650 



CASEIN VISCOSITY STUDIES 



These two experiments are typical of what we can expect of the 

 effect of heat upon casein as affecting its viscosity. The results at 



Fig. 5. Viscosity-pH curves of heated and unhealed caseins. 



first seem to be contradictory. But in the light of viscosity data 

 obtained with milk the results of Experiment 2 show that the decreased 

 viscosity by pasteurizing can be entirely accounted for through the 

 decreased pH of the solutions, provided that we ignore the effect of 

 heat on the coaguable proteins and casein. In milk, pasteurization 

 generally causes a drop in pH of 0.10 to 0.20 and a drop in viscosity 



