THE CHEMISTRY OF CHEESE MAKING 97 



followed by a corresponding increase in the fat con- 

 tent of the cheese. It was formerly believed that 

 milk of high fat content could not be economically 

 made into cheese and that only a certain percent- 

 age of the fat in milk could be recovered in cheese 

 making. Experiments have shown this idea to have 

 been incorrect. 



90. Curing of Cheese. — New cheese is lacking in 

 flavor and digestibility. By allowing the cheese to 

 undergo the ripening or curing process, desirable 

 flavors are developed, and the casein is changed into 

 a more soluble and easily digested form. The cheese 

 was formerly placed in a curing room at a tempera- 

 ture of (15° (o 70°. The curing room was kept at an 

 even temperature and the moisture content of the air 

 controlled as far as possible. During recent years, 

 however, there has been a tendency to cure cheese at 

 a lower temperature. At one time it was believed 

 that the rennet used in making cheese was the chief 

 agent in ripening or curing, and it was held that a 

 temperature of from 65° to 70° F. was the most suit- 

 able for the action of the rennet ferments. Investi- 

 gations liy Babeoek, Russell, Van Slyke, and others 

 have shown that the soluble ferments or enzymes, 

 which are normal products of all normal milk, can 

 be utilized as the chief factors in the ripening of 

 cheese, and that it is possible to ripen cheese inde- 

 pendent of the rennet ferments. 



There are two classes of ferments — the organized 

 or insoluble ferments, and the soluble or chemical 



