Effect of calcium sequestration by ion-exchange treatment on the dissociation of casein micelles in model milk protein concentrates

• Published in: Food hydrocolloids 2016-10, Vol.60, p.59-66
• Main Authors: Xu, Yuting, Liu, Dasong, Yang, Hongxu, Zhang, Jie, Liu, Xiaoming, Regenstein, Joe M., Hemar, Yacine, Zhou, Peng
• Format: Article
• Language: English
• Subjects: Calcium; Casein; Casein micelles; CCP nanoclusters; Colloidal Ca; Concentrates; Decalcification; Ion exchange treatment; Micelles; Milk; Milk protein concentrates; Nanostructure; Small angle X ray scattering; Turbidity
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2016.03.026

This study investigates the effect of partial depletion of Ca from milk protein concentrates (MPCs) on the dissociation of the casein micelles. Series of MPCs with 0, 10.5, 19.6, 29.6, 38.7 and 83.6% decalcification were produced from the ultrafiltered-diafiltered retentate of skim milk using ion exchange treatment. The amount of caseins dissociated from the casein micelles increased when decalcification was increased from 0 to 38.7%, while both the relative turbidity of the retentate and the z-average hydrodynamic diameter of casein micelle decreased markedly. Increasing decalcification to 83.6% caused no significantly additional changes in the amount of the dissociated caseins and the relative turbidity. As for casein micelles and colloidal calcium phosphate (CCP), transmission electron microscopy and small angle X-ray scattering (SAXS) showed that the micelle structure and CCP nanoclusters, respectively, were gradually dissociated at the beginning of the decalcification (0–38.7%), particularly at 38.7% where most of the casein micelles dissociated. SAXS indicated that most of the CCP nanoclusters were fully dissociated at 83.6% decalcification. This study offers a potential to manufacture MPCs with tailored functionalities, particularly for uses in dairy applications which require the dissociation of casein micelles. [Display omitted] •Milk protein concentrate with 0–84% decalcification was obtained by ion exchange.•Soluble protein in milk protein concentrate increased with decalcification.•Casein micelle size decreased with decalcification.•Colloidal calcium phosphate dissociated from casein micelle during decalcification.•Ion exchange has potential to develop milk protein concentrate with new functions.