24 BULLETIN 1344, U. S. DEPARTMENT OF AGRICULTURE 
Milk cooled in tank or vat pasteurizers from 145° to 50° F. showed 
a poor cream volume. Cooling milk in the tank or vat from 145° F. 
to 110° or 120°, and then cooling quickly to below 50° F. over a 
separate cooler resulted in a good cream volume. 
The tests showed that cooling milk to a low temperature after 
pasteurization is necessary in order to obtain a good cream volume. 
Pasteurized milk cooled to below 45° F. showed a much better cream 
volume than that cooled to only 50° F. or above. 
Milk stored at 38° to 48° F. showed a much better cream volume 
than that stored at temperatures above 50° F. The difference in 
favor of the colder storage temperature was more marked in the 
case of the raw milk than in that of the pasteurized milk. The im- 
portance of low-storage temperatures is often overlooked at milk 
plants. 
The cream volume of milk pasteurized at temperatures from 143° 
to 145° F. was greater after two or three hours' storage at low tem- 
peratures than in the original raw milk. This gradually decreased 
as the storage period was prolonged. 
The recreaming of raw milk decreased the cream volume, but 
after one recreaming the age of the milk was of more importance 
than the number of times it was recreamed. 
The recreaming of pasteurized milk had a detrimental effect on 
the cream volume. This has a practical significance at plants which 
bottle pasteurized milk after it has been allowed to cream. 
Pumping milk at temperatures between 60° and 120° F. reduced 
the cream volume to a slight extent in some cases. Pumping raw 
milk below 60° F. and pumping pasteurized milk at temperatures 
between 120° and 145° F. with the four types of pumps used had 
practically no effect on the cream volume. 
Allowing milk to stand or to be agitated for 15 miriutes or more 
at temperatures between 60° and 110° F. had generally a detri- 
mental effect on the cream volume. This was more pronounced with 
milk that was being cooled from the pasteurization temperature 
than with that which, was being heated. 
Holding or agitating milk at a temperature of 145° F. had con- 
siderablv less effect on the cream volume than at temperatures be- 
tween 60° and 110° F. 
Clarifying milk at temperatures between 60° and 65° F. had only 
a slight effect on the cream volume, though there was a considerable 
decrease when the milk was clarified at temperatures above 80° F. 
Filtering hot milk had practically no effect on the cream volume. 
It is evident that a material decrease in the cream volume of the 
finished product may result from the accumulation of slight de- 
creases brought about by various steps in the process; therefore it is 
important to minimize as much as possible the decrease in each step. 
The various shapes of bottles caused a great difference in the ap- 
parent cream volume. 
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