Milk Salts: Interaction with Caseins

The topic of this article is the interaction of ions, notably Ca2+, Mg2+, K+, Na+, and H+, with caseins. These interactions are important in every product in which caseins are present and strongly affect the interactions, solubility, water-binding and other properties of the caseins. Caseins can be considered as polyelectrolytes, the behavior of which depends on both ionic bonds and on screening of charges. The formation of ionic bonds leads to charge neutralization on the caseins, whereas the screening of charges does not change the net-charge, but the range over which charges are active. Charge neutralization by addition of e.g., calcium chloride can lead to a loss of solubility of caseins. If, however, sufficient levels of phosphate are also present, casein micelles form. The casein micelles contain several hundred nanoclusters of calcium phosphate per micelle, the presence of which is crucial for casein micelle structure and stability. Understanding and controlling casein-salt interactions is crucial for casein functionality in dairy products and ingredients. This is an update of C. Holt, Milk Salts | Interaction with Caseins, In Encyclopedia of Dairy Sciences, Second Edition, edited by John W. Fuquay, Elsevier Ltd, 2011, https://doi.org/10.1016/B978-0-12-374407-4.00356-3.