160 CANADIAN DAIRYING, 



Rennet acts most quickly on milk when it is at a 

 temperature near that of the animal body (98 degrees 

 R). Its action is destroyed if heated to about 15^5 

 degrees R, and is very much weakened if heated to 

 140 degrees F. It is said to coagulate the milk of 

 young animals more quickly than that of old animals. 

 Rennet action, as to time, depends upon the acidity 

 of milk, the temperature of the milk, the strength of 

 the rennet, the proportion of the rennet to the milk, 

 and the temperature of the water used for diluting 

 the rennet. The greater the acidity of the milk up to 

 .2 to .3 per cent., the higher the temperature of the 

 milk up to about 100 degrees R, the stronger and the 

 greater the proportion of rennet ; and the warmer the 

 water up to 100 degrees F., the less the time required 

 for coagulation. In order to secure as complete a 

 coagulation of the milk as possible it is desirable to 

 have it take place as rapidly as consistent with good 

 work in the after stages of cheesemaking. If coagu- 

 lation takes place too rapidly the curd cannot be cut 

 so well, nor can it be properly cooked, hence in prac- 

 tice it is customary to retard it to some extent by not 

 ripening the milk too much, and by using temperatures 

 and quantities of rennet which give an opportunity to 

 carry on the after processes in a more satisfactory 

 manner. Instead of using warm water to dilute the 

 rennet it is better to use cold water. Instead of 98 

 degrees, 86 is a better temperature for renneting milk. 

 From 86 to 95 degrees, each increase of I degree in 

 temperature of the milk decreases the time required 

 for coagulation by about one minute. From 86 to 80 



