Role of individual milk salt constituents in cross-linking by colloidal calcium phosphate in artificial casein micelles.

Abstract

Artificial casein micelles were prepared at a casein concentration of 2.5% with various salt compositions, and the content of the casein aggregates cross-linked by colloidal calcium phosphate (CCP) was determined by high-performance gel chromatography on a TSK-GEL G4000SW column, using 6 m urea-simulated milk ultrafiltrate as the effluent. When phosphate was incorporated into calcium caseinate micelle systems, the casein aggregates cross-linked by CCP appeared. In these micelle systems, not all of the formed calcium phosphate seemed to participate in cross-linking, because part of the calcium phosphate was in the urea-insoluble form. When micelles were prepared at 30 mm calcium and 22 mm phosphate, the content of the casein aggregates cross- linked by CCP was higher in the presence of 10mm citrate than in the absence of citrate. The precipitate of calcium phosphate formed in the presence of citrate had cross-linking ability, whereas the precipitate formed in the absence of citrate did not. It is suggested...