sept, n, 1916 Progressive Oxidation of Cold-Storage Butter 



945 



Table XVI. — Chemical constants of the fat of unwashed butter, with high content of non- 

 fatty ingredients , stored at 0° F. 



[Protein 0.90 per cent. Total XX6.38] 



The same comments are here to be made as in the case of the previous 

 sample of nearly pure butter fat. No noteworthy chemical change had 

 occurred in this sample of butter fat after having been kept in storage at 

 a temperature of o° F. for a period of six months. With respect to the 

 fat taken from the sample of butter so prepared as to contain the greatest 

 number of constituents in addition to the fat, the same observations are 

 here to be made as in the previous cases of two different lots of butter 

 containing smaller numbers of nonfatty constituents. The chemical 

 constants here show little or no variation from those obtained with the 

 nearly pure butter fat, and there is apparently no chemical change in the 

 fat of butter prepared with a still greater number of substances in addi- 

 tion to the fat, owing either to the presence of these substances or to the 

 presence of the confined air. An analysis of this confined air, however, 

 gives some very striking data (Table XVII) when compared with those 

 obtained in the foregoing samples. 



Table XVII. — Analysis of air in unwashed butter, with high content of nonfatty 

 ingredients, stored at 0° F. 



[Calculated to o° C. and 760 mm. Protein 0.90 per cent. Total XX6.38] 



Total gas. 



Months 

 2 



3 



4 



5 



15 



C.c. 

 29. 26 

 28. 23 

 29- 15 



38.19 



33-28 



Total carbon dioxid. 



Per cent. 

 3 1 - 41 

 3I-67 

 27.89 

 26. 12 

 22. 26 



Total oxygen. 



C.c. 



02 



47 

 37 

 37 



Per cent. 



2-43 

 2. 20 

 1. 61 



•97 

 1. 11 



Calculated 

 oxygen. 1 



C.c. 



4. OI 

 3.86 

 4. 20 

 5-64 



5- *7 



1 After deducting the figure for carbon dioxid from the total quantity of gas extracted from the tube and 

 assuming that the residual gas is pure air — that is, approximately one-fifth oxygen. 



The maximum content of carbon dioxid (31.67 per cent) in this sample 

 of unwashed butter was noticed after a storage period of three months, 

 at about which time the characteristic "off flavor" became distinctly 

 noticeable. At the end of two months there was very little oxygen in 

 the sample; yet even this shows a perceptible decrease during the storage 

 interval. 



