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

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 (Setot), 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 Setot 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 Setot 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.