STRUCTURE OF CASEIN MICELLES STUDIED BY SMALL-ANGLE NEUTRON-SCATTERING

The structure of casein micelles has been studied by small-angle neutr on scattering and static light scattering. Alterations in structure up on variation of pH and scattering contrast, as well as after addition of chymosin, were investigated. The experimental data were analyzed by a model in which the casein micelle consists of spherical submicelles . This model gave good agreement with the data and gave an average mic ellar radius of about 100-120 nm and a submicellar radius of about 7 n m both with a polydispersity of about 40-50%. The contrast variation i ndicated that the scattering length density of the submicelles was lar gest at the center of the submicelles. The submicelles were found to b e closely packed, the volume fraction varying slightly with pH. Upon a ddition of chymosin the submicellar structure remained unchanged withi n the experimental accuracy.