Ciênc. Tecnol. Aliment., Campinas, 24(1): 079-083, jan.-mar. 2004 71 Distribution of aflatoxin contamination in maize samples, Gloria et al. 1. Recebido para publicação em 25/09/2003. Aceito para publicação em 14/11/2003 (000986). 2. Universidade de São Paulo – ESALQ, CEP-13418-900, Piracicaba-SP. Brasil. Fax: (55) (19) 422-5678. E-mail: emgloria@carpa.ciagri.usp.br 3. Universidade Estadual de Campinas – FEA, Campinas-SP. Brasil. 4. Universidade Paulista – IBILCE, São José do Rio Preto-SP, Brasil. 5. Vega Armazéns Gerais, Mogi-Guaçu-SP, Brasil. *A quem a correspondência deve ser enviada. 1 – INTRODUCTION The aflatoxin contamination in Brazilian maize was previously reported by FONSECA et al. [4, 5], SOARES & RODRIGUEZ-AMAYA [14], and GLORIA [6]. While official rules for qualitatively characterizing maize lots have been used in Brazil since 1976 [2], there is no information in the literature about the distribution of aflatoxin contamination among different samples fractions considered in Brazilian maize grading rules. Despite this, it is common for Brazilian maize users to consider, for any maize lot, specific maize fractions considered in the rules, such as fermented and sprouted grains, foreign materials as well as broken grains and impurities as the major source responsible for detected aflatoxin levels. The literature documents that the distribution of aflatoxin contamination on agricultural products, including maize, is extremely heterogeneous [7, 8, 12]. Studies conducted by SHOTWELL, GOULDEN & HESSELTINE [10, 11] on the distribution of aflatoxin contamination among maize fractions showed that the distribution was variable for each maize lot and there was no assurance that high contamination levels were due to the amount of a specific maize fraction present in the lot. The main objective of this work was to study the distribution of aflatoxin contamination among maize fractions separated from samples according to the grain fraction defined by the official Brazilian maize grading rules. The contribution of each fraction to the total aflatoxin contamination level in the maize samples was also evaluated. 2 – MATERIAL AND METHODS 2.1 – Samples The samples for this study were chosen from those collected on a routine basis by the raw material quality control service of the Brazilian maize processing industry. From samples collected over the study period, 22 samples were employed for the tests. According to the industry quality control, 19 samples were classified as contaminated. The determination and separation of contaminated and non-contaminated samples were done initially by DISTRIBUTION OF AFLATOXIN CONTAMINATION IN MAIZE SAMPLES 1 Eduardo Micotti da GLORIA 2, *, César Francisco CIACCO 3 , José Francisco LOPES FILHO 4 , Cynthia ERICSSON 5 , Silvio Sandoval ZOCCHI 2 RESUMO DISTRIBUIÇÃO DA CONTAMINAÇÃO COM AFLATOXINAS EM AMOSTRAS DE MILHO. A distribuição da contaminação com aflatoxinas foi estudada entre quatro frações separadas de acordo com as regras brasileiras de classificação do milho. A fração que continha grãos ardidos, mofados, queimados e brotados normalmente tinha os níveis mais altos de aflatoxina. Contudo, a contribuição da fração para a contaminação da amostra inteira levou em conta o nível de contaminação da fração e seu peso na amostra inteira. Considerando isto, a fração que continha os grãos danificados por insetos, chochos, fermentados até ¼ e injuriados por outras causas, foi normalmente a maior responsável pelo nível de contaminação total das amostras. Apesar disto, as contribuições das frações foram variáveis de amostra para amostra. Portanto, foi concluído que não foi possível estabelecer um comportamento padrão para contribuição das frações de grãos para diferentes lotes de milho. A classificação brasileira por tipos aplicada nas amostras não mostrou correlação estatística com os níveis de contaminação com aflatoxinas (P<0,05). Duas amostras classificadas com o melhor tipo qualitativo (tipo 1) apresentaram contamina- ção de 380 e 146ng/g. O número de amostras com nível de contaminação acima daquele permitido pela lei brasileira (20ng/g) foi o mesmo para os tipos qualitativos 2, 3 e AP (Abaixo do Padrão). Palavras-chave: aflatoxina; contaminação; distribuição; tipo de grão; milho. SUMMARY 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). Keywords: aflatoxin; contamination; distribution; grain type; maize.