
~ { 
_ slight film and the whey commences to separate freely from the 

EO EIRAC ROR Nm cS Bis 

226 Re si OF THE CHEMIST OF THE 
mine, but the skilled cheseeaiaker appears to acquire a sort Onn 
intuition, as a result of long training in close observation, which 
enables him to tell the proper point. Tie object of ripening the 
milk before adding the rennet is probably to render the action of 
the rennet more rapid. Doubtless, ripening has some other 
influence, the bacteria thus added in the form of a “starter” tend- 
ing to develop more quickly in the cheese a higher flavor, as in the 
case of ripening cream for making butter. In reality, we do not 
yet understand at all satisfactorily exactly what influence the 
ripening of milk has upon the process of cheese-making or upon 
the finished product. | 
(2) Addition of rennet When the milk has been held at 
about 85° F. until properly ripened, a solution prepared from ren- 
net is added in certain proportions according to the quantity of 
milk used. The action of the rennet is, as previously stated, to 
solidify or coagulate the casein of the milk. In solidifying, the 
casein of the milk entangles and holds fast, mechanically, a large 
proportion of the fat of-the milk, and, also, more or less of the 
ash and sugar of the milk. The rennet may cause the milk, if 
properly ripened, to coagulate in ten to twenty minutes; while, if 
added to milk that has not been ripened, the rennet may not 
cause proper thickening of the milk short of two hours. 
(3.) Cutting the curd.— Again the trained judgment of the 
cheese-maker must be called into action in order to determine 
when the curd is firm enough to cut and yet not toofirm. In the 
experiments described in this report, the milk thickened enough 
for cutting in about fifteen or twenty minutes after the rennet was 
added. For cutting curd, knives containing several blades, 
about half an inch apart, are used. The curd, when cut, is left 
in small cubes, each not more than half an inch in diameter. 
The main loss of fat probably takes place in the process of cut- 
ting and of handling immediately following. The fat globules 
on the exposed surfaces of each small piece of curd are easily 
detached, and hence in cutting and in subsequent handling any 
undue mangling or violence increases the amount of fat lost. 
(4.) Stirring and heating the curd.— As soon as the curd is com- 
pletely cut, it is stirred very gently for ten or fifteen minutes, 
until the outside of the pieces of curd show the appearance of a 

