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

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 aw (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.