Ice Cream 41 



condensed milk. Again, the percentage of fat in the 

 cream may be varied to give the ice cream the de- 

 sired percentage of fat. 



For standardization see page 31. The percen- 

 tage of fat in the mix is figured by dividing the total 

 pounds of fat by the total weight of the materials 

 in the mix. (The " mix " is the unfrozen ice cream.) 



Milk powder is either used to make milk or to 

 bring up the percentage of milk solids not fats or 

 in place of the condensed milk, or the cream or milk 

 may be made by mixing the various milk products 

 mentioned above. 



Machines for Mixing Materials. 



The mixing process can be accomplished by two 

 types of machines. One is the type in which the 

 materials are forced through very small holes or 

 slots by centrifugal force. It is known as an emulsi- 

 fier. The other, in which the material is forced be- 

 tween a valve and its seat by a piston pump, or 

 through a very small opening between porcelain 

 discs by a piston pump, is known as a viscolizer and 

 homogenizer. Viscolizers and homogenizers are 

 much more powerful than the emulsifiers and break 

 up the fat globules so finely that the cream can 

 never be rechurned. Many ice-cream makers run the 

 whole mix through these machines, which increases 

 the viscosity which in turn increases the swell. 



Mixim^. 



Opinions differ as to the correct temperature at 

 which the materials should be emulsified. Some 

 manufacturers prefer to pasteurize and then emul- 

 sify at the same temperature. A temperature of 

 120° to 130° F. is satisfactory. The materials 

 must be kept thoroughly mixed or else the fat 

 rapidly separates and comes to the top. This mix- 



