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- 

 stan<:e appears to occur only rarely, except in the case 

 of cheese ripened near freezing point. 



(c) Proteoses or caseoses (albumoses), whi^h 

 are proteins or p'rotein 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 



