Effect of feed selenium supplementation on milk selenium distribution and mozzarella quality.

In the present study, the effect of feed Se supplementation on the Se content of raw milk and mozzarella cheese as well as the effect on cheese quality and functionality were determined. The Se milk was produced by supplying dairy cow feed with Se yeast (0.3mg of Se/kg of dry matter), resulting in a Se concentration in milk of 35.81µg/L. The fat, casein, and whey protein of Se milk were separated by ultracentrifugation, and the Se content was determined by atomic absorption spectroscopy. The Se distribution in different milk fractions of fat, casein, and whey protein were 9.82, 45.56, and 44.62%, respectively. The Se mozzarella cheese was made by Se milk, and the composition and texture of Se cheese did not significantly differ from that of the control. However, the functional properties (meltability, flowability, and stretchability) of the Se cheese were better after 8 wk of storage. Moreover, the pH and water activity were lower in Se cheese, which decreased the total plate count. The Se content in mozzarella cheese was 4 fold higher than that in milk, and Se was found in the whey, hot water, and brine collected during cheesemaking. Organic and inorganic Se was found in the Se cheese after 8 wk of storage, and most Se peptides detected after storage were Se-Met and Se-Cys. The results of this study show that feed Se supplementation can improve the Se content of milk and cheese without affecting mozzarella cheese quality.