RELATION BETWEEN COLLOIDAL CALCIUM-PHOSPHATE CROSS-LINKAGE AND RELEASE OF BETA-CASEIN FROM BOVINE CASEIN MICELLES ON COOLING

Colloidal calcium phosphate (CCP)-increased casein micelle dispersion (CMD) was prepared by adding calcium chloride and dipotassium phosphate to CMD adjusting the pH to 6.7. The content of casein aggregates cross-linked by CCP in casein micelles was increased from 49.3 to 68.3% by adding calcium and phosphate to CMD. The amount of serum casein released from casein micelles on cooling decreased with increasing CCP content. Since it is probable that β-casein is only released from β-casein which is not cross-linked by CCP in casein micelles, β-casein in casein micelles was divided into the three types: cross-linked by CCP; not cross-linked and released on cooling; not cross-linked and not released on cooling. When the CCP content was increased to a large extent, β-casein released on cooling decreased from 31.8 to 2.1% of the total β-casein, while β-casein cross-linked by CCP and β-casein which is not cross-linked and not released on cooling were increased from 46.2 to 69.9% and from 22.0 to 28.0% of the total β-casein, respectively. © 1990 by the Japan Society for Bioscience, Biotechnology, and Agrochemistry.