PASTEURIZATION OF MILK AND CREAM 4]\ 
as well as the acid bacteria, it is far better not to heat 
it at all. 
Pasteurization should be condemned where its only ob- 
ject is to keep milk sweet. Its real object should be to 
destroy all actively growing bacteria and especially all 
disease-producing organisms such as the tubercle bacillus 
which is among the most resistant. 
The “Held” Process. In view of the large amount 
of data bearing upon the inefficiency of the “flash” process 
in pasteurizing milk, the wise milk dealer will equip 
himself with machinery by which milk can be held at 
a temperature of 145° \F. for 30 minutes or longer. 
There is no longer any question that to render milk safe 
from pathogenic bacteria it is necessary to employ the 
held or “holding” process of pasteurization. By this 
process all milk can be uniformly heated and held at 
the proper temperature long enough to insure the de- 
struction of all bacteria except those in a spore condi- 
tion. Fortunately the common pathogenic bacteria are 
not spore-bearing and hence are easily destroyed by this 
method of pasteurization. 
For general arrangement of machinery for pasteur- 
izing milk by “held” process, see Fig. 69, page 322. 
New York and Chicago Pasteurizing Regulations: 
In order to secure greater efficiency in pasteurizing milk, 
a number of cities have adopted ordinances making it 
necessary for milk dealers to heat milk to certain mini- 
mum temperatures. Thus New York City imposes the 
following restrictions with reference to temperature and 
time of exposure: 
No less than 158 degrees F. for at least 3 minutes. 
No less than 155 degrees F. for at least 5 minutes. 
No less than 152 degrees F. for at least 10 minutes. 
