THE PASTEURIZATION OF MILK 



apparatus. From these tanks it is pumped into 

 the heating chambers. Where steam enters di- 

 rectly into the milk apparatus the same objections 

 obtain which were noticed in the description of the 

 Danish type of heater. Superheating of the milk 

 in whole or in part, an objectionable cooked taste, 

 interference with the cream line, etc., are likely to 

 follow. Where an outside heating tank is employed, 

 it is comparatively easy to keep the water at a 

 nearly uniform temperture by means of a thermo- 

 stat, which controls the introduction of steam. 

 With this heated water being pumped to the milk- 

 heating apparatus, it is certain that the milk can 

 never get above the temperature to which the water 

 is heated, and if this water is not more than 10 or 

 15 hotter than the temperature at which it is the 

 intention to heat the milk, no serious superheating 

 can result. This point will be more fully de- 

 scribed later. 



In all heaters of this type some method is em- 

 ployed to keep the milk in constant motion as it 

 flows upward between the heating surfaces, thus 

 insuring that all portions of milk come in contact 

 with their surfaces. In the machine illustrated in 

 Fig. 3 this agitation is accomplished by means of 

 52 



