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

- Increasing pressure at low temperatures enhances release of caseins and calcium
- Increasing pressure at high temperatures favours re-association of micelle components
- Pressure/temperature modulation allows reassembly of micelles with altered properties
- High-pressure enhances loading of vitamin D2 in stable reassembled casein micelles

Native casein micelles were treated (incubated) with vitamin D2 at different hydrostatical pressures (0.1, 200, 400, and 600 MPa) and temperatures (10-50 °C) in order to load the vitamin. Pressure induced the release of αs-, 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 600 MPa and 50 °C increased the loading of vitamin D2 per casein from 2.2 ± 0.2 μg/mg (native sample) to 10.4 ± 0.2 μg/mg. The reassembled micelles presented an average hydrodynamic diameter of 272 ± 10 nm and contained 8.1, 10.3 and 0.8 mg of α-, β- and κ-casein, respectively, per 100 mg casein.