Solubility of Tricalcium Citrate in Solutions of Variable Ionic Strength and in Milk Ultrafiltrates

Abstract

Solubility of tricalcium citrate was determined at 21[degree]C and 95[degree]C by dissolution in water and by precipitation from supersaturated solutions containing various proportions of C to citrate, and at pH between 4.4 and 8.2. Solubility product in solutions at equilibrium varied with ionic strength, according to the relation pks = 17.63 - 10.84 [square root][mu], but was unaffected by variations in pH and temperature nor by the presence of Mg or phosphate ions. Milk ultrafiltrates were shown to be saturated with tricalcium citrate, i. e. the calculated pks values agreed with the solubility product in all but 2 of the 15 samples tested, and composition of 2 ultrafiltrates was unaffected by agitation with crystals of tricalcium citrate.