330 SCIENCE AND PRACTICE OF CHEESE-MAKING 



changes in cheese proteins during ripening, owing 

 largely (i) to a lack of detailed knowledge of the 

 compounds formed and (2) to need of more perfect 

 methods for estimating the amounts of these com- 

 pounds, many of which are formed only in very small 

 quantities. 



Beginning with the milk-casein in the cheese-vat 

 at the time the rennet is added, we have, from that 

 time on, a succession of changes in the curd and 

 cheese, resulting sooner or later in the formation of 

 a series of compounds, which, so far as our present 

 knowledge goes, appears in something like the fol- 

 lowing consecutive order: 



(1) Calcium paracasein (formed from the cal- 

 cium casein of milk by action of rennet). In- 

 soluble in water and in warm, 5 per -cent salt-brine. 



(2) Protein soluble in warm, 5 per cent salt-brine. 

 (Figs. 30 and 31, p. 148.) 



(3) Protein insoluble in salt-brine, water, etc. 



(4) Proteins soluble in water: 



(a) A protein which is precipitable by dilute 

 hydrochloric acid, called paranuclein. 



(b) A protein substance coagulated in neutral 

 solution at the boiling point of water. This sub- 

 stance appears to occur only rarely, except in the case 

 of cheese ripened near freezing point. 



(c) Proteases or cas eases (albumoses), which 

 are proteins or pfrotein derivatives soluble in water, 

 not coagulated by heat, and usually precipitated by 

 saturating their solutions with zinc sulphate or am- 

 monium sulphate. 



(d) Peptones, protein derivatives simpler than 

 the proteoses, soluble in water, not coagulated by 



