do Paraíba regions, respectively. The mean AFM1 contamination considering all the samples was 0.021 µg kg−1. Furthermore, the concentration of AFM1 was quite different among Bauru (0.038 µg kg−1), Araçatuba (0.017 µg kg−1) and Vale do Paraíba (<0.01 µg kg−1) regions. Only three samples (0.5%) had higher contamination than the tolerated limit in Brazil (0.50 µg kg−1) and 64 samples (10.1%) had a higher contamination than the maximum limit as set by the European Union (0.050 µg kg−1). The estimated AFM1 daily intake was 0.358 and 0.120 ng kg−1 body weight per day for children and adults, respectively.

Evaluation of the black light test for screening aflatoxin-contaminated maize in the Brazilian food industry

The results of the black light test for aflatoxin-contaminated maize carried out in a large food factory in the State of São Paulo was evaluated against bi-directional thin layer chromatography (TLC) analysis for 286 samples of maize. All 286 samples were accepted by the black light test (< 7 fluorescent points), however, the results from TLC analysis showed that 96 samples were contaminated and 14 showed aflatoxin B1 contamination levels higher than 20 micrograms/kg. There were 14 false negative results and no false positives and out of the 14 samples, six did not show visible fluorescent points. If the rejection criterion of one or more fluorescent points were applied, the six samples would be accepted by the black light test. But, in this case, 95 samples would be rejected and 87 results would be false positives because they did not have contamination levels over 20 micrograms/kg which is the acceptance limit of the black light test. The results indicate that the black light test, as utilized by this factory, was not able to indicate lots with possible contamination and the black light test, as recommended in the literature, would produce a high number of false positives. It is necessary to make more studies on the use of black light as a screening test for possible aflatoxin B1-contaminated maize.

Distribution of aflatoxin contamination in maize samples

The distribution of the aflatoxin contamination was studied among four maize fractions, separated according to Brazilian grading rules for maize. The fraction that contained fermented, moldy, heated and sprouted grains normally had the highest levels of aflatoxin. However, the fraction contribution to the whole sample contamination level took into account the contamination fraction level and its weight to the whole sample. Considering this, the fraction that contained insect damaged, hollow, up to ¼ fermented and grains damaged by other causes was normally the fraction responsible for the total contamination level in the samples. Nevertheless, the fraction contributions were variable from sample to sample. Therefore, in conclusion, it was not possible to establish a standard behavior for grain fraction-type contribution for different maize lots. The Brazilian grading by qualitative types applied to samples did not show statistic correlation with aflatoxin contamination levels (P<0.05). Two type-1 samples (the best quality type) presented contamination of 380 and 146ng/g. The number of samples with contamination levels above those allowed by Brazilian law (20ng/g) was the same for qualitative types 2, 3, and BS (Below Standard).

SELEÇÃO ELETRÔNICA PELA COR NA DESCONTAMINAÇÃO DE AMENDOIM CONTAMINADO COM AFLATOXINAS

Quarenta e dois lotes comerciais de 300 kg de amendoim descascado, produzidos em 1997 e contaminados com aflatoxinas, foram submetidos a selecao eletronica pela cor para verificar a eficiencia desse processo na melhoria da qualidade de lotes de amendoim quanto a diminuicao da contaminacao com aflatoxinas. Os lotes de amendoim foram classificados pelo tamanho como normalmente utilizados pela cerealista, sendo 22 lotes de amendoim graudo (7,5 a 7,9mm) e 20 lotes de amendoim miudo (6,4 a 7,1mm), nos quais os niveis de contaminacao inicial variaram de 7 a 3.763 mg/kg e de 76 a 3.309 mg/kg, respectivamente. Nos 42 lotes, nao foram detectadas aflatoxinas em dois lotes de amendoim graudo e 1 de amendoim miudo. Este trabalho demonstrou que o processo de selecao eletronica retirou graos altamente contaminados, concentrando-os na porcao rejeito. Apesar disso, nao houve uma melhora substancial nos niveis iniciais medios de contaminacao dos lotes indicando que a distribuicao das aflatoxinas estava generalizada, uma vez que, os graos selecionados tambem estavam contaminados. Em lotes com menor contaminacao pode funcionar. Novos estudos serao realizados.

Distribution of aflatoxins in contaminated corn fractions segregated by size

The efficiency of segregation, by particle size, in reducing the aflatoxin content of corn lots under the Brazilian conditions was studied. The aflatoxin content, in the corn fractions obtained after sieving thirty contaminated samples, with approximately 3.0 kg each, was determined. The samples were passed through 4.5 mm round-hole sieves and the fractions with particles ³4.5 mm (fraction A) and <4.5 mm (fraction B) and then analyzed for aflatoxins by TLC. The results showed that the distribution of the aflatoxins among the fractions A and B varied from sample to sample. However, the fraction B presented higher content (6 to 1,422 µg/kg) of aflatoxins (P<5%), than samples of fraction A (4 to 389 µg/kg). In spite of that the segregation of this fraction did not reduce significantly the contamination of the samples. This probably occurred because the contribution of the fraction B for the estimated total of the concentration of aflatoxin of the sample was smaller than that of the fraction A, due to the smallest amount of the fraction B in the sample weight total. In spite of being significant for the studied samples the correlation among the percentages of the groups of grains with defects a) burning grains, sprouted, burned and moldy and b) total injured, with the estimated level of contamination for the samples, more studies will be necessary so that better conclusions can be drawn for this correlation.

Post-harvest control of aflatoxin production in in-shell moist peanuts with sodium ortho-phenylphenate: III. Storage tests

O presente trabalho teve por objetivo avaliar a eficiencia da solucao de ortofenilfenato de sodio (OFS), no controle da producao de aflatoxinas quando aplicada no amendoim em casca, umido. Trabalhos anteriormente realizados, em condicoes de campo, indicaram a necessidade de otimizar a aplicacao da solucao, para se poder avaliar a real eficiencia dessa substância. Assim, neste experimento, o sistema de pulverizacao foi adaptado na bica de saida da maquina de pre-limpeza, no armazem. Na safra das aguas de 1989, dois lotes de 120 sacos de amendoim em casca umido foram pulverizados com solucao de OFS em concentracoes de 0,5 e 1,0 % e verificou-se que nao houve controle da producao de aflatoxinas em ambas as concentracoes utilizadas. Nas safras da seca de 1989 e das aguas de 1990 o amendoim em casca umido foi pulverizado com solucao de OFS na concentracao de 5,0%. A cobertura das vagens com a solucao foi eficiente, permitindo uma distribuicao uniforme da solucao de OFS sobre as vagens. Os resultados obtidos mostraram que nenhuma das concentracoes utilizadas controlou a producao de aflatoxinas, quando aplicadas no amendoim em casca, embora, aparentemente, tenham controlado o crescimento fungico da parte externa das vagens de amendoim. Provavelmente os fungos aflatoxigenicos ja poderiam estar presentes dentro de vagens sadias e desse modo a casca do amendoim poderia ser uma barreira a penetracao do fungicida dentro da vagem e atingir as amendoas.