Ripening the Milk. 169 
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 reunet to putting the cheese in 
press, will take not more than six hours. This will 
be indicated by a rennet test of 2’4 spaces on the 
Marschall apparatus, or a rennet test of one minute 
on the Monrad test, when 5 ec. ¢. 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 
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