308 CREAMERY BUTTER MAKING 



to 150° F., and hold at this temperature for 15 minutes. 

 Then quickly cool and keep the cream as near freezing 

 temperature as possible for at least 24 hours before 

 freezing. Holding the pasteurized cream cold this length 

 of time restores to a great extent the viscosity which it 

 has lost in the pasteurizing process. 



Cream can also be satisfactorily pasteurized in con- 

 tinuous pasteurizers, but greater care is necessary because 

 of the higher temperature that must be employed. But 

 even vi^ith the higher temperature the pasteurizing is 

 bound to be less thorough than where the cream is held 

 some time at a lower temperature. 



Freezing Process. With an initial temperature of 

 about 35° F., the time required to freeze ice cream should 

 average about twelve minutes, and to get the best con- 

 sistency the temperature at the close of the freezing 

 process should be approximately 28° F. 



Too quick freezing causes the water to separate from 

 the cream, which "results in a granular ice cream. Freez- 

 ing too slowly reduces the overrun and tends to make the 

 ice cream smeary. 



To reduce the temperature of a mass of cream below 

 the freezing point, requires a freezing mixture of a low 

 temperature. Such a mixture is secured by mixing salt 

 and crushed ice in the proportion of one of salt to about 

 twelve of ice. The purpose of the salt is to lower the 

 freezing point of the melting ice and to hasten the melt- 

 ing. 



To melt one pound of ice at 32° F. into water at the 

 same temperature requires 142 heat units. Rapidly melt- 

 ing ice, therefore, absorbs a large quantity of heat which 

 jn the freezing of cream is largely extracted from the 

 cream. 



