Effect of Single and Double Homogenization of Cream upon Coagulation by Heat and Rennet and upon Separation of the Fat

Abstract

The widespread use of the homogenizer in the processing of dairy products has made desirable a better knowledge of the physical changes which occur during homogenization. Altera- tions in the physical equilibria of the milk fat appear to be cap- able, under certain conditions, of changing the heat stability of the product fully as much as small shifts in pH or in salt balance. Consequently, a change in heat coagulation caused by a change in the distribution of the fat phase can be considered as a part of the general heat stability problem (17). The effect of homogenization upon rennet coagulation is of interest because the results obtained indicate that changes in the condition of the fat phase may be of importance in rennet action. Workers in the past have not considered the effect upon rennet Coagulation of an altered fat equilibrium such as is produced by Itomogenization. In the manufacture of sterile cream two factors are at present causing some dif/ieulty, the instability of the cream toward heat and the fat separation which occurs while in storage. A quanti- tative study has been made of the increase in heat stability which may result from rehomogenization and also of the degree of fat separation in homogenized cream during long periods of storage. Burgwald (2) found the susceptibility of cream to feathering in coffee was increased when the product was homogenized. The effect of single stage homogenization upon the heat sta- bility of clams of~brent fat percentages when temperature