Irradiação gama na redução de contaminação de castanha-do-brasil (bertholletia excelsa, H.B.K) por aflatoxinas

Abstract

Brazil nut (Bertholletia excelsa, H.B.K) is a nutritionally rich food and is widely used both in its natural form for direct consumption, as well as in granulated and ground formats for use in bakery products, for example. It is a food susceptible to contamination by fungi producing aflatoxins, which are toxic to human health. Thus, the control of fungal and mycotoxigenic contamination is important both to avoid major economic losses and socioenvironmental impact in the Amazon region, and for public health reasons. In view of this, the objective of this study was to evaluate the effects of gamma radiation at doses of 1, 10 and 20 KGy in whole and granulated Brazil nuts, contaminated by aflatoxins and artificially inoculated with Aspergillus flavus in addition to analyzing the impact of radiation on oil quality and composition of fatty acids and volatile compounds, as the nut is a product rich in unsaturated fatty acids that favor oxidative rancidity. It was observed that all doses tested were able to inhibit fungal growth in whole and granulated samples. As for contamination by aflatoxins, the dose of 20 KGy was the one that caused the greatest reduction in the total Aflatoxins of the granulated nuts, reducing 20%, while in the whole the reduction was only 6%. All doses caused an increase in the acidity and peroxide indices of both formats, however this increase is still within the limit allowed to validate the quality of vegetable oils. The composition of fatty acids varied according to the radiation dose used and the shape of the nut. The granulated samples had a very similar composition, with a slight increase in saturated fatty acids, especially stearic acid, and a decrease in unsaturated acids. In the whole samples, the dose of 1 KGy was the one that most changed the composition of fatty acids, causing an increase in saturated acids, especially palmitic acid. Despite this, this change in fatty acid profiles did not vary much from that commonly found in Brazil nuts. It is concluded that gamma radiation shows a promising treatment in the reduction of aflatoxins and elimination of aflatoxigenic fungi in Brazil nuts. In addition, the shape of the Brazil nut influenced the action of radiation.