262 Report of the Chemical Department of the 



(5) Salt. — Cheese containing more salt forms water-soluble 

 nitrogen compounds more slowly than cheese containing less salt. 

 This appears to be due, in part, to the direct action of salt in re- 

 tarding the activity of one or more of the ripening agents and, in 

 part, to the tendency of the salt to reduce the moisture content of 

 the cheese. 



(6) Rennet. — The use of increased amounts of rennet-extract 

 in cheese-making, other conditions being uniform, results in pro- 

 ducing increased quantities of water-soluble nitrogen compounds 

 in a given period of time, especially such compounds as paranu- 

 clein, caseoses and peptones. 



(7) Acid appears to be essential to- the formation of water- 

 soluble nitrogen compounds in normal cheese-ripening, but the 

 exact influence of varying quantities of acid upon the chemical 

 changes of the ripening process has not yet been fully studied. 



transient and cumulative products in cheese-ripening. 



In studying the influence of various conditions upon the chemi- 

 cal changes of the nitrogen compounds in the normal cheese- 

 ripening process, we have noticed that the compounds grouped 

 under the names, paracasein, caseoses and peptones, usually vary 

 within comparatively narrow limits and do not appear to accumu- 

 late in the cheese in constantly increasing quantities. These com- 

 pounds do not appear to show much definite regularity in the 

 amounts formed under different conditions. On the other hand, 

 amido compounds and ammonia accumulate in increasing 

 amounts from the early age of the cheese during the whole pro- 

 cess of normal ripening. The difference in the apparent behavior 

 of these different classes of nitrogen compounds is most readily 

 explained by regarding the compounds first formed in cheese- 

 ripening as intermediate transient products. Thus we find para- 

 nuclein, caseoses and peptones present in the earliest stage of 

 cheese-ripening, and they show a tendency to increase somewhat 

 for a period of time and then decrease. Just what the chemical 

 relation of these compounds is to paracasein or to paracasein mon- 

 olactate, we are unable to say. It is probable that the molecule 

 of the proteid compound first splits into paranuclein and caseoses 

 or some closely related compounds and from one or both these 



