66 THE BOOK OF CHEESE 



hence should be avoided. A sour cheese shows lack of 

 skill and care on the part of the cheese-maker. 



Conditions canning an acidy or sour cheese: 



Receiving sour or high acid milk at the cheese -factory. 



Use of too much starter. 



Ripening the milk too much before the rennet is added. 



Removing the whey before the curd is properly firmed, 

 hence leaving it with too much moisture. 



Development of too much acid in the whey before the 

 whey is removed. 



Improper relationship between the moisture and acidity 

 at the time of removing the whey. 



Conditions causing deficient acid: 



Adding the rennet before sufficient acid has developed. 



Not using sufficient starter. 



Not developing sufficient acid in the whey. 



86. Acidity and rennet action. The rennet extract 

 acts only in an acid medium. The greater the acid de- 

 velopment, within certain limits, the faster the action of 

 the rennet. If enough acid has developed to cause a 

 coagulation of the casein, the rennet will not coagulate the 

 milk. This is one reason why Cheddar cheese cannot 

 be made from sour milk. 



87. Acidity and expulsion of the whey. The con- 

 traction of the curd and expulsion of the whey are so 

 closely related that they may be treated under the 

 same heading. The more acid, the faster the whey 

 separates from the curd, other conditions being uniform. 

 The relation of acidity and firmness of the curd to temper- 

 ature of the curd is another important factor in the suc- 

 cessful manufacture of cheese. The higher the acidity, 

 the faster the temperature of the curd can be raised with- 



