RELATIONSHIP BETWEEN THE SELENIUM CONTENT OF BRAZIL NUTS OF DIFFERENT SIZES AND THE LIPID FRACTION OBTAINED BY MECHANICAL PRESSING

Selenium is an essential micronutrient, widely present in Brazil nuts (Bertholletia excelsa), which is a valued seed with clinical and antioxidant action with benefits for human health. Although known, little is known about the direct relationship between the size of the nuts and the concentration of selenium (Se) due to the heterogeneous geographical distribution of selenium content among the seeds. The aim of this study was to investigate the relationship between selenium content and nut size (large, medium and small), to determine whether there are significant variations in selenium concentration. The seeds were pressed in a mechanical press to extract the lipid fraction. Individual packages of at least 3 kg were collected from different samples of dehydrated nuts from mills in the states of Amazonas and Pará. Se was analyzed by ICP optical emission spectrometry (OES) using atomic emission. The average concentrations were calculated in mg/kg in which the small nuts showed an average value of 25.51mg/kg, while the large and medium nuts showed values of 20.40 mg/kg and 22.39 mg/kg respectively, demonstrating that there was no significant relationship between size and selenium concentration. The oil samples showed a result below the detection limit, indicating that the transfer rate of Se to the oil was 0%. When compared with data in the literature, with Se contents in seeds ranging from 0.18 to 32mg/kg, the data found is in the same range. This finding is relevant for nutritional recommendations, since nuts with higher Se concentrations imply the need for moderate consumption to avoid toxicity. In conclusion, we observed that under the mechanical pressing conditions used, Se remains bound to the protein fraction and is not transferred to the lipid fraction (oil).