Selenium and Aflatoxin levels in raw Brazil nuts from the Amazon Basin.
Whereas selenium (Se) is an important antioxidant in human metabolism to prevent cancer; aflatoxins are highly carcinogenic. Brazil nuts from Eastern and Western Amazon regions were evaluated to find any relationship between Se and aflatoxins levels. A total of 80 (in-shell and shelled) nuts samples were collected directly from different forest sites and analyzed for Se by atomic emission spectrometry and aflatoxins by liquid chromatography tandem mass spectrometry. The limit of quantification (LOQ) for Se was 2.0 mg/kg; and LOQ for total aflatoxins was 0.390 microg/kg. Nut Se levels from the Eastern region were higher than the Western; in addition to the aflatoxins. The moisture content (mc) and water activity ( a w) of the raw nuts from the two regions did not present a significant difference; for either in-shell or shelled. The mc was 24.5% (minimum of 20.1% and maximum of 30.4%) and 22.1% (minimum of 14.6% and maximum of 28.9%) and a w of 0.85 for both regions. Further studies need to be carried out to discover the role of Se on fungi growth stress and aflatoxin production mechanisms.
Characteristics of in-shell Brazil nuts and their relationship to aflatoxin contamination: criteria for sorting.
External characteristics of in-shell Brazil nuts were evaluated for dimensions (length and face width); weight; chromaticity; and shell thickness. The internal characteristics evaluated were moisture content (mc); aflatoxin contamination (analyzed by LC-MS/MS); and shell/nut ratio. According to their length; Brazil nuts were classified in three groups: I; II; and III; corresponding to large; medium; and small sizes; respectively. It was possible to establish the following parameters as standards for normal/healthy nuts: length (53.2; 43.9; and 36.6 mm); weight (12.9; 8.8; and 6.3 g); and shell chromaticity components (L*; 38.3; 39.5; and 41.6; a*; 8.0; 7.9; and 7.8; and b*; 17.6; 18.0; and 18.7); for the three groups; respectively. The mean of shell thicknesses were 1.92 and 2.68 mm taken from each face and nut top. The nuts; classified as small (Group III); presented aflatoxin B1 contamination at a level of 5.62 microg/kg. The Groups shell/nut ratios were 1.2; 1.2; and 1.3 for normal whole and healthy nuts. No aflatoxin was detected in Groups I and II. The data obtained from the Brazil nut measured characteristics can help to distinguish healthy/safe and deteriorated nuts and will be useful for Brazil nut sorting and machine development.