Effect of Rennet Type on Selenium Retention and Its In-Vitro Bioaccessibility in Se-Enriched Edam Cheese: An...

Dairy products, particularly cheese from selenium-enriched milk, provide an effective vehicle for Se supplementation in the human diet. This study examined how coagulant type and ripening affect total Se (Se_tot), free selenomethionine (SeMet) formation, and in vitro Se bioaccessibility in Edam-type cheeses produced from biofortified milk (73 µg L^-1 Se). Cheeses were manufactured in a single batch using either animal (calf) or microbial (Rhizomucor miehei) rennet and ripened for six weeks under controlled laboratory conditions. Although Se_tot declined in both cheeses, microbial-rennet cheese exhibited a rapid 13.5% loss in week 1, whereas animal-rennet cheese showed a more gradual decrease. After six weeks, both cheeses retained about 40 µg Se per 100 g. A robust 20 mmol L^-1 ammonium acetate extraction coupled with LC-ICP-MS enabled detection of free SeMet at concentrations as low as 0.0003 µg g^-1 Se and revealed a linear increase throughout ripening in both cheeses. In vitro Se bioaccessibility reached 64% of Se_tot for animal-rennet cheese and approached complete release in microbial-rennet cheese. These findings suggest that the choice of coagulant may influence not only Se retention, but also the gastrointestinal accessibility of protein-bound Se in Edam-type cheese.