Condensed Milk and Milk Powder 



95 



rapidly and there is no danger of the formation of air pockets be- 

 tween the cans. Since the heat is applied by steam under pressure 

 the temperature of the water is equal to that of the steam in the 

 sterilizer. This precaution is especially necessary in the case of 

 baby-size cans (eight ounces) which are usually piled in stacks more 

 than two deep. When sterilizing in the absence of water there is 

 danger of lack of uniformity of the amount of heat they receive. 



Temperature and Time of Exposure. — When the sterilizer is 

 filled with the cans and closed, the frame work is set in motion and 

 steam is turned into the sterilizer. In order to hasten the heating 

 and expel all the air, the exhaust and safety should be left open 

 until the temperature has risen to 212 degrees F. This temperature 

 is usually reached in about ten to fifteen minutes. The exhaust and 

 safety are then closed. 



From this point on, the process must depend on locality, season 

 of year and condition, properties and concentration of the milk. No 

 formula can be laid down which can be depended on to give uniformly 



satisfactory results under 

 all conditions. The tem- 

 perature should be high 

 enough and the duration of 

 exposure long enough to 

 insure absolute sterility of 

 the product and to give the 

 milk sufficient body to pre- 

 vent the separation of the 

 butter fat in subsequent 

 storage. The temperature 

 should not be so high nor 

 the duration of exposure 

 so long, as to cause the 

 formation of a hard, unshakable curd and dark color. 



Some processors use a very short process with high tempera- 

 tures, others raise the heat gradually and not to quite so high a 

 degree. The more gradual heating is preferable, as it gives the 

 product a better body and more viscosity, which is necessary to keep 

 the fat from separating in storage. The author's judgment in this 

 matter is, that it is not safe to raise the temperature to less than 230 



Fig:. 44. Temperature control gauge 

 Courtesy of C. J. Tagliabue Mfg. Co. 



