184 REPORT OF THE CHEMIST OF THE 
the few weeks required to ripen this type of cheese and may 
safely be said to be of no importance in the process. 
The bacteria also play no part in the proteolysis of the cheese. 
Their function is to change the lactose to lactic acid and thereby 
change the paracasein into a form desirable for the future action 
of the enzyms. 
It is also an established fact that the acidity of cheese is not 
due to lactic acid’ as commonly believed, but to mono-calcium- 
phosphate (CaH,P,O,) which is formed by the action of the 
lactic acid, produced by bacterial action, upon the insoluble: 
phosphates always found in fresh cheese curd. | 
The changes in the paracasein of the newly made cheese curd 
are more extensive than had hitherto been supposed, and the 
proof of another chemical change in the paracasein is established 
showing that the salt-soluble compound found by Van Slyke and 
Hart? undergoes another change which renders it insoluble again 
and that this insoluble product is the one attacked by the enzyms 
in the cheese and changed further into complex groups of water 
soluble forms.’ 

* Paper by the author read at the meeting of the Assoc. Off. Agrl. Chemists, 
Nov., 1906. “ The acidity of cheese and its determination.” 
bse cit: ; 
* For a more complete discussion of this point see Technical Bul. 4 of 
this Station. 
