198 THE BOOK OF CHEESE 



break it up. After cutting, a thin film forms on each 

 piece of curd. This film holds the curd particles, especially 

 the fat. Breaking the films on the cubes causes loss of 

 fat. If lumps form at the early stage, by matting of the 

 curd particles, violent stirring is required to separate 

 them. When such lumps are broken up, new cleavage 

 lines are formed with loss of fat, because the original 

 films surrounding the soft curd fuse so firmly that the 

 curd cubes do not separate but actually break. New 

 surfaces are thus formed with consequent fat loss. Rapid 

 shrinkage with expulsion of whey takes place during the 

 first few minutes of gentle agitation. Before any heat is 

 applied to the vat, sufficient whey should have separated 

 or formed to float each piece of curd separately. This 

 will require ten to fifteen minutes from the time of cutting. 

 Thus far the first of three distinct factors which expel 

 the moisture from the curd has been considered : (1) the 

 action of the rennet; (2) the development of the lactic 

 acid; and (3) the application of heat. These forces 

 must have time to act naturally. If heat is applied too 

 soon after the curd is cut or if the temperature is raised 

 too rapidly, it causes a thick film to form on the pieces 

 of curd which interferes with the escape of the whey. 

 The outside of the curd becomes firm but the inside re- 

 mains very soft. A curd which is cooked on the outside 

 only feels firm when stirred by hand in the whey, but 

 when a handful is squeezed the soft centers are noticed. 

 To firm such curd masses requires violent stirring, which 

 will break the thick tough film. This allows the mois- 

 ture to escape and also increases the fat loss. The 

 rapidity of heating should depend on the condition of 

 the curd and the amount of acid developed. The heat 

 should keep pace with these. When ready to raise the 



