Changes in Sodium Caseinate Heated in Various Model Systems

Sols containing 3% sodium caseinate in deionized water (heated and unheated), .02Mcalcium chloride, 5% lactose, .011Mpotassium phosphate, .01Msodium citrate, .039Msodium chloride, synthetic ultrafiltrate, and milk dialysate were heated at 100 C for 30 min.Quantitative and qualitative differences in composition were demonstrated chromatographically and electrophoretically which suggested formation of aggregates that varied with the composition of the dispersing medium.Losses ranging from 1.9 to 75, 5.5 to 71.6, 3.9 to 23.7, and .4 to 31.3% occurred in ?-,K-,/3-, and as-caseins.One aggregate appeared on heating in the presence of calcium chloride and another in the presence of calcium chloride, potassium phosphate, sodium citrate, sodium chloride, synthetic ultrafiltrate, and milk dialysate.An unresolved casein aggregate appeared in all model systems and ranged from 5.1% in the unheated control to 14.4% in sodium chloride.