Fungal contamination of Brazil nuts can cause health problems, which limits their worldwide consumption
and leads to economic restrictions for the producing regions. In this study the contamination of
Brazil nut seeds by aflatoxin-producing fungal strains was investigated. It was observed that of the 31
strains isolated from the inside of the seed coat, 39% showed aflatoxigenic potential, indicating a high
level of contamination by microorganisms which produce aflatoxins, which have strong carcinogenic and
hepatotoxic activity. The moisture content and water activity are determining factors for fungal growth.
Measurements of the dielectric properties at microwave frequencies of the Brazil nut shell and the kernel
reveals that the shell has a higher loss tangent (0.12) at 30 C relative to the kernel (0.06) and high values
for the penetration depth of both shell (20 cm) and kernel (35 cm) that are related to their chemical
composition. Microwave heating was employed leading to reductions in the moisture content (46.4%)
and water activity (20%). Furthermore, the effectiveness of microwave dielectric heating as a disinfestation
process for contaminated nuts was investigated, showing that colonization inside the shell
decreased by 61.67% and on the kernel by 81.75%, without damaging the organoleptic properties of the
Brazil nut seeds.