Effect of gamma radiation on the infected yellow corn and peanuts by a.flavus

Pure aflatoxins and deliberately infected yellow corn and peanuts with A. flavus were separately exposed to gamma radiation at 5, 10 and 20 KGy. The levels of pure aflatoxins were decreased by increasing the radiation dose. The pure aflatoxins G1 and B1 were the most radio- sensitive while B2 was the most radio-resistant than the other isomers. B1 and G1 toxins were completely destroyed at irradiation doses of 10 and 20 KGy, respectively. The reduction percentages of aflatoxins in the deliberately infected yellow corn and peanuts demonstrated that, the aflatoxins B2 and G2 were the most radio- sensitive than that of their analogy compounds [B1 and G1]. The toxicity index values for the infected yellow corn and peanuts were decreased by increasing the irradiation dose. The gamma-rays even at 20 KGy was not effective in destroying completely the toxins since only 83% reduction of aflatoxins was achieved

Effect of gamma irradiation on aflatoxin production by aspergillus parasiticus

Exposure of aflatoxins produced by A. parasiticus grown on sterile raw peanuts to specific gamma irradiation doses induced reduction in aflatoxins with increasing gamma irradiation dose than did aflatoxin from non-irradiated sterile raw peanuts [control]. The reduction of aflatoxins ranged from 9.3 to 29.7%, 13.9 to 37.3%, 0.96 to 16.8% and 0.72 to 60.3% for AFB1, AFB2, AFG1 and AFG2, when the culture was irradiated at 0.5 to KGY, respectively. On the other hand, non- sterile raw peanuts that was inoculated with conidia of the fungus and then incubated for 2 weeks at 30C following irradiation resulted in reduction in aflatoxins ranged from 18.2 to 89%, 26 to 96%, 35.4 to 85.2% and 17.3 to 76.4% for AFB1, AFB2, AFG1 and AFG2, respectively. Irradiated raw peanuts culture following inoculation with conidia of the fungus and then incubated for 2 weeks at 30C resulted in reduction of toxin [s] production ranged from 4.9 to 28.4%, 16.8 to 54.7%, 1.71 to 18.6% and from 9.13 to 30.4% in AFB1 AFB2, AFG1 and AFG2 when cultures irradiated at 0.5 to 5 KGY, respectively. Inoculation of either sterile or non-sterile raw peanuts cultures following irradiation resulted in completely degradation of aflatoxin [s] at higher doses between 2.5 to 5 KGy for sterile substrates and at 2.5 to 4 KGy for non-sterile raw peanuts

Comparación de los efectos provocados por el calor y la irradiación sobre Aspergillus parasiticus / Comparison of effects resulting from the application of physical treatments to Aspergillus parasiticus

El propósito de este trabajo fue estudiar la inhibición de la produción de aflatoxinas asociadas al crecimiento del hongo Aspergillus parasiticus NRRL 2999, mediante el empleo de radiaciones ionizantes. El hongo fue cultivado en arroz de tipo comercial en condiciones de temperatura y humedad ideales para la producción de toxinas. Los cultivos así obtenidos fueron irradiados con dosis de 1,5 kGy* (2D10) al cabo de distintos tiempos de desarrollo, observándose que la máxima inhibición de la producción de toxinas se alcanzaba al irradiar cultivos de 20 horas de desarrollo. Asimismo, se estudió el efecto del calor y su combinación con la irradiación sobre la producción de aflatoxinas, la cual fue seguida a lo largo de 11 días de desarrollo de los cultivos. El contenido de toxinas de los distintos cultivos se dosó por dilución a estinción en cromatografía de capa delgada. Los resultados obtenidos mostraron que, tanto un calentamiento de 15 min a 55-C, como la irradiación de los cultivos con una dosis de 1,5kGy, disminuyen el contenido de toxinas, siendo este último processo el más efectivo. Más aún, la combinación de estos dos agentes físicos, irradiando los cultivos inmediatamente después de ser sometidos al calentamiento, reduce los niveles de toxinas por debajo de los límites de detección sugeridos por las organizaciones mundiales de la salud