240 Report of the Chemical Department of the 



ripening start with and are dependent upon the presence of para- 

 casein monolactate or some similar compound. Hence, from a 

 -chemical point of view, cheese-ripening consists mainly of the 

 change of paracasein monolactate into other forms of nitrogen 

 compounds, chief among which in the order of their formation 

 are paranuclein, caseoses, peptones, amido compounds and 

 ammonia. These compounds, formed from paracasein mono- 

 lactate, are readily soluble in water, while paracasein monolactate 

 is not. Hence, in ripening cheese we have larger amounts of 

 substances that are soluble and smaller amounts of substances 

 that are insoluble than in green cheese. Ripening cheese is 

 believed, for this reason, to be more readily digestible than 

 green cheese. The amount of soluble nitrogen compounds is 

 used as a measure of the extent of cheese-ripening. 



This present investigation offers an opportunity of studying 

 the chemical results of cheese-ripening under dififerent conditions 

 of temperature and with a number of different types of cheddar 

 cheese under commercial conditions. 



(2) Moisture in cheese. — Before taking up a study of the nitro- 

 gen compounds of the cheeses under investigation, we will call 

 attention to the amount of moisture in the cheese. 



In the case of Lots I, H, HI and IV, in which the moisture 

 was determined when the cheese was placed in cold storage, we 

 found the moisture content varying from 34.20 to 35.44 per ct.; 

 this may be regarded as a comparatively small variation. In 

 Lots IV and V, the moisture must have been above 40 per ct, 

 at the time the cheese was placed in cold storage, because 10 

 weeks later, when we made the first analysis, the moisture was 

 about 39 per ct. The results of moisture determination show a 

 gradual decrease in moisture as the cheese becomes older, as 

 indicated by the following averages: 



Percentafje of moisture in cheese. 



When put in cold storage 36 50 per ct. Ai40°F. At ^0° F. At6o°F. 



After being in storage 10 wks 36.30 35-70 3565 



" " " 20 " 35.35 34.66 3426 



The decrease of moisture is greater with increase of tempera- 

 ture, a point which has been dwelt upon in connection with loss 

 of weight. 



