A influência dos ácidos cítrico, acético e oxálico na extração da sílica a partir da casca do arroz foi estudada. As condições experimentais da extração, como pressão e concentração ácida, também foram estudadas. De acordo com o tamanho dos poros pela adsorção de N2, conforme método BET, foram classificadas como mesoporosa. Comparações entre diferentes tipos de ácidos utilizados foram realizadas pela área de superfície específica da sílica obtida.O ácido que apresentou melhor desempenho foi o acético, resultando em área de superfície específica 271 m²/g; o ácido cítrico apresentou o melhor resultado de pureza, 99,96%.

In this work the influence of citric, acetic and oxalic acids on the extraction of nanometric silica from rice hull was studied. The experimental conditions of extraction, such as pressure and acid concentration, were also studied. According to the pore size evaluated by N2 adsorption (BET method), the specimens were classified as mesoporous. Comparisons between different types of acids used were performed by evaluation of the specific surface area of the silica obtained. Acetic acid showed the best performance, resulting in silica with a specific surface area of 271 m²/g. Citric acid showed the best result in terms of purity, 99.96%.

The optimization of the thin layer chromatography (TLC) method to determine aflatoxins in feedstuffs and the evaluation of their occurrence in feedstuffs for milk-yielding does in the state of Bahia were studied. Eighty feedstuff samples were collected from five farms, located in the Recôncavo Baiano, from November 2000 to August 2002. The samples were analyzed using TLC modified method. In this study, the detection and quantification limits were 5 and 8m g/kg, respectively. The percentage of average recoveries obtained for AFB1, AFB2, AFG1, and AFG2 were 81.0; 97.2; 89.3; and 90.3%, respectively; and the coefficient of variation ranged from 0.83 to 4.1%. The results revealed that the optimization of TLC methodology is efficient to analyze aflatoxins in feedstuffs. The presence of these aflatoxins was not detected in any of the analyzed samples, demonstrating good quality of those products, regarding the contamination by these toxins.

Triploid trout has been considered to be more resistant than diploid trout to many diseases and to some adverse aquaculture conditions. Considering the common problems with animal food contamination by aflatoxins, the purpose of this research was to compare the incidence of liver lesions and growth performance in triploid and diploid trout (O. mykiss) exposed to chronic contamination with aflatoxin B1. A total of 240 samples formed 4 groups, diploid and triploid control without aflatoxin in food and diploid and triploid treated with 80 ppb of aflatoxin/Kg of food. Five samples in each group were monthly sacrificed during one year. After the measurement of body weight and length, hepatic samples were obtained and fixed in 10% formalin-saline solution. The histopathological analyses were performed with liver slides stained with hematoxylin and eosin. The comparative analyses of the growth performance showed significant difference between control and treated diploid, suggesting that aflatoxin B1 affects the growing of diploid trout. In triploid groups this aspect was not observed. The histopathological analyses indicated that triploid trout is more resistant to aflatoxin B1, since this group did not present neoplastic lesions. Diploid fishes however, showed 4 samples with neoplastic lesion. The triploid treated group had preneoplastic lesion, but with minor incidence and slower progression than diploid trout

El propósito del presente estudio fue comparar el crecimiento y la incidencia de lesiones hepáticas en truchas triploides y diploides tratadas con aflatoxina B1(AFB1). 240 truchas fueron divididas en 4 grupos: DC: truchas diploides alimentadas con ración sin AFB1; TC: truchas triploides alimentadas con ración sin AFB1; DT: truchas tratadas con ración con 80 ppb de AFB1 y TT: truchas triploides alimentadas con ración con 80 ppb de AFB1. Durante doce meses, mensualmente, cinco ejemplares de cada grupo fueron anestesiados y sacrificados. Con posteiroridad a la obtención del peso y medición del tamaño de los pesces, muestras hepáticas fueron fijadas en solución de formalina salina 10% y procesadas para análisis histopatológico. El análisis comparativo del rendimiento en crecimiento indicaron diferencias significativas entre truchas diploides del grupo control y del tratado, sugiriendo que AFB1 afecta el crecimiento de las truchas diploides. En truchas triploides no se observaron diferencias entre pesces del grupo control y los pesces tratados. El análisis histopatológico señaló que truchas triploides son más resistentes a AFB1, ya que ambos grupos tratados presentaron lesiones preneoplásicas, sin embargo, el grupo TT demostró menor incidencia de lesiones e igualmente un desarrollo más lento de las mismas. En cuanto a la ocurrencia de neoplasia, en el grupo DT 4 pesces desarrolaron carcinoma hepatocelular en el último trimestre del experimento, mientras que ningún animal triploide desarrolló lesión neoplásica

