The current AOAC International methods for the determination of fumonisins have been validated for corn and cornflakes but have produced low recoveries and high variability when applied to processed corn products for infants. Hence, an investigation was undertaken to improve the extraction efficiency for fumonisins by investigating the use of different extraction solvents. Corn-based infant foods containing cornmeal, corn starch, and corn flour were purchased in the city of Campinas, state of Sao Paulo, Brazil, and were analyzed for fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) following extraction with a range of solvents. Comparison of the results from each of the samples indicated that acidified 70% aqueous methanol at pH 4.0 provided the best overall performance, whereas a methanol/boric acid (pH 9.2) mixture displayed poor extraction efficiency. Extraction with acidified 70% aqueous methanol showed seven of eight test samples to be positive for FB1 (range, 30 to 6,127 microg/kg; relative SD, 4.2 to 51.7%), two of eight samples to be positive for FB2 (range, 53 to 1,738 microg/kg; relative SD, 4.5 to 5.3%), and one of eight samples to be positive for FB3 (575 microg/kg). For samples in which extraction with phosphate-buffered mixtures (pH 3) proved superior, the method suffered from poor chromatography due to interfering compounds. The findings indicate that matrix interferences play a significant role in the extractability, cleanup, and chromatography of the fumonisins.

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O objetivo desse trabalho foi verificar a viabilidade do uso de aparelho de microondas para a determinação do teor de umidade de grãos de milho. Nesse estudo foram utilizadas amostras de milho com teor de umidade na faixa de 7,33 a 22,28%. Equações de regressão linear foram determinadas correlacionando-se os valores de percentagem de água retirada após secagem no microondas e o teor de umidade determinado pelo método de estufa a 105oC ± 3o C por 24 horas. O tempo de permanência do produto no aparelho de microondas foi fixado em 45 segundos. Nas condições em que o experimento foi realizado, o aparelho de microondas mostrou ser uma alternativa viável para a determinação de umidade de grãos de milho.
The possibility of using a micro-wave oven as a rapid method for moisture determination of corn grain was verified, as well as the effects of different potencies on the moisture content of the grains. In this study corn samples with moisture contents in the range of 7,33 to 22,28% were used. Linear regression lines were determined by the relation of the values of percentage of water taken out after drying in the microwave and the moisture contents determinated by the oven official method (105°± 3°C/24 hours). The drying time of the product was fixed at 45seconds. In the conditions of this experiment, the microwave oven has shown to be a feasible alternative for a rapid determination of the corn moisture content

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A survey of 196 samples of corn-based infant foods from 13 cities of Sao Paulo State, Brazil, was carried out to investigate the fumonisin contamination in the products. Based on their ingredients, the products were divided into seven groups: infant cereal designated as types A-D, corn meal, corn starch and instant cereal baby food. Although certain infant food samples were free of fumonisin contamination (<20 microg kg(-1); corn starch and infant cereals of type A, B and D), contamination levels in the other products (corn meal, instant corn-based baby food and cereal type C) were of concern, particularly those in corn meal. All samples in these categories contained fumonisins. The mean level for total fumonisins (FB1 + FB2 + FB3) in corn meal was 2242 microg kg(-1) (maximum 8039 microg kg(-1)), in instant corn-based baby food was 437 (maximum 1096) microg kg(-1) and in infant cereal type C was 664 (maximum 1753) microg kg(-1).

The relationships between fungal growth and ergosterol content and between aflatoxins B1 and B2 production and ergosterol content were verified in corn grains. In the first experiment, fungal growth and ergosterol content were monitored during incubation of corn grains presenting water activities of 0.85aw and 0.92aw at 25ºC over a period of 18 days. For the Taiúba variety, the fungi growth and ergosterol content increased more rapidly for 0.92aw than 0.85aw. Maximum ergosterol levels were 2.8 and 4.6 µg/g, respectively, for 0.85aw and 0.92aw. For the Cargill hybrid 606, a more pronounced increase in fungal growth was verified just at the end of the incubation period, mainly for 0.92aw when an acentuated increase in ergosterol content was also observed. Maximum ergosterol levels detected were 1.6 µg/g and 5.8 µg/g, respectively, for 0.85aw and 0.92aw. There was a significant correlation between ergosterol content and log of CFU g -1 for 0.92aw but not for 0.85 aw. In the second experiment, samples of corn grains of the Taiúba variety at 0.87aw and 0.95aw were inoculated with a toxigenic Aspergillus flavus strain and incubated at 25ºC. Ergosterol levels reached maximum values of 12.1 and 73.4 µg/g, respectively, for 0.87aw and 0.95aw. In both water activities, content aflatoxin B1 followed the same trend as ergosterol. For the aflatoxin B2 this trend was not observed. Ergosterol assay appears to be a useful test to measure fungal growth and to indicate the possibility of aflatoxin production in corn grains.

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