124 



BACTERIOLOGICAL METHODS 



The following is a tentative standard based upon the tempera- 

 ture differential as above suggested. 



It is not practicable to fix a numerical bacterial limit for creams. 

 Tests made show that the count varies within wide limits, even in 

 cream from milk which has been kept under the most favorable 

 sanitary conditions and surroundings. Fresh creams, that is, the 

 cream removed from the milk as soon as formed, usually within 

 24 hr. after the milk is drawn, contains comparatively fewer bac- 

 teria than the cream which has been set aside to ripen. The 

 ripening process is far from objectionable, in fact it is encouraged 

 and regulated in the well-conducted dairying establishments in 

 order to develop the desirable butter flavor. Most of these 

 flavoring lactic acid bacteria are removed in the process of butter 

 making, being drawn away and worked out with the buttermilk, 

 only comparatively few remaining in the butter itself. 



Taking milk samples is not unUke water sampling. Milk 

 should be examined not later than 6 hr. after being drawn. If it 

 cannot be examined within that time it must be kept on ice but 

 in no case should the examination be made later than 1 2 hr. after 

 the milk was drawn. 



Body cell counts should not be omitted and proper judgment 

 should be exercised in interpreting the findings. Body cell counts 



' Ripened cream contains numerous lactic acid bacilli, 300,000,000 per cc, and 

 even more. 



