resulting in a reduction in both the net negative charge and steric repulsion. In the second stage rennet-altered micelles become susceptible to aggregation. This process involves Ca bridges formation, van der Waals forces, and hydrophobic interactions. Destabilized micelles will aggregate only in presence of free Ca2+. Rennet acts on casein at temperatures as low as 0C, but milk does not clot below 18C while aggregation is very rapid at high temperature (55C).The stability of the casein micelles of milk is attributed to their negative charge and to steric repulsion by the so-called hairs, calcium-induced interactions between protein molecules, hydrogen bonding and electrostatic and hydrophobic interactions. The release of CMP (which diffuses away from the micelles leads to decrease zeta potential which reduces electrostatic repulsions between rennet-altered micelles and loss of steric stabilization (removal of hairs).