62 • CLEAN MILK 



immediately it is made. Fresh separated cream is much more 

 readily churned than gravity cream. 



Cheese is made from the curd (casein or cheesy portion) of 

 milk obtained by souring milk or by curdling it with rennet, chiefly 

 by the latter method. The whey is removed in different ways. In 

 soft cheese, as Brie or Camembert, the whey is merely permitted 

 to drain naturally from the curd. The whey being not all removed, 

 soft cheeses keep poorly. 



In the case of hard cheeses, the curd is cut up, and sometimes 

 heated to no° F. to toughen it, and pressed for days. Both soft 

 and hard cheeses must ripen, which process takes days or months. 

 The lactic acid germs are those chiefly instrumental in ripening 

 hard cheeses, while molds and miscellaneous germs ripen the soft 

 cheeses. In ripening, the various flavors characteristic of the special 

 cheese are developed through the action of chemical products formed 

 by the growth of these vegetable parasites or germs. In addition, 

 the cheese becomes softened, and therefore easier of digestion 

 through the action of a ferment natural to milk, resembling rennet, 

 the latter being a secretion of the animal stomach. 



How important is the influence of special varieties of germs 

 in the successful making of cheese may be appreciated from the fact 

 that it is a practice to smear shelves and walls of new factories with 

 fresh cheese (as Brie and Limburger) to convey to them the special 

 germs necessary to produce the flavor and characteristics of the 

 cheeses which it is desired to make. A starter is often added to 

 milk from which American cheese is to be made. As in the case of 

 cream for butter, the addition of the lactic acid germs tends to crowd 

 out miscellaneous and undesirable germs and give a more certainly 

 uniform product. The commercial starters are most reliable for the 

 ripening of cheese, as for butter. As a general practice, milk can- 

 not be pasteurized to kill the undesirable germs before adding the 

 starter, when cheese is to be made, because heating the milk de- 

 stroys the ferment in it which assists in ripening cheese, and heated 



