Rennet Coagulation of Casein Micelles and Heated Casein Micelles:  Importance of Steric Stabilization after κ-Casein Proteolysis

The kinetics of aggregation of para-casein micelles (pCM) and of heated para-casein micelles (HpCM) were studied and compared by estimating the initial rate of aggregation from the initial rate of turbidity increase. Aggregation of both pCM and HpCM suspensions appeared as cases of slow Brownian flocculation, with a steric contribution to the suspension's stability which could explain their aggregation behavior, including the presence of the Berridge effect at low temperatures. Glycerol addition to the medium, besides the reduction in aggregation rate by increase of medium viscosity, produced an initial aggregation rate increase, probably by interaction with the proteins of the micelle external layer. The differences observed between pCM and HpCM aggregation rate could be related to the changes introduced by high heating in the surface structure of the micelles.