168 TWENTY-FIFTH ANNIVERSARY REPORT. 
During the past six or seven years, the work has been directed 
along such lines of study as enzyms in cheese ;§ the relation to ched- 
dar cheese of the action of acids upon casein and paracasein ;? some 
of the compounds present in American cheddar cheese ;”° the relation 
of carbon dioxide to proteolysis in the ripening of cheddar cheese ;#4 
experiments in curing cheese at different temperatures ; conditions 
affecting chemical changes in cheese-ripening ;'* some of the first 
chemical changes in cheddar cheese ;* chemical studies of camem- 
bercecicese:) 
There have been published since October, 1891, up to June, 1907, 
thirty-three bulletins treating various phases of the subject of 
American cheddar cheese and aggregating over 1,400 pages. 
The general subject will be treated under the following divisions: 
1. The composition of cows’ milk in relation to yield, composi- 
tion and quality of cheddar cheese. 
2. The composition of whey and of cheese. 
- 3. The conditions of manufacture of cheese in relation to yield 
and quality of cheese. 
4. Method of paying for milk for cheese-making. 
5. Curing of cheddar cheese. 
6. Action of acids on casein and paracasein. 
7. Changes in cheese in early stages of manufacture. 
8. Enzyms in cheese-making and cheese-ripening. 
I. THE COMPOSITION OF COW’S MILK IN RELATION TO YIELD, 
COMPOSITION AND QUALITY OF CHEDDAR CHEESE. 
Previous to the time when this Station undertook its extensive 
investigation of cheese, dairy literature furnished very little infor- 
mation in regard to such fundamental questions as the relation of 
fat and casein in milk to yield, composition and quality of cheese,— 
the character and extent of losses of milk constituents in cheese- 
making, their causes, remedies, etc. Attention had previously -been 
given almost wholly to mere methods of cheese-making. 
*Buls. 203 and 233. 
* Buls=214,2237, 20tuand «bech.-bul 3: 
’ Bul- 210. 
ae Dill 235. 
mel sarily od 
Sei. 230) 
s Tech<Bule 4. 
SLPeCH. 2 Ot ws: 
