BACTERIOLOGICAL ANALYSES 661 



and therefore cannot be avoided through a study of the bacterial 

 flora of the product or the equipment, nor through the inauguration 

 of precautions which minimize bacteriological contamination, while 

 others are known to be of bacterial origin and in the latter type of 

 cases bacteriological counts may lead to channels through which 

 permanent solution may be made possible. 



As a whole the direct benefit of bacteriological work in the 

 creamery is very limited, but such work may be of value indirectly 

 inasmuch as the results are an index, within reasonable limitations, 

 of the thoroughness with which some of the more important work 

 relating to quality is performed. 



While it is obviously beyond the province of this volume to give 

 detailed directions in the technique of bacteriological analyses, in the 

 preparation of culture media and in microscopic study of bacteriolog- 

 ical preparations, for all of which the reader is referred to Manuals 

 on Bacteriology, it is deemed advisable to here offer some sugges- 

 tions relating to these special products, that may serve for the 

 guidance of those who are interested in a bacteriological study of 

 creamery problems. 



Sampling. Samples of milk, skim milk, cream and similar 

 products are best taken into small sterile glass jars with screw top 

 lined with cork or similar material, or in small sterile glass-stop- 

 pered bottles. The liquid from which the sample is taken must be 

 thoroughly mixed and the dipper or tube with which the sample is 

 taken must be perfectly sterile, otherwise the results are not depend- 

 able. About 10 cc. is usually sufficient. 



In the case of butter the sample may be placed into a sterile 

 petri dish or in a sterile bottle as in the case of milk. This is most 

 conveniently done with a sterile trier, the surface of the plug being 

 removed and a segment from one to two inches in length is trans- 

 ferred with a sterile knife or spatula to the petri dish or bottle. 



All samples should be analyzed as soon as possible. If this can- 

 not be done immediately the receptacles containing them should be 

 placed on ice or otherwise kept at a temperature as near 32 F. as 

 possible. Especially, milk and cream samples should be immedi- 

 ately cooled to 35 F. or below and kept at that temperature until 

 needed. 



