Effects of Se(IV) or Se(VI) enrichment on proteins and protein-bound Se distribution and Se bioaccessibility in oyster mushrooms

A successful mushroom enrichment process must produce foods that have compounds potentially absorbed by the human body. In this study, Pleurotus ostreatus and Pleurotus djamor mushrooms were grown on organic substrate supplemented with different Se(IV) and Se(VI) concentrations, and evaluated in the following features: Fruiting bodies morphology; Se uptake and accumulation; Distribution of proteins and protein-bound Se; Se species identification on enzymatic extracts; Se bioaccessibility; and Distribution of bioaccessible protein-bound Se. Pleurotus djamor grown on Se(IV)-supplemented substrate showed the greatest potential to uptake and accumulate Se. For Se species screening, selenomethionine was identified in white oyster mushroom, while selenomethionine, selenocystine, and Se-methylselenocysteine in pink oyster mushrooms. In soluble fractions from in vitro gastrointestinal digestion assays, Se showed high bioaccessibility (>94%). Lastly, bioaccessible Se species were found to be mainly associated to LMW (<17 kDa) in Pleurotus ostreatus (74%) and Pleurotus djamor (68%) grown on Se(IV)-supplemented substrates.