It is a well known fact that milk varies greatly in quality. Some of it will make butter of the highest quality, some again, owing to injurious organisms, will not make prime butter. The injurious fermentations are much worse at times than at others. Milk as it is received at the creamery, is often “off” in odor. It is, therefore, desirable to know what patron is responsible for this tainted milk. It was supposed by patrons that these odors had their origin in weeds, etc.
Some years ago Mr. Monrad gave, at one of the meetings of the Iowa State Dairy Association, a simple test for detecting these odors which is largely used in European dairies. Samples of milk from different patrons are placed in glass tubes and then allowed to stand for a day or less, in a warm place to allow the bacteria to develop. The odors and gaseous fermentations may easily be detected.
Pammel, L. H. and Mead, I. J.
"Notes on dairy bacteriology.,"
Bulletin: Vol. 3
, Article 4.
Available at: https://lib.dr.iastate.edu/bulletin/vol3/iss34/4