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.