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In vitro activity of the Brazil nut (Bertholletia excelsa H.B.K.) oil in aflatoxigenic strains of Aspergillus parasiticus

Martins, Maristela, Klusczcovski, Ariane Mendonca, Scussel, Vildes Maria
European food research & technology 2014 v.239 no.4 pp. 687-693
Aspergillus parasiticus, Bertholletia excelsa, acidity, aflatoxins, antifungal properties, foods, fungi, growth retardation, in vitro studies, microbial growth, oils, preservatives, refractive index, thin layer chromatography, toxigenic strains
The growing demand for safe foods without preservatives has fostered research to investigate the effects of natural compounds on microorganisms. Accordingly, an in vitro study was carried out to determine physico-chemical characterization and investigate the antimicrobial effects of Brazil nut oil on toxigenic strains of Aspergillus. The antifungal activity testing was carried out isolating A. parasiticus by transferring the strains to the center of the plates containing treatments with different concentrations of Brazil nut oil. The plates were incubated for 8 days at 28 °C with subsequent extraction of toxins. The aflatoxins AFB₁AFB₂, AFG₁, and AFG₂were determined by thin-layer chromatography. The values found for acidity, refractive index, and density ranged from 0.3512 to 0.7092, 1.4670 to 1.470, and 9.2 × 10²to 16.7 × 10², respectively. The results obtained showed that the effect of Brazil nut oil on the growth diameter of the fungal colony was time and concentration dependent. After 8 days of incubation, all treatments showed better fungal growth inhibition compared with that of the control. Total inhibition of aflatoxin production by the strain (LOQ of the method: 2 g/kg) was also observed in the medium containing the oil, while in the control treatment, AFB₁, AFB₂, and AFG₁were produced by the inoculated strain A. parasiticus.