Enriquecimento e biodisponibilidade de selênio no cogumelo de Pleurotus ostreatus

• Autor(a) principal: Silva, Marliane de Cássia Soares da
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5306
• topic: Casca de café; Eficiência biológica; Selenito de sódio; Cogumelo enriquecido; GPx; Selênio no plasma sanguíneo; Coffee rusk; Biological efficiency; Sodium selenite; Enriched mushroom; GPx; Plasma selenium; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::MICROBIOLOGIA AGRICOLA

Selenium (Se) is one of the essential nutrient for several physiological functions that include activity of the proteins catalytic centre, increase of the immune system functions and reduces the cancer risk, besides being the essential component of the antioxidative enzyme, glutatione peroxydase (GPx). In areas where the soil present low Se concentration, such as the Brazilian soils, the agricultural products also presents low concentrations of this element and this deficiency causes serious risks for the human health. Besides the plants, mushrooms have the capacity to accumulate great quantities of Se, and, this characteristic associated to the elevated nutritional value, being a source of proteins, carbohydrates vitamin B1, B2 and B3, calcium and iron, makes of mushrooms aliments that alleviate various nutritional deficiencies. The bioavailability is defined as the proportion of ingested nutrient that is used for normal physiological functions or stored, so, it must be considered in the nutritional food evaluation. The objective of this work was to enrich and determine the bioavailability of Se in Pleurotus ostreatus mushroom. The mushrooms were produced in coffee rusk as substrate base enriched with different concentration of Se 3,2; 6,4; 12,8; 25,4; 51; 76,4; 102 mg kg-1), using sodium setenite. Biological efficiency (BE) and Se, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, N, P, Pb and Zn concentration were evaluated, in three consecutive flushing, in the same substrate. For Se bioavailability, 64 rats (Wistar) were fed using P. ostreatus mushrooms enriched or not with Se, and as positive control sodium selenite was used. BE of the mushrooms was affected by both flushing number and Se concentration in the substrate. The highest value of BE among 13,06 to 37,56% were observed at the first flushing, white BE among 2,47 to 11,09% were obtained at third flushing which period varied from 43 to 79 days after inoculation. Mushrooms groduced in the substrate with 3.2 mg kg -1 present about 55 &#956;g g-1 of Se in the dry matter. The maximum Se concentration absorbed by the fungus was when it was growth in the substrate with 0.64 mmol kg-1 of Se, although the best use of added Se occurred with 12,8 mg kg-1 where 34% of added Se was present in the mushroom. Biological assay showed that Se present in the mushroom was able to cross the intestinal barrier reaching the blood circulation of the animals. The rats using mushroom Se enriched mushroom presents 700 &#956;g L- 1 of Se in the blood plasma, while ones receiving the same quantity of Se as sodium selenite present about 500 &#956;g L-1 (P<0,05). The plasma GPx enzyme activity was about 2000 nmol min-1 mL-1 in rats fed with all diets (P>0,05). The blood plasma protein showed no difference among diet in relation to chromatographic profiles. The peptide in high concentration was detected at 24 min presenting molecular weight estimated to 7,7 kDa. However, Se concentration in this peptide was 2.76, 6. 90 and 5.27 &#956;g L-1 in animals fed, respectively, without Se, Se enriched mushroom and sodium selenite. Based on these results, it can be concluded that: mushroom production was stimulated by low concentration of Se added to the substrate; BE in the first flushing is higher than second and third; concentration of 12,8 mg kg-1 of Se in the substrate resulted in the best use of added Se; Se in the mushroom was better absorbed bay the animals than when as sodium selenate. Selenium present in the mushroom shows high bioavailability, since Se was detected not only in the blood plasma but also into the seric peptides; Over all, P. ostreatus shows an excellent food source of Se.