Oct. 1, 1925 
Bacterial Count of Milk and Cream 
699 
In contrast with centrifugally separated cream, gravity separated 
cream shows a much higher percentage increase in bacterial count 
over whole milk. The low-count milk gives the greatest increase in 
bacterial count in the cream. Table 7 shows the groupings of the 
milk according to bacterial counts, together with percentage increase 
of cream over whole milk of each group. 
Table VII .—Per cent of increase in bacterial count of gravity cream over that of 
whole milk , classified by groupings of whole-milk bacterial count 
Bacterial count of whole milk 
4 
Number of 
samples 
Average 
per cent of 
increase 
Number of 
samples 
showing no 
change 
0 to 50,000......... 
15 
198.96 
0 
50,001 to 100,000......... 
3 
156.34 
0 
100,001 to 500,000..._____ 
4 
89.88 
0 
500,001 to 1,000,000........... 
3 
95.53 
0 
1 ,000,001 and over....... 
Total........j 
25 
0 
CONCLUSIONS 
Centrifugal separation with a clean separator will not result in 
cream having a greatly higher bacterial count than the whole milk 
from which the cream is obtained. 
Gravity separated cream will give a much higher bacterial count 
than the whole milk from which it comes. 
In view of the fact that gravity cream plays a very minor part in 
the market-cream trade, it would seem that those milk ordinances 
allowing cream of a certain grade with a bacterial count hundreds 
per cent greater than milk of the same grade are based upon custom 
rather than scientific investigations: High counts in market cream 
may very probably be due to a poor quality of milk used for sepa¬ 
ration and to lack of care in sterilizing equipment rather than to 
any normal causes involved in the process of separation. 
o 
