Condensed Milk and Mii,k Powder 93 



CHAPTER XII 



STERILIZING 



The sealed cans are now ready for the sterilizer. If they cannot 

 be sterilized within an hour or two they should be submerged in ice 

 water or placed in a refrigerating room until the sterilizer is ready 

 for them. This precaution is especially advisable in summer. 



Purpose of Sterilization. — The chief purpose of subjecting the 

 evaporated milk to the sterilizing process is to kill all germ life and, 

 therefore, preserve the product permanently. When the hermetically 

 sealed cans come from the sealing room, their contents are not sterile. 

 The only means to preserve this milk is to subject it to temperatures 

 high enough to kill all forms of ferments, organized and unorganized, 

 vegetative cells and spores. The success of the manufacture of this 

 product depends to a large extent on the process of sterilization. 



Aside from, this, the manufacturer aims to gain another com- 

 mercially important condition, namely, to prevent the separation of 

 the butter fat. Before sterilization, there is nothing to prevent the 

 fat from separating out in the evaporated milk and from churning 

 in transportation, unless the evaporated milk was homogenized. This 

 is a highly undesirable characteristic, making the goods unmarket- 

 able. The sterilizing process helps to so change the physical proper- 

 ties of the milk, that this tendency of the fat to separate is greatly 

 minimized. The sterilizing temperatures used, further lend to the 

 evaporated milk a creamy consistency and yellowish color, giving 

 the product a semblance of richness. 



Sterilizers. — The apparatus used for sterilizing is a huge boiler- 

 like, hollow, iron cylinder or box. It opens either at one end or on 

 the side. Its interior is equipped 

 with a revolving framework, 

 steam inlet and exhaust, a water 

 distributing pipe running the en- 

 tire length of the sterilizer, and 

 a water exhaust. The sterilizer 

 carries on its exterior a steam 

 gauge, a vacuum gauge, a water 



r . , Fig. 41. Sterilizer for evaporated milk 



gauge, a blow-off valve -and a Courtesy o£ Arthur H arf is & 0. 



