Selenium and relation with protein in Brazilian mushrooms: exploring different species

Selenium is an essential micronutrient that participates in the structure of proteins with important functions such as regulation of the immune system, hormonal metabolism and reduction of the effects of inflammatory processes and oxidative stress in the human body, being considered a bioactive element. Mushrooms are possible sources of selenium in food, however, their nutritional value depends on a number of factors such as species, stage of development and composition of the cultivation substrate, and data on these levels in mushrooms produced in Brazil are scarce. The objective of this work was to evaluate the selenium content in 5 species of mushrooms: A - Champignon (Agaricus bisporus), B - Black Shimeji (Pleorotus ostreatus), C - White Shimeji (Pleorotus Florida), D - Shitake (Lentinula edodes), E - Portobello (Agaricus Portobello), as well as evaluating a relationship between the content of this mineral and the protein content. Selenium determination was performed by acid digestion, followed by hydride generation atomic absorption spectrometry (HG-AAS) and protein content by the Kjeldahl method. The moisture content (drying in an oven) was also evaluated to enable the calculation of nutrients on a dry basis. The results showed a great variation in the selenium contents among the different species of mushrooms evaluated, 8.06; 17.5; 29.1; 184; 241 ug/Kg (wet basis), for species B, D, C, A and E, respectively, and a variation of 81.7 - 3556 ug/Kg, on a dry basis. For species A and E, the consumption of a portion (80 g) provides 27 and 35%, respectively, of the recommended daily intake (55 µg for adults) of selenium, presenting themselves as important sources of this nutrient in the diet. The protein content also showed considerable variation between species, containing D, C, A, E and B respectively 17.6; 23.0; 30.2; 34.6 and 36.7 g/100g, with a general average of 28.4 g/100g, on a dry basis. With the exception of species B, it was observed that the increase in protein content was accompanied by an increase in selenium, generating a positive correlation (dry basis) of 0.93. The occurrence of sulfur amino acids such as methionine and cysteine, with substitution of sulfur for selenium, may be a possible source of this correlation in these mushroom species, since studies indicate that organic selenium corresponds to more than 85% of the total selenium content in mushrooms. . It is concluded that some mushroom species are sources of selenium, but there is a great variation in relation to the different species and a positive correlation of the selenium content with the protein content was also observed, which can be better studied.