Physicochemical characteristic of artificial casein micelles prepared from buffalo milk: Effects of calcium, phosphate and citrate

Physicochemical characteristics of artificial casein micelles prepared from acid precipitated and sedimented ('first cycle') casein in the presence of calcium, phosphate and citrate have been studied. The casein materials were prepared from skimmed buffalo (Bubalis bubalis) milk. The artificial casein micelles prepared with the addition of calcium ions (34-50 mM) alone had lower heat and ethanol stabilities, and higher colloidal calcium content. The voluminosity and solvation values decreased when added calcium increased indicating that the overall size of the reformed micelles was most likely smaller in the presence of higher concentrations of calcium. Addition of phosphate (32-48 mM) to the artificial micelles containing normal amounts of calcium improved heat and ethanol stabilities, and increased the colloidal calcium and phosphate contents, indicating that micelle formation may commence with amorphous tri-calcium phosphate. The solvation value and the amount of soluble casein decreased with the addition of phosphate. Addition of citrate (6-10 mM) to the artificial casein micelles containing calcium and phosphate at concentrations similar to those found in unmodified milk further improved the ethanol and heat stabilities. Further addition of citrate resulted in decreased levels of colloidal calcium and phosphate.