CHAP. vi. RENNET. 819 



which has a good effect on the character of the cheese. In cold weather 

 this ripening is prevented by the low temperature of the milk during 

 the night, and hence it is, at all events in part, that the cheese of 

 late autumn, winter, and early spring ripens slowly, and is wanting in 

 mellowness. To obviate this, the following course was adopted by a 

 most intelligent cheesemaker, with whom we once had a long conversa- 

 tion on dairying topics, in Canada : The evening's milk, from October 

 onwards, was warmed to about 84 F., and allowed to stand three or four 

 hours, before being added to the next morning's milk ; in this way it 

 acquired the requisite mellowness, which it communicated to the fresh 

 milk of the morning, and the /result was that the cheese resembled 

 summer cheese in character 'and sold for as much money. This 

 question of ripening, indeed, in reference to both milk and cream, in 

 cheese- and butter-making respectively, is one which well merits more 

 study and investigation than it has hitherto received. 



When milk has been exposed to the air for a certain time, the 

 duration of which varies, according to the season, it becomes sour and 

 coagulates. The curd which is thus formed may then be either made 

 into butter, by the process of churning, as detailed in the preceding 

 chapter, or it may be merely broken, when the serum or whey will 

 separate from it, and, by means of pressure, be converted into cheese. 

 This curd, being composed of both the caseous and the butyraceous 

 matter, constitutes the richest, or what is commonly termed full-milk 

 or whole-milk cheese. That produced by the curd remaining after the 

 cream has been taken off is necessarily poorer in consequence of the 

 abstraction of the but} 7 raceous substance, and is termed skim-milk 

 cheese. 



It is known, however, that cheese manufactured from sour milk is 

 hard and ill-flavoured, and means have been devised to curdle it while 

 sweet. With this object various substances have been employed, but 

 the most effectual one hitherto discovered, and consequently the most 

 universally used, is taken from the stomach of calves, and denominated 

 rennet. It is the digestive ferment secreted by glands in the internal 

 lining membrane of the fourth stomach of that animal. Even after 

 the animal is dead the glands remain charged with this juice, and, if the 

 stomach is preserved from putrefaction, the fluid retains its coagulating 

 properties for a considerable period. As a matter of fact, the maw or 

 stomach of the calf is preserved by salting after careful cleaning. 

 After the maw has been salted a certain time, it may be taken out and 

 dried, and then it will retain the same property for an indefinite 

 period. A small piece of the maw thus dried is steeped overnight in 

 a few spoonfulls of warm water, and this water will coagulate the 

 milk of four or five cows. Liquid rennet is now prepared of uniform 

 strength, by those who make it a business and a study, and many 

 cheesemakers prefer the prepared article to the crude rennet-skin, a 

 given measure of it accurately coagulating a specified quantity of milk. 



Milk coagulates with all acids, but acetic and hydrochloric acids are 

 the most effective. If the dairyman has any reason to doubt the power 

 of his rennet, he may always put it thus to the test. Let him take a 



