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Characterisation of milk protein adsorption onto hydroxyapatite

Tercinier, Lucile, Ye, Aiqian, Anema, Skelte, Singh, Anne, Singh, Harjinder
International dairy journal 2017 v.66 pp. 27-33
adsorption, alphaS-casein, beta-casein, beta-lactoglobulin, hydroxyapatite, kappa-casein, lactalbumin, sorption isotherms, whey protein, zeta potential
Adsorption behaviour of αS-casein, β-casein, κ-casein, β-lactoglobulin and α-lactalbumin on hydroxyapatite (HA) was characterised by determination of adsorbed protein levels and surface charge of HA. Individually, the proteins were able to bind onto HA causing a decrease in the zeta-potential magnitude of the HA particles. The maximum amount of protein that could bind onto HA and the affinity of the proteins for HA were quantified using a Langmuir model, and were different between the different proteins. αS-Casein and β-casein could bind to higher levels onto HA and had a higher affinity for HA, probably because of the presence of clusters of phosphoserine residues in their primary structures. β-Casein was also able to displace adsorbed β-lactoglobulin from the HA surface when added in a suspension of β-lactoglobulin-covered particles, probably because the affinity of the casein phosphoserine residues for HA was stronger than that of the carboxyl groups of the whey protein.