This work reports the application of oxygen-(O2-) reducing atmosphere methods on stored shelled Brazil nut (Bertholletia excelsa H.B.K.) packs aiming to evaluate the degree of aflatoxin degradation, nuts lipid oxidative stability, fungi control, and hygienic conditions improvement. The methods applied were (a) ozone: O3, (b) carbon dioxide: CO2, and (c) O2 absorber pads with and without vacuum. From all modified atmospheres evaluated, the best performance was obtained with O3, either with or without vacuum. It was the only nut treatment that was able to degrade aflatoxins. None of the spiked (AFLs: 15？μg·kg？1) nut samples O3- treated had aflatoxins detected up to the LC-MS/MS method LOQ (0.36？μg·kg？1 for total AFLs), thus producing safer nuts. Also it kept the fatty acid oxidation indicator—malondialdehyde stable and improved the sensory attributes for consumer acceptance. In addition, the destruction of fungi and yeast was observed since the O3 application (from ？cfu/g to NG = no growth). All other treatments stabilized and/or inhibited microorganisms' growth only. By adding CO2 gas also played an important role in the nut quality. Regarding cost, gaseous O3 showed to be of low cost for application in the nut packs. 1. Introduction In nature, Brazil nuts (Bertholletia excelsa H.B.K.) that grow in the Amazon forest may get contaminated by fungi and aflatoxins [1–3], as other tree nuts. The aflatoxigenic Aspergillus species that have been isolated from Brazil nuts are A. flavus, A. parasiticus, and A. nomius [4–7]. Their growth is directly related to the climate conditions of that region and to the conditions during their storage, transport, and commercialization, if there is no control of moisture content (m.c.) and temperature. That can also occur if nuts are packaged in a microclimate rich in oxygen (O2) and m.c. enough to allow microorganisms to grow [1, 8]. Studies have reported the use of modified atmospheres (MA) in food storage, extensive to packaging, to reduce O2 concentration by adding gases such as nitrogen, carbon dioxide (CO2), and ozone (O3) which lead to microorganisms (fungi, yeast, and bacteria) inhibition, maintenance of lipid stability, and reduction of grains/nuts/vegetable respiration [9–14]. Vacuum also is an alternative for O2 reduction and in recent years the addition of O2 absorber pads (which contains a mixture of iron salts) have been the newest alternative in packaged food [15–17]. Studies have reported O3 and CO2 effect on controlling microorganism growth in several agricultural commodities [13, 18–21]. CO2 is a promising
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