A maçã (Malus domestica Borkhausen) é uma excelente fonte nutricional e de interesse econômico, sendo que a Região Sul do Brasil contribue com 90% da produção Nacional deste fruto com destaque aos cultivares Gala e Fuji. O objetivo deste estudo foi avaliar a produção de patulina nestes cultivares inoculados com Penicillium expansum NRRL 1172 e Penicillium variabile toxigênico, isolado de maçãs regionais. As frutas contaminadas foram mantidas em condições de tempo de armazenamento e temperatura que variaram respectivamente de 15 a 90 dias e de 0 a 25°C. A produção de patulina ocorreu em todas as combinações de armazenagem e temperaturas empregadas para o ensaio, independentemente dos cultivares. A produção de patulina foi negativa no 30º dia nas maçãs estocadas a 0°C inoculadas com P.expansum, mas o aumento de temperatura para 4°C restringiu a margem de segurança, causando positividade na produção da toxina para ambos os cultivares inoculados com as duas linhagens fúngicas, no mesmo período. Nas maçãs inoculadas com P. variabile ocorreu maior concentração de patulina (F=68,05) do que as contaminadas com P. expansum NRRL 1172 (F=26,0). O risco freqüente de produção de patulina nas temperaturas de refrigeração, indicaram a necessidade de melhor controle nos estágios de colheita e armazenagem de maçãs, a fim de evitar constante ingestão de toxina.

The apple (Malus domestica Borkhausen) is an excellent nutritional source of economical interest, with emphasis to the Brazilian Southern Region which comprises 90% of national apple production, mainly Gala and Fuji cultivars.The aim of this research was to evaluate patulin production in both cultivars, inoculated with Penicillium expansum NRRL 1172 and a toxigenic P. variabile strain isolated from commercialized apples. Samples for analysis were taken from apples stored under combined conditions of time and temperature, which ranged from 15 to 90 days period and 0 to 25°C, respectively. Patulin was produced throughout the storage temperatures assayed with both Penicillium strains. The patulin production was negative until 30th day in apples stored at 0°C, but increase of temperature to 4°C restricted the safety threshold. P. variabile produced higher concentration of patulin in inoculated apples (F=68,05) more than P. expansum NRRL1172 (F=26,0). The frequent occurrence of patulin even at refrigerated temperature indicated the importance of quality control at harvest and storage stage of fruits, to avoid constant risk of toxin ingestion.

Foi avaliada a eficiência de dois kits ELISA disponíveis no mercado para detecção de aflatoxina B1, que permitem a triagem de milho contaminado com aflatoxina B1 aos níveis de 5 e 20 ppb. Eles foram comparados ao método de Soares & Rodriguez-Amaya que utiliza cromatografia em camada delgada (CCD) e tem como limite de quantificação 4,0μg/kg (ppb). Foram analisadas 53 amostras incluindo milho, ração para peixe e amendoim e produtos. Os resultados mostraram boa concordância entre as duas técnicas quanto à detecção de aflatoxina B1. O método ELISA mostrou-se mais rápido, menos trabalhoso, utilizando menos solventes orgânicos, porém apresentou resultados presuntivos positivos, tornando necessária a sua confirmação.

The efficiency of two enzyme-linked immunosorbent ELISA assays, commercially available in Brasil for detection of aflatoxin B1 were evaluated. These are screen tests designed to detect a minimum of 5 ppb and the other 20 ppb of aflatoxin B1 in corn extracts, were compared with the method of Soares and Rodriguez-Amaya which utilizes thin-layer chromatographic (TLC) and has a quantification limit of 4.0μg/kg (ppb). A total of 53 samples, including corn, fish feed, peanuts and its products were analysed. The results showed good agreement for aflatoxin B1 levels. The ELISA method was much faster, less laborious, used less organic solvents than the TLC method, but it showed some presumptive positive samples, for this reason it is necessary to confirm the positive samples.