564 HEAi/THtfuivNEss OF BUTTER 



Mohler, Washburn and Rogers 1 further state that constant 

 storage in an icy temperature does not destroy the virulence of 

 butter which contains dangerous tubercle bacilli and that no de- 

 pendence should be placed on the action of the salt that is added 

 to butter, as an agent in the destruction of tubercle bacilli, the 

 action being very slight at best. The bacilli retained virulence in 

 salted butter for six months. 



The findings quoted in the preceding paragraphs show con- 

 siderable variations in the length of time butter infected with 

 Bacillus tuberculosis retains virulent bacilli. However, this 

 evidence shows conclusively that butter made from tubercle-in- 

 fected milk or cream harbors these bacilli and is capable of 

 spreading the disease. It further shows that neither does the 

 separation of the milk by centrifugal force insure freedom of 

 these bacilli in the cream nor does the salt in butter destroy 

 their virulence. 



Fortunately the tubercle bacilli, as well as the germs and 

 viruses of other common milk-borne diseases infectious to man, 

 such as those of foot and mouth disease, typhoid fever, diphtheria, 

 scarlatina, dysentery, septic sore throat, are readily destroyed 

 by pasteurization of the milk or cream and all butter made from 

 properly pasteurized milk or cream may safely be considered 

 free from the germs or viruses of these diseases. Thus Rosenau 2 

 as the result of his own extensive investigations, and summariz- 

 ing the work of other investigators of acknowledged authority 

 states that it is justifiable to assume that ordinary market milk 

 pasteurized by heating to 60 C. (140 F.) for 20 minutes, would 

 be safe for human use by mouth so far as tubercle bacilli are 

 concerned, that the virus of foot and mouth disease is killed 

 with certainty at a temperature of 60 C. for twenty minutes, 

 that milk heated to 60 C. for two minutes destroys the typhoid 

 fever germs, that the diphtheria bacillus and the cholera vibrio 

 "die at comparatively low temperatures (55 to 60 C.), that the 

 dysentery bacillus is killed at 60 C. in ten minutes, that the 

 infective principle of Malta fever, M. Melitensis, is destroyed at 

 60 C. and that a temperature of 60 C. for twenty minutes is 



1 Mohler, Washburn and Rogers, The Viability of Tubercle Bacilli in 

 Butter. U. S. Dept. of Agr. B. A, I. Twentieth Annual Report, 1909, 

 pp. 179-185. 



2 Rosenau, The Milk Question, 1912. 





