SOM ELORPSTHE COMPOUNDS. PRESSE NG: 
IN AMERICAN CHEDDAR CHEESES 

L. L. VAN SLYKE AND E. B. Hart. 

SUMMARY. 
1. Very little systematic work has been done in ascertaining 
the different compounds formed in cheese during the process of 
ripening. Such work must be done before we can understand 
the details of the process of cheese-ripening. This bulletin 
contains the first results of an extended systematic investiga- 
tion in this field of work. 
2. Paranuclein or pseudonuclein is a compound soluble in 
water but completely precipitated by 0.2 per ct. hydrochloric 
acid. It has been found in all cheeses examined by us. 
3. In a cheese 414 months old there were found the three basic 
products, lysatine, histidine and lysine. 
4. In a cheese 15 months old there were found tetramethylene- 
diamine (putrescine) and lysine. 
5. Later we may find that these or similar products are 
responsible, to some extent, for the flavors of cheese. 
INTRODUCTION. 
As cheese ages or ripens, the nitrogen compounds present in 
the fresh cheese undergo change in composition more or less 
profound in character. To the general process that embraces 
these and other changes is applied the term “ cheese-ripening.” 
In a thorough study of the cheese-ripening process, it is of 
fundamental importance that we ascertain what specific com- 
pounds are formed. We must possess such knowledge before we 
can understand fully in what way different conditions affect the 
*A reprint of Bulletin No. 219. 
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