142 EVAPORATED MILK STSRIUZING 



understand that the size of the cans may influence the sterilizing 

 efficiency. It takes more time and agitation to sterilize gallon 

 cans than small cans. At a time of the year when the milk con- 

 tains micro-organisms of relatively high resistance to heat, as 

 is often the case especially in fall and winter, the per cent loss 

 of gallon cans due to "swell heads" may become disastrously 

 large, unless the manufacturer makes a special effort to adjust 

 his process for gallon cans. Gallon size cans require about one 

 degree F. more heat on a 15 minute run of holding than tall-size 

 cans, and tall-size cans require about one degree F. more than 

 family- and baby-size cans. 



The installation and efficient use of automatic temperature 

 controllers and recorders is of material assistance for securing 

 uniform results of sterilization. These accessories are made use 

 of in numerous factories, and have proven to be 'of valuable 

 help to the manufacturer. Aside from the fact that they actu- 

 ally do facilitate the temperature control, they automatically 



Fig*. 63. Bulb for automatic temperature control 

 Courtesy of Taylor Instrument Co. 



make for increased efficiency of the operator. The knowledge 

 of the operator that his work is permanently recorded and 

 checked up exerts a beneficial effect on his performance. 



The operation of an experimental or pilot sterilizer also has 

 proven a great help in the accurate determination of the amount 

 of heat which the evaporated milk of any batch requires, to 

 produce the desired viscosity, body and color and that it will 

 stand without becoming hopelessly curdy. These machines are 

 of small size, accommodating only a few cans. 



A few sample cans of each batch are placed in the pilot 

 sterilizer and run through the process. Thus the proper process 

 to be used for the entire batch in the large sterilizer may be 

 adjusted according to the behavior of the contents of the sample 

 cans in the pilot sterilizer. 



Qualifications of the Processor. The operator, or the person 



