While the aggregates can explain much of the protein fouling found in milk processing, this does not account for it all.  A third type of fouling has been discovered that is explained by the chemical interactions of the denatured β-lg proteins.
β-lg contains 5 cysteine residues, four of which are covalently bonded to each other, forming an S-S bond.  When β-lg is denatured, the fifth cysteine residue is exposed to the water. This residue then bonds to other β-lg proteins, including those already adsorbed to the surface. This produces a strong interaction between the denatured proteins and the surface of the container.