Dissociation of native casein micelles induced by sodium caseinate

The effect of addition of sodium caseinate (NaCas) to aqueous solutions of casein micelles was studied at pH 6.7. Addition of NaCas leads to reduction of the turbidity and to a decrease of the fraction of proteins that precipitates during ultracentrifugation. The calcium and orthophosphate concentrations in the supernatant were found to increase with increasing NaCas concentration. The results show that addition of NaCas causes release of colloidal calcium phosphate and dissociation of native caseine micelles. The process is controlled by the weight fraction of NaCas in the mixture and dissociation is complete when the fraction exceeds 75%. The efficacy of NaCas as chelating agent for casein micelles is compared with that of polyphosphate reported in the literature. The liberated calcium and orthophosphate are bound to the added NaCas, which leads to aggregation at higher casein concentrations. (C) 2015 Elsevier Ltd. All rights reserved.