Alkaline pH does not disrupt re-assembled casein micelles

Characteristics of re-assembled casein micelles were investigated over a broad pH range from 6.35 to 11.4. Turbidity of casein solution decreased as pH increased. The higher the pH, the lower was the turbidity value. This decrease in turbidity was concomitant with the increased diameter of micelles which is attributed to the increased electrostatic repulsion amongst casein molecules and the solvent quality of serum phase. It is hypothesised that looser expanded structure of casein micelles with smaller specific surface area available for light scattering led to a decrease in the observed turbidity of casein solutions with increasing pH. Swelling of re-assembled casein micelles at higher pH values increased the consistency coefficient of casein solutions, indicating an increase in their apparent viscosity.