Incidence of Aspergillus flavus, Aspergillus parasiticus and aflatoxins in Brazil nuts in the Amazon forest environment.

摘要

This work aimed to evaluate, in the Amazon Forest environment, the effect of time on contamination of Brazil nuts with Aspergillus flavus, Aspergillus parasiticus and aflatoxins after falling of the pods. Samples were collected at three different times and analysed for water activity, potentially aflatoxigenic fungi A. flavus and A. parasiticus, other fungi and aflatoxins. The mean values for the parameters tested were: water activity 0.98; A. flavus and A. parasiticus 1.3x101 colony forming units (cfu)/g; other fungi 3.2x103 cfu/g; aflatoxin B₁ 0.073 micro g/kg, aflatoxin B₂ 0.009 micro g/kg, aflatoxin G₁ 0.034 micro g/kg and aflatoxin G₂ 0.007 micro g/kg. The incidence of A. flavus and A. parasiticus was not significantly affected by the time, during which the pods were on the forest soil. Moreover, aflatoxins levels were low during the whole study period, suggesting that adverse forest conditions were not the main factor that stimulate the production of aflatoxins.