Ion exchange processing of skim-milk for food use

Abstract

SUMMARYIon exchange is a unit operation which has several applications in the processing of skim-milk and whey. For example, in the field of whey processing, ion exchange is used in demineralization, lactose hydrolysis and in the pre-treatment of whey prior to protein recovery. In the case of skim-milk, applications include the manufacture of low Na milk and pre-acidification of skim-milk in casein manufacture. However, the ion exchange treatment of skim-milk to replace Ca ions with Na ions leads to far more fundamental changes with regard to the native protein conformation.The effect of Ca removal from skim-milk is essentially to disrupt the native casein micelle structure into unassociated molecules of Na caseinate. Skim-milk modified in this way shows increased stability to alcohol and heat and increased functionality of the skim-milk protein in terms of water binding, emulsification and foaming capacity. The viscosity of Ca-reduced skim-milk is also substantially increased.The improved functionality of Ca-reduced skim-milk makes the latter a potentially useful food ingredient in products where the above mentioned properties are important.

pH-Induced physicochemical modifications of native phosphocaseinate suspensions: Influence of aqueous phase

“…This is explained, on the one hand, by changes in the structure of micelles probably due to the displacement of calcium from the CCP by sodium and, on the other hand, by the increase of the ionisation of caseins due to the decrease of activity coefficients. The latter led to the increase of the micelle voluminosity and also of the functional properties of casein mate rial (Burgess, 1982;Snoeren et al, 1984;Creamer, 1985).…”

Influence of calcium depletion on iron-binding properties of milk

“…Ion exchange of multiva-lent cations (especially calcium) with monovalent ions (sodium, potassium) has been performed to improve the functionality and the stability of milk products (Lyman et al, 1933;Burgess, 1982;Bhaskar, 2010) and to manufacture novel products (Bhaskar, 2010). Up to 80% of the calcium in milk can be depleted using this technique (Ranjith et al, 1999).…”

“…Up to 80% of the calcium in milk can be depleted using this technique (Ranjith et al, 1999). The depletion of calcium from milk induces changes to the structural and physicochemical properties of the milk (Burgess, 1982;Lin et al, 2006;Grimley et al, 2010), but the effects on the iron-binding properties are not known. The present work explores the effects of calcium depletion on the binding of iron to milk proteins.…”