98 PRELIMINARY COLD STORAGE STUDIES. 



and enzymes, and with such universal factors as air and light to be 

 considered, it is not to be wondered at that the whole question of 

 fat decomposition in nature is still greatly in need of elucidation. The 

 literature on the subject, as indicated in the foregoing discussion, is 

 chiefly concerned with plant oils and butter fat and with fats freed 

 from the tissues normally occurring with them. Almost invariably, 

 also, the studies made have been conducted at body or at room 

 temperature. The discussion of the changes in the fat of cold- 

 stored chickens as indicated by the variation between their values 

 and those of the fresh birds, which values are given in another 

 section of this report, becomes therefore a difficult task. Light, 

 as a cause of decomposition, need scarcely be considered; air, at 

 least for the superficial fats, is probably a factor and would tend to 

 increase the acidity. So great are the differences between the cold- 

 stored and fresh chickens when the acid value, saponification number, 

 and ester number are considered that probably not only air but en- 

 zymes as well, and perhaps bacteria too, have all played a part in the 

 alteration. The lowering of the iodin number rather argues for a 

 certain amount of bacterial action, as does also the decrease of the 

 saponification number, since the available contributions on the subject 

 agree in assigning such results to bacteria. The change in the Hehner 

 number due to bacterial action is not discussed to any extent in the 

 literature. Laxa, a in his study of butter, makes two determinations, 

 one for Oidium lactis and the other for B. Jluorescens liquefadens, 

 finding an increase in both cases. The Hehner number for fresh chick- 

 en fat is lower than is usually found for animal fats, and after cold 

 storage a further decrease is observed. It is difficult to explain the 

 cause of a rise in the Hehner number as a result of fungoid action, 

 since that is essentially katabolic, and not at all of the character to 

 produce acids of a higher type than those normally present, whereas 

 the decomposition of insoluble acids with the production of soluble 

 forms is perfectly logical and quite in line with the observations of 

 Rahn and Krueger. 



SUMMARY OF RESULTS. 



(1) Macroscopic observations of fresh and cold-stored chickens 

 show that certain plainly visible differences exist between the two 

 classes, which differences are progressive, depending on the length of 

 the storage period. 



(2) Chemical analyses of fresh and cold-stored chickens, wherein 

 were determined the total nitrogen for both dark and light meat and 

 its distribution between the classes of compounds commonly accepted 

 as the result of protein hydrolysis, the various values from which a 

 knowledge of the composition of fat may be obtained and such 



Loc. cit. 



