Casein micelles as hard spheres: limitations of the model in acidified gel formation

In many situations casein micelles can be treated as adhesive spheres and milk gels are often considered as particle gels. In this study of acidified milk gels, produced over a wide range of acidification conditions using glucono-δ-lactone as acidulant, we show that adhesive sphere and particle gel theories are of limited applicability. Internal micellar integrity and the rates of change of structure and composition with pH play a role in defining the viscoelastic properties of the resulting gels. The ongoing changes in internal micelle structure enacted as pH is lowered are discussed in terms of the recent dual-binding model for casein micelle structure and assembly.