PASTEURIZING MILK. . 25 
Milk can be pasteurized by the ordinary holder system at 145° F. 
for 30 minutes. It can then be bottled hot in special oversized milk 
bottles of the ordinary type and capped with ordinary sterile caps. 
Before being filled the bottles can be steamed for two minutes by 
running the crates inverted on a conveyer over steam jets. The 
bottles would then go through the bottling machine in a hot condi- 
tion and would be practically sterile. The crates of hot bottled 
pasteurized milk can then be cooled by stacking in a refrigerator 
room and blowing cold air through the crates. In the cold season 
outside air can be used for cooling, and in the warm season re- 
frigerated air can be circulated through the crates. 
This process can be modified. The hot milk can be held in the 
bottles at 145° F. instead of in a tank, and the crates of hot pasteur- 
ized milk can be cooled by spraying with cold water instead of air. 
From the results of experiments with air cooling on a small prac- 
tical scale started in 1913, it is believed to be entirely practical to 
cool hot bottled milk by means of forced- air draft. The results of 
this work are being prepared for publication in the near future. 
Since the process of bottling hot pasteurized milk has not as yet 
been worked out for practical use, it is impossible to state definitely 
all its advantages and disadvantages. However, from laboratory 
experiments alone certain advantages are plainly shown. From a 
sanitary standpoint one great advantage of the process of bottling 
hot pasteurized milk in hot bottles lies in the fact that bottle infec- 
tion is eliminated. From a commercial standpoint there is also an 
advantage, because of the reduction of milk losses on the cooler 
caused by adherence of milk and by evaporation. Ordinary card- 
board caps may be used in this system, since they do not have to be 
water-tight, which is obviously a point of great advantage so far 
as cost is concerned. « 
At the present stage of this work it is impossible to state how the 
cost of air cooling will compare with the ordinary methods in prac- 
tice, but it is believed that there will be no more expense involved. 
The length of time required for cooling is perhaps the greatest 
disadvantage of this process, and yet this would be of no consequence 
except in plants where the milk is delivered immediately after 
pasteurization. In the majority of milk plants the milk is pasteur- 
ized in the morning or afternoon, placed in refrigerators, and deliv- 
ered early the next morning. Consequently in most plants it would 
make little difference whether the cooling process was performed 
quickly or slowly. 
SUMMARY. 
1. The process of pasteurization in the bottle, using a temperature 
of 145° F. for 30 minutes, causes satisfactory bacterial reductions. 
