EXPERIMENT STATION REPORTS. 233 



4. A sample of goat's milk having a peculiar/disagreeable flavor and 

 a distinct metallic after-flavor was bronglit in recently and is now being 

 stndied. This milk came from one goat in a herd. On microscopical 

 examination the milk was found to contain an excessive amount of cellu- 

 lar debris. On plating the few samples the plate count obtained was ap- 

 proximately 5,000,000 per cc. Gelatin plates made of the sample of milk 

 became completely liquefied. Unfortunately, the cultures which were iso- 

 lated were accidentally destroyed. A second sample obtained a few 

 days later was evidently much fresher since it gave a plate count on 

 agar of only 5,000 per cc. though the cellular debris still persisted as 

 shown by microscopic examination (.3,330,000 cells per cc). This case 

 is still under study, though other work to be described later in this re- 

 port points to the probability that the metallic after-flavor is due to 

 the liquefying organisms present in the milk. 



In addition to the above work of a popular nature, a trip to Saginaw, 

 Michigan, was made at the request of the Extension department, to at- 

 tend a joint meeting of milk producers, and the Health Department of the 

 city. The object of the meeting was to consider the framing of a new 

 milk ordinance, embotlying the alternative of compulsory tuberculin 

 testing of the cattle or tlie pasteurization of the milk. During the 

 meeting the writer was called upon to give some technical advice upon 

 tuberculin testing and pasteurization. 



The research work for the year consisted in two lines of work as fol- 

 lows: (a) A brief study of the titration of culture media done in co- 

 operation with ]\[r. Fabian. This Avork, "Titration of Culture Media" 

 is reviewed briefly by Mr. Fabian in another part of this report, (b) 

 Eesearch on the Adams P'und Project lb entitled, 'The Keeping Quali- 

 ties of Butter." This work lias largely resolved itself into a study of the 

 Metallic Flavor in Daiiy Products with Special Keference to Butter. 

 This study, while not complete enough for publication at the present 

 time, has been carried far enough to warrant the statement that metallic 

 flavor in butter and other dairy products is not always due to metals 

 but may be produced by microorganisms of the peptonizing group. At 

 least two organisms have produced this flavor in butter and in milk, one 

 isolated originally from buttermilk and one from metallic flavored but- 

 ter. It is planned to study this question intensively during the pres- 

 ent year. 



The work which was done on this project by Mr. Chas. W. Brown 

 and Miss Lulu M. Smith during the years 1900 and 1010 has finally 

 been prepared for publication in a paper entitled, "A Bacteriological 

 and Biochemical Study of some Experimental Butters." This paper 

 has been submitted to the Journal of Dairy Science, (Vol. Ill, pp. 375- 

 405, 1920.) 



The following is a brief summary of the paper: Originally this in- 

 vestigation was intended as a study of tlie efl'ecis of cream ripening 

 and of pasteurization u])on the keeping qualities of butter. Owing to 

 the fact, however, that considerable time has elapsed since the work was 

 done and in this time some of the methods and ideas of manufacture 

 have undergone some changes, it is thought best lo present the results 

 from the point of view expressed in the title. 



While the purpose of ihis investigation was to study the effect of 

 ripening and pasteurization on the keeping (piality of the butter, the 



