Susceptibility of the In-shell Brazil Nut Mycoflora and Aflatoxin Contamination to Ozone Gas Treatment during Storage

Abstract

The effect on fungi load, toxigenic Aspergillus strains and aflatoxin (AFL) contamination of stored in-shell Brazil nut (Bertholletia excelsa H.B.K.) ozone (O₃) gas treated were evaluated. Groups of nuts obtained from retail market were submitted to O₃ atmosphere at different concentrations (10, 14, 31.5 mg/l) and stored for 180 days. The O₃ treatment affected Brazil nuts mycoflora growth, reduced their moisture content (mc) and degraded AFLs. From the three O₃ concentrations applied, 31 mg/l (5 hours exposition) was able to successfully destroy fungi contamination (initial: 4.83 logcfu/g to ng-no grow), including the Aspergillus flavus and A. parasiticus species, since Day One after application. On the other hand, they were still able to grow, at the lower O₃ concentrations (10; 14 mg/l), however only in the first days of storage and at reduced number though (from 4.83 to 3.5/3.3 logcfu/g, respectively). Despite of the O₃ concentrations applied, AFLs were not detected in all nut samples O₃ treated since Day One of application up to the method LOQ of 1.34 µg/kg except for 10 mg/kg). As expected, a reduction of mc (9.43 to 7.32 %) and a_w (0.82 to 0.63) due to gas stream application was registered throughout the storage period, which increased with the O₃ time of exposure resulting cruncher Brazil nuts. Apart from low cost and simple technology to be applied during storage in-land or in containers before shipping, O₃ treatment it is a promising alternative for contamination control and is environment friendly.