RESUMO
In this study, 135 samples of cocoa beans collected in the Amazon and Atlantic Forest regions of Brazil were analysed to evaluate the possible co-occurrence of 34 mycotoxins. The results indicate that 42% of the cocoa samples exhibited quantifiable levels for 11 mycotoxins: aflatoxins (AFs) B1, B2 and G1; ochratoxin A; citrinin; cyclopiazonic acid; tenuazonic acid; paxilline; sterigmatocystin; zearalenone and fumonisin B2. Of the samples, 18% exhibited the co-occurrence of up to six mycotoxins. No toxins belonging to the groups of trichothecenes or ergot alkaloids were detected. Contingency analysis of the incidence of mycotoxins did not show significant differences between the two regions evaluated. Seven samples were contaminated with AFs, while only one contained ochratoxin A above 10 µg kg-1. The accuracy of the method was evaluated by proficiency testing for ochratoxin A, where satisfactory Z-scores were obtained.
Assuntos
Micotoxinas , Tricotecenos , Micotoxinas/análise , Cromatografia Líquida/métodos , Espectrometria de Massas em Tandem/métodos , Brasil , Tricotecenos/análise , Esterigmatocistina/análise , Contaminação de Alimentos/análise , Aflatoxina B1/análiseRESUMO
The levels of aflatoxins B1, B2, G1, and G2, ochratoxin A, zearalenone and sterigmatocystin were determined by thin-layer chromatography in 36 samples of stored maize in the state of Rio Grande do Sul; the samples were obtained from May to September 1988, 23 samples were from silos and 13 samples were collected directly from farms. In 34.8% of the samples from silos aflatoxin B1+G1 was detected in concentrations that varied from 12 to 906 micrograms/kg. In 13% of the samples from silos aflatoxin B2 was detected in concentrations that varied from 48 to 180 micrograms/kg. In 9% of the samples from silos aflatoxin G2 was detected in concentrations that varied from 6 to 11 micrograms/kg. In 23% of the samples collected directly from farms aflatoxin B1+G1 was detected in concentrations that varied from 10 to 14 micrograms/kg. Ochratoxin A, zearalenone and sterigmatocystin were not detected at any time.
Assuntos
Contaminação de Alimentos , Micotoxinas/análise , Zea mays/química , Aflatoxina B1/análise , Aflatoxinas/análise , Brasil , Ocratoxinas/análise , Esterigmatocistina/análise , Zearalenona/análiseRESUMO
Wheat from two cultivars with contrasting characteristics were harvested in ten experimental plots located in wheat producing areas of the State of São Paulo, Brazil. The samples (10 of each cultivar) were analyzed by a gas-chromatographic method for deoxynivalenol (DON), nivalenol (NIV), diacetoxyscirpenol (DAS), toxins T-2 (T-2) and HT-2, T-2 tetraol, T-2 triol, and by a thin-layer chromatographic method for zearalenone (ZEN), aflatoxins B1, B2, G1, G2, ochratoxin A and sterigmatocystin. No mycotoxins were detected in 13 samples. DON was found in four samples (0.47-0.59 microgram/g), NIV in three samples (0.16-0.40 microgram/g), T-2 in two samples (0.40, 0.80 microgram/g), DAS in one sample (0.60 microgram/g), and ZEN in three samples (0.04-0.21 microgram/g). The wheat samples were also examined for the incidence of fungi. Alternaria, Drechslera, Epicoccum and Cladosporium were the prevailing genera. Among the Fusarium spp., F. semitectum was present in 19 samples and F. moniliforme in 18 samples. No F. graminearum was isolated in the samples.
Assuntos
Contaminação de Alimentos , Fungos/isolamento & purificação , Micotoxinas/análise , Triticum/química , Triticum/microbiologia , Aflatoxinas/análise , Brasil , Carcinógenos Ambientais/análise , Cromatografia , Fungos/classificação , Ocratoxinas/análise , Esterigmatocistina/análise , Tricotecenos/análise , Zearalenona/análiseRESUMO
A previously published method for ochratoxin A was evaluated and proved appropriate for simultaneous determination of aflatoxins, ochratoxin A, sterigmatocystin, and zearalenone, with considerable savings in time and reagent costs. The detection limits were 2, 5, 15, and 55 micrograms/kg, respectively. The recoveries and coefficients of variation obtained with artificially contaminated samples were 91-101% and 0-16% for aflatoxin B1, 98-117% and 0-17% for sterigmatocystin, and 96-107% and 0-17% for zearalenone, respectively. The coefficients of variation for naturally contaminated samples (aflatoxins in rice and ochratoxin A in beans) ranged from 0 to 8%. The method was used to survey 296 samples that included 10 cultivars of dried beans, 8 types of corn products, 3 types of cassava flour, and both polished and parboiled rice between May 1985 and June 1986 in Campinas, Brazil. Only aflatoxin B1 (9 samples, 20-52 micrograms/kg), aflatoxin G1 (4 samples, 18-31 micrograms/kg), and ochratoxin A (5 samples, 32-160 micrograms/kg) were found. The average contamination percentage was 4.7%; beans showed the highest (6.6%) and rice showed the lowest (3.3%) incidence rates. Zearalenone and sterigmatocystin were not detected. Positive samples were confirmed by chemical derivatization, corroborated by development in 3 solvent systems.