HEAT-STABILITY OF HOMOGENIZED MILK - ROLE OF INTERFACIAL PROTEIN

The role of interfacial protein in determining the heat stability of r ecombined milk was investigated by removing serum protein prior to hom ogenization and reincorporating it after homogenization. In addition, the surface protein composition of recombined fat globules was probed by analyses of protein load and by quantification of the individual su rface protein components using FPLC. In the absence of serum protein, substantially more casein was bound to the fat surface during homogeni zation. Despite this, the detrimental effect of homogenization on heat stability did not occur when serum protein had been removed from the system. Reincorporation of serum protein after homogenization caused t he heat coagulation time-pH profile to revert to a form very similar t o that observed without removing serum protein from the system. Thus, adsorption of serum protein did not affect heat stability. It is more likely that heat-induced interactions of serum protein with surface-ad sorbed casein promoted heat coagulation. Fat surface area rather than casein load affected these interfacial protein-protein interactions du ring heating.