170 THE BOOK OF BUTTER 



commonly accepted understanding of the term, is simply 

 oxidation." Rahn, Brown, and Smith 1 write, "Butter 

 is said to be rancid if it has an undesirable taste or smell, 

 due to an aged condition, that cannot be described defi- 

 nitely by other terms." 



In contrast to these definitions are the following state- 

 ments from two butter judges. According to White : 2 

 11 If the student is given some stale tallow and told that 

 it is rancid and then is given some stale lard and told that 

 it is also rancid, he will be able to distinguish that the 

 smell is not the same. If he is then given some butter 

 which has developed a butyric acid odor he will find still 

 a different odor, and the question would naturally be asked 

 which of the three is and should be defined as rancid. 

 If the odors found in the tallow and lard are rightly defined 

 as rancid, then the butyric acid odor in butter known by 

 all butter judges, commission men, butter buyers, butter 

 makers and dealers in general, should be called something 

 else, as they are not the same ; though that found in butter 

 may be called rancid as a general term, meaning stale, 

 but specifically it perhaps should be called butyric odor. 

 The butyric odor gradually passes off since it is volatile, but 

 there will then still remain a stale odor and this will smell 

 like stale tallow. On the other hand, if the butyric acid odor 

 is the true rancid odor, then the odors found in the other 

 fats and oils should not be defined as rancid." Keiffer 3 



1 Rahn, Otto, Brown, C. W., and Smith, L. M., Keeping Qual- 

 ities of Butter, Mich. Agri. Exp. Sta., Tech. Bui. 2, 1909. 



2 White, B. D., Rancidity, Letter to the author, 1910. 

 (White was formerly in charge of butter investigations, U. S. 

 Dept. of Agri., B. A. I.) 



3 Keiffer, P. H., Rancidity, Letter to the author, 1910. 

 (Keiffer is the president of the Gude Bros. Keiffer Co., butter 

 merchants in New York City.) 



