Selenium enriched mushrooms as food additives and dietary supplements

Abstract

Edible and medicinal mushrooms have been used worldwide due to their nutritional value and known pharmaceutical properties, which are related to the physiologically beneficial substances in the form of primary and secondary metabolites. Their chemical composition and biological activity depend on the medium on which they grow and applied supplementation. Numerous studies have shown that mushrooms can absorb selenium (Se) during growth on the fortified solid substrate or liquid medium, in a concentration that can meet the daily needs of humans. The capacity of some mushroom to absorb Se depends on multiple factors, including mushroom strain, composition of the medium, ecological pa rameters as well as on the form and concentration in which this mineral is added to the me dium. It was previously reported that strains Pleurotus sp, Agaricus bisporus, Ganoderma lu cidum, and Cordyceps militaris absorbed high concentrations of Se when sodium selenite or selenate were applied. However, higher toxicity of inorganic salts that suppressed mycelium growth of Hericium erinaceum, Lentinus edodes, Coriolus versicolor, and Pleurotus spp. com paring to modified zeolites with Se and organic selenitetriglycerides from Selol, Se-yeast, and selenourea was proven. Chemical characterization of polysaccharide and methanol ex tracts isolated from fruiting bodies or mycelia culture showed that most of the Se-enriched mushrooms had a higher content of total carbohydrates (especially β-glucans), proteins, fla vonoids, and phenols comparing to the non-enriched samples. As a consequence, selenized mushrooms showed improved antioxidant and antimicrobial properties. A significant per centage of Se was incorporated not only in the form of L-selenomethionine, but also other organic compounds, such as biologically active polysaccharides. It is believed that the syn ergism of Se and bioactive polysaccharides present in fungi could enhance their antitumor and immunostimulating functions, which lead to numerous health benefits. Obtained re sults classify Se-polysaccharides as promising dietary supplements and Se-enriched mush rooms as delicious functional food or food additives, due to the slow release of selenium and lower toxicity compared to the inorganic compounds. Selenium fortified mushrooms and their extracts used as food additives are expected to prolong the shelf life of the food products since some of them are proved to exhibit higher superoxide dismutase and catalase activity retaining their quality, aroma, and color for a long time of storage.