METHODS COMMONLY USED IN HEATING MILK 295 



both in attaining the maximum temperature and the period over 

 which the milk is maintained at this temperature vary within 

 wide limits. But the term ' pasteurisation ' appears to be applied 

 very generally to them all, and at the present day appears merely 

 to imply that the milk has been heated to a temperature which 

 probably has not reached that of the boiling-point of water and 

 that it has been subsequently rapidly cooled. 



The use of the lower temperatures (140-170 F.) is mainly 

 commercial and hardly employed in the preparation of infants' food 

 in the home. 



.-c 



Apparatus for home pasteurisation. The carrier with 

 bottles, when in position, rests with the upper disc 

 of the carrier on the supports C in the vessel. 



The term is, however, frequently applied to the domestic pre- 

 paration of food for infants. 



Where pasteurisation is concerned two points should be men- 

 tioned : (a) The maximum temperature to which the milk is 

 raised, and (b) the length of time the maximum temperature is 

 maintained. It is rare, however, except in the literature dealing 

 with the commercial pasteurisation of milk, to find any mention 

 of these items, although the maximum temperature reached is 

 sometimes given. 



Home Pasteurisation. It is usual in home pasteurisation to 

 employ some form of apparatus of the type shown in the figure above. 

 Modifications will evidently be found in the number of bottles and 

 in the shape of the bottle, the form of the carrier holding the bottles, 



