214 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
find that a temperature of 145° F. (62.8° C.) for 30 to 
45 minutes, under commercial conditions, will destroy 
the pathogenic bacteria which are most likely to occur 
in milk, with the possible exception of tubercle bacilli, 
and it appears probable that this organism will also be 
destroyed, although it would be desirable to have more 
definite information on this point. Exposure to heat 
to this extent, however, cannot be depended upon to 
destroy all of the toxins and the decomposition products 
which may be present in milk as a result of bacterial 
growth, while, at the same time, it destroys the antiscor- 
butic properties of milk. Moreover, it is not certain 
that it does not decrease the digestibility of milk. 
METHODS OF PASTEURIZATION 
There are three methods of pasteurization: 
1. The “flash” or continuous process, in which the 
milk flows continuously and is exposed to a heated sur- 
face for a few seconds. 
2. The “holder” process, in which the milk is heated 
to a certain temperature and is then held at that tem- 
perature for a certain period. 
3. Pasteurization in the Final Container.—In this 
method, the raw milk is placed in the bottle in which it 
is to be delivered, the bottle is capped, and the filled 
bottle is then exposed to the desired degree of heat. 
The “flash” process is less reliable than the “holder” 
method, as not all of the milk is certain to be heated to 
the temperature registered by the thermometer; some 
may be heated in excess of the temperature intended and 
thus balance any deficiency of temperature in the milk 
which may not be heated to the desired temperature. 
Furthermore, a higher degree of heat is required to de- 
