Nkw York Agricoltckal Expkkimknt Station. 171 



In 1807 Babiock & Rnssclpo aiinoimccd that the milk of ail 

 maninials coiitaius, in addition to the pi-oviously known sub- 

 stances, (jalactusc, a tryptie-like ferment capable of producing 

 digestion of casein, and tliev suggested that this substance 

 might play a considerable role in cheese ripening. The correct- 

 ness of their statements regarding the existence of this sub- 

 stance has been substantiated by Storch,ii von Freudenreich^^ 

 and •Jenseii.^'^ 



In 1901 Babcock, Russell and Vivian ^^ and Jensen ^^ almost 

 simultaneously called attention to the ability of pepsin, con- 

 tained in rennet solution, to render casein soluble, and they 

 presented experimental evidence to establish this point. 



Thus, we see that cheese, as ordinarily manufactured, contains 

 enzymes derived from three different sources, (1) bacteria, (2) 

 milk glands of cows and (3) rennet. 



Enzymes, in acting upon casein, cause its decomposition and 

 probably produce compounds that furnish some of the cheese 

 flavors. While we appreciate as highly important, from a 

 practical standpoint, the study of cheese flavors, we have 

 devoted our time chiefly to a study of enzyme action upon cheese- 

 casein. It seems that this donstitutcs so fundamental a prob- 

 lem in cheese ripening that it should be first studied, and more- 

 over its solution will doubtless go far toward solving the 

 problem of flavors. 



III. METHODS OF CHEMICAL ANALYSIS USED. 



In a later bulletin the methods of chemical analvsis used in 

 determining the amounts of nitrogen present in different forms 

 in cheese will be presented and discussed in full detail. In this 

 connection it seems suftieieut to present only a brief outline of 

 such methods. 



"Babcoek and Russell Auu. Rc^'pt. Wis. E.xp. Sta. 14:101 (1897). 



"Storcli. 40 Rept. Copenhagen Exp. Sta. (Denmark). 



"v. Freiulenreioh. Cent. f. Bak., II Abt., 5:241 (1899). 



"Jensen. See footnote 9. 



"Babcock. Russell and Vivian. Ann. Rept. Wis. Exp. Sta. 17:102 (1900>, 

 also Cent. f. Bak.. II Abt., G:817 (1900). 



'■Jensen. I.andw. Jaliib. d. Seliweiz., 14:197 (1900), also Cent. f. Bak., 

 II Abt., 6:734 (1900). 



