Increased loading of vitamin D₂ in reassembled casein micelles with temperature-modulated high pressure treatment

Native casein micelles were treated (incubated) with vitamin D₂ at different hydrostatical pressures (0.1, 200, 400, and 600MPa) and temperatures (10-50°C) in order to load the vitamin. Pressure induced the release of α_s-, β- and κ-casein and calcium from the micelle into the soluble phase. During the pressure stable reassembled micelles were created due to a structural rearrangement of hydrophobic interactions between the hydrophobic domains of the caseins and vitamin D₂. Treatment at 600MPa and 50°C increased the loading of vitamin D₂ per casein from 2.2±0.2μg/mg (native sample) to 10.4±0.2μg/mg. The reassembled micelles presented an average hydrodynamic diameter of 272±10nm and contained 8.1, 10.3 and 0.8mg of α-, β- and κ-casein, respectively, per 100mg casein.