Ripening the Milk 245 



fluid the stream is continuous, but as soon as the ren- 

 net takes effect and a clot is formed, the stream stops, 

 and no more escapes. The number of spaces of milk 

 which escape is taken as the measure of the ripeness 

 of the milk. When the percentage of lactic acid is 

 great the stream stops sooner than where little acid 

 has been formed, so that in the ripe milk a less 

 number of spaces shows upon the side of the vessel 

 than in the unripe milk. 



Degree of ripeness necessary. By ripeness of milk 

 for cheese making is meant, as in the case of but- 

 ter making, the degree of lactic acid development that 

 has taken place. For cheese making, the develop- 

 ment of lactic acid should not have proceeded so 

 far that the milk is distinctly sour to the taste, and 

 it should have proceeded far enough so that the 

 whole process of cheddar cheese making, from the 

 time of adding the rennet to putting the cheese in 

 press, will take not more than six hours. This will 

 be indicated by a rennet test of 2% spaces on the 

 Marschall apparatus, or a rennet test of one minute 

 on the Monrad test, when 5 c. c. of diluted com- 

 mercial rennet extract (1 part rennet to 9 of water) 

 are added to 200 c. c. of milk. 



Starters. In very many cases the milk, when 

 brought to the factory, will not be sufficiently ripe 

 to give the tests indicated above. In that case it 

 should be allowed to ripen before the cheese making 

 process begins. This may be brought about by 

 heating the milk up to 85 F., when the germs 

 already present become more active ; but the time 



