Unraveling the accumulation and localization of selenium and barium in Brazil nuts using spectroanalytical techniques

Brazil nuts are native from the Amazon rainforest and their nuts are consumed worldwide having good sensory acceptability. However, knowledge gaps remain concerning elemental composition, localization, and interactions in Brazil nuts. This study presents a detailed assessment regarding the concentration and localization of relevant elements in Brazil nuts using different and complementary spectroanalytical techniques. Samples were collected from six sites of the Brazilian Amazon (Acre, Rondônia, Amazonas, Roraima, Pará, and Amapá) and showed results for selenium (Se) concentration ranging from 0.46 to 356 μg g−1 and barium (Ba) from 12.5 to 7,177 μg g−1. Then, a linear regression model fitted between Se and Ba concentration in Brazil nuts provided an R2 = 0.30. The spatial distribution of major and trace elements in Brazil nuts varied depending on the site of origin and concentration in the sample. The 2D maps performed via μ-XRF showed that Se accumulates mainly in the outer parenchyma tissue of Brazil nuts seeds forming a “ring” shape while Ba tends to accumulate in the epidermal tissue. The possibility of forming compounds of low solubility in Brazil nuts such as BaSO4 and BaSeO4 tends to increase when Ba and Se are higher respectively in the samples studied.