Aflatoxins evaluation on in-shell and shelled dry Brazil nuts for export analysed by LC-MS/MS - 2006 and 2007 harvests

Dry in-shell and shelled Brazil nuts from two different harvests were evaluated for aflatoxins by LC-tandem mass spectrometry with atmospheric pressure chemical ionisation in the positive mode. A total of 171 samples of Brazil nuts for export, comprising 108 in-shell and 63 shelled (large, medium and small sizes) were collected in a factory located at Manaus city, State of Amazonas, in the Brazilian Amazon. They were collected from big bags (in-shell nuts) and sorting tables after size classification (shelled nuts), immediately after processing, from April to May of 2006 and 2007. Samples also had their moisture content (mc) and water activity (aw) analysed and the out- and in-door environmental conditions (relative humidity (RH) and temperature) were monitored during the sampling period. From all the samples analysed from both harvests, only 8.7% (14) of the nuts contained aflatoxin at levels >4 µg/kg (EU maximum level). This corresponded to a total number of 11 and 3 for the in-shell and shelled nuts, respectively. The 2007 harvest nuts had fewer samples with aflatoxin levels higher than 4 mg/kg, with 2 for both in-shell and shelled nuts each. The analytical method was selective, sensitive and fast (total run time of 7 min). The RH in the factory ranged from 77.1 to 95.8% (2006) and 76.9 to 91.0% (2007) being the highest RH reached in April. The data showed that the nuts' aflatoxin levels varied with the year of harvest and cleared up the speculation about which type of dried nut has aflatoxin levels safe enough for commercialisation.