STATUS OF PASTEURIZATION OF MILK 
Table 3. — Approximate quantity of 
milk Pasteurized in various cities as 
shown by returns, etc. — Continued 
City 
Popula- 
tion, 
1920 
census 
Per cent 
of milk 
Pasteur- 
ized 
Galion, Ohio -.- --- 
7,374 
7,283 
7,252 
7,201 
7,111 
7,012 
7,000 
6,967 
6,964 
6,952 
6,865 
6,788 
6,664 
6,654 
6,497 
6,456 
6,350 
6,315 
6,224 
6,164 
6,141 
6,122 
6,107 
6,103 
6,018 
6,000 
5,939 
5,900 
5,788 
5,776 
5,745 
5,476 
5,410 
5,099 
4,551 
3,924 
3,908 
3,130 
3,039 
2,405 
2,173 
2,009 
1,889 
20.0 
Kane, Pa - 
70.0 
00.0 
00.0 
50.0 
75.0 
Troy, Ohio 
St. Marys, Pa 
22.0 
00.0 
Newark, N. Y 
Hillsboro, Tex 
67.0 
00.0 
00.0 
Elkins, W. Va 
00.0 
Pontiac, 111 
75.0 
33.0 
Franklin, Mass 
00.0 
00.0 
80.0 
Great Barrington, Mass 
00.0 
60.0 
Clifton Forge, Va 
Union, S. C 
00.0 
00.0 
Pana, 111 
80.0 
25.0 
33.0 
Caribou, Me - 
00.0 
00.0 
Greenwich, Conn 
Palo Alto, Calif 
80.0 
55.0 
Bowling Green, Ky 
Bellevue, Ohio .- - - 
50.0 
100.0 
95.0 
Hillsdale, Mich 
50.0 
25.0 
10.0 
Canyon City, Colo 
67.0 
100.0 
Waseca, Minn 
50.0 
00.0 
50.0 
State College, Pa 
10.0 
Elko, Nev ._. 
25.0 
Hartsville, Ala._ 
50.0 
50.0 
The flash process consists in heating 
rapidly to the Pasteurizing tempera- 
ture, then cooling quickly. In this 
process the milk is heated from 30 
seconds to 1 minute only, usually at a 
temperature of 160° F. or above. In 
view of the previously mentioned re- 
quirements for Pasteurized milk this 
process should not be considered suit- 
able for proper Pasteurization. Most 
cities now prohibit the use of the flash 
process for the Pasteurization of milk. 
In the holder process the milk is 
heated to temperatures of from 140° 
to 150° F. and held for approximately 
30 minutes, after which it is rapidly 
cooled. Sometimes the milk, instead 
of being held at a certain temperature 
in one tank for 30 minutes, is merely 
retarded in its passage through sev- 
eral tanks or other retarding device 
so that the theoretical length of time 
required for the milk to pass through 
is about 30 minutes. In such cases, 
however, there is not always assur- 
ance that all the milk is held for the 
desired time. 
Results of studies made upon con- 
tinuous flow holders, both under actual 
commercial conditions and in the lab- 
oratory, point to the fact that careful 
qualitative bacteriological analysis of 
milk Pasteurized by this method 
sbould be made. It must be remem- 
bered that a low-count milk does not 
always mean a safe milk. If an appa- 
ratus is used which produces a low- 
count milk but which does not hold for 
30 minutes, such apparatus should 
be viewed with distrust, for the safety 
factor is not assured. In many in- 
stances, the actual flow through the 
machine does not coincide with the 
theoretical flow. The holder process 
has almost entirely replaced the flash 
process, and is the one most used in 
this country. 
The system of Pasteurization in the 
bottle was developed several years ago 
but has not come into general use. 
With this system the bottles of milk, 
usually in the cases, are placed in a 
compartment where the milk is heated 
to the desired temperature, held and 
cooled. With some types the bottles 
of milk are removed from the cases 
and pass slowly through the machine, 
being heated at the beginning and 
cooled at the end of the process. The 
heating is usually accomplished by 
passing sprays of hot water over the 
bottles. Either a special water-tight 
cap is used or the bottles are covered 
with a specially constructed pan in 
which there are small holes through 
which the hot water passes and forms 
a thin film around the bottles. 
The advantage of this process lies 
in the fact that the milk after being 
heated is not exposed until it reaches 
the consumer, thereby eliminating any 
danger of contamination through han- 
dling. 
The cost with this system is greater 
than with bulk Pasteurization. Extra 
steam and refrigeration are required, 
for it is necessary to heat and cool the 
bottles and cases in addition to the 
milk. Furthermore, extra space and 
more handling are required. This 
system is not in general use on a large 
commercial scale. 
ADVANTAGES OF LOW-TEMPERA- 
TUEE PASTEURIZATION 
In genera], the trend of Pasteuri- 
zation has been toward the holder 
process, and with this tendency the 
