Comparação dos teores de selênio total em tecidos de camarão selvagem e de cultivo experimental para avaliação como matéria-prima para alimento funcional

Abstract

Selenium (Se) is an essential element to human health, because it is a micronutrient constituent of many enzymes. Known to exert a significant antioxidant effect, protecting cells against the effects of free radicals from the metabolism of oxygen, it is also essential for normal functioning of the immune system and metabolism. The diet is the main source of selenium intake for most organisms. In several regions of the planet, selenium intake is below the levels required for proper expression of selenoproteins. For this reason, there is interest in studying functional foods, owners of health benefits, enriched in this element. Seafood is among the main source of dietary selenium. With the overexploitation of the natural resources, aquaculture has become a powerful tool for the development of these foods. Thus, it is important to find the selenium content in an existing high consumption fisheries from the Northeast region, such as shrimp and cultured shrimp species Litopenaeus vannamei (Boone, 1931), which are possible sources of selenium to the population due the marked growth of shrimp farming activity in the state of Ceará in recent years. In the present study, the analysis of total Se content was performed in muscle and exoskeleton of shrimp captured from the native environment and marine shrimp grown in tanks at the Laboratory of Aquatic Animal Nutrition – LANOA (CEAC/LABOMAR). The samples were brought to the Laboratory of Coastal Biogeochemistry (LABOMAR/UFC) where it was used the analytical technique known as inductively coupled plasma mass spectrometry (ICP-MS), which is considered sensitive and specific for selenium analysis in complex matrices such as the organisms studied. Higher levels of selenium were found in wild shrimps in comparison with the cultivated ones, although selenium concentrations in both were high enough to ensure a good supply of this micronutrient in the human diet and there were differences in the age, weight and size between the groups (wild and cultivated shrimps). Concentrations found in the muscles of shrimps over the groups in accordance with the size of the organisms were 3,46 μg.g-1 to 5,16 μg.g-1 for the wild species and 1,76 μg.g-1 to 4,29 μg.g-1 from shrimp cultiveted. The values found for the exoskeleton of wild species were 9,44 μg.g-1 to 11,51 μg.g-1 and 4,07 μg.g-1to 5,36 μg.g-1 for shrimps cultiveted. Larger amounts of selenium found in the exoskeleton suggests a mechanism of detoxification that transfers the excess to the exoskeleton so that it can be released during molting. The aquafeed used in the experiment showed high levels of selenium though (2,11±0,34μg.g-1), similar to the highest values found in marine plankton, and the detoxification process presented suggests that the increase of the Se level would not be strategic to the extent of selenium levels in organisms grown, but the management of body weight for harvest. The exoskeleton from wild species and from shrimp cultiveted is a raw material rich in selenium for functional foods.