Setting and Cutting 253 



temperature of the milk. So soon as the rennet is 

 added, the milk should be quickly and carefully 

 stirred, so that the rennet may be uniformly mingled 

 with every part of it. This stirring should continue 

 until the mixture of rennet and milk is complete, 

 but should stop before any appearance of coagula- 

 tion. The milk in the vat is then allowed to be- 

 come quiet, and remains undisturbed while the pro- 

 cess of coagulation is going on, the object being to 

 secure a uniformly solid clot or coagulum through 

 the mass. The action of the rennet is not instanta- 

 neous ; the first appearance of coagulation is noticed 

 by a slight thickening of the milk. This gradually 

 increases until the whole mass is solid, and if left 

 undisturbed the action of the rennet continues to 

 contract the coagulated casein and cause a partial 

 separation of the whey. As soon as the coagulation 

 is strong enough, so that the casein will maintain 

 its shape when broken, the contents of the vat are 

 ready for the next step in the process. 



Period II., cutting. The curd, as the coagulated 

 casein is called, is ready for cutting when under 

 strain it will break with a clean fracture. This is 

 conveniently tested by gently inserting the finger in 

 the curd in an oblique position and slightly raising 

 it, when if the curd breaks clean across the finger 

 it is sufficiently firm for cutting. Cutting is per- 

 formed in order to facilitate the further contraction 

 of the casein and the expulsion of the whey. For- 

 merly the solid mass of curd was broken up into 

 small pieces by any sort of an instrument that 



