VI PREFACE 



The science of cheese-making embraces a collection 

 of the underlying facts and principles relating to 

 the practice, arranged in systematic form so as 

 to show their relations. For example, it includes, 

 among other lines: (i) A knowledge of the con- 

 stituents of milk what each has to do in the mak- 

 ing of cheese and how each is related to the yield, 

 composition and quality of the product; (2) the 

 changes which each constituent of milk may under- 

 go and the effect of such changes upon the yield, 

 composition and quality of cheese; (3) the action of 

 micro-organisms upon the constituents of milk and 

 of cheese; (4) the effect of unorganized ferments 

 upon milk and cheese; (5) the effect of temperature, 

 humidity and other conditions upon the chemical 

 changes that take place during the operations of 

 cheese-ripening. 



While cheese has been made for thousands of 

 years, the growth of accurate, systematic knowledge 

 regarding its inner details has been extremely slow ; 

 but within the past twenty years there has been an 

 era of unprecedented activity in the investigation of 

 the chemical, biological and other problems con- 

 nected with milk and cheese. As the result of the 

 application of new knowledge thus gained, the prac- 

 tice of cheese-making has undergone marked im- 

 provements. The problems that are peculiar to the 

 manufacture of American cheddar cheese have been 

 studied extensively in the United States and Can- 

 ada, mainly under government direction in some 

 form, and more especially at agricultural experi- 

 ment stations. Two institutions have been promi- 

 nent for the extent and thoroughness of their 



