CHAITGES IN FRESH BEEF DURING COLD STORAGE. 95 



explained by the comparatively large increases in the amount- of free 

 fatty acids present in those samples. 



Free fatty acids. — There was a marked and continuous increase in 

 the free fatty acid content of the external and kidney fats during 

 the course of the storage experiments and a eorresponding deteriora- 

 tion in the quality of those fats. The average actual increase in the 

 acidity of the two fats ranged from 0.46 per cent in the case of the 

 beef stored 14 days to 9.76 per cent in the case of that stored 177 days. 

 The changes in the acidity of the intermuscular fat were compara- 

 tively small, varying from an increase of 0.17 per cent in the case of 

 the beef stored for 14 days to an increase of 1.42 per cent in the 

 case of that stored for 74 days. The reason for the slight increase in 

 the acidity of the intermuscular fat as compared with the large 

 increases in the acidity of the kidney and external fats is clearly ap- 

 parent. The intermuscular fat was protected from bacteriological 

 invasion by its covering of muscular and external fatty tissues, while 

 the kidney and external fats were exposed to the invasion of molds 

 and bacteria. The changes that took place in the intermuscular fat 

 were due, in very large part at least, to the action of the enzym 

 lipase, while the changes that took place in the kidney and external 

 fats were due principally to bacterial action. 



EFFECTS OF COLD STORAGE UPON THE NUTRITIVE VALUE OF 



THE BEEF. 



Several factors must be taken into consideration in order properly 

 to interpret the results of these experiments in terms of their effect 

 upon the nutritive value of the meat. The more important factors 

 are as follows: (1) Changes in the moisture content of the meat; 

 (2) changes in the proportions of nonedible and edible meat in the 

 quarters of beef; (3) changes in the composition of the meat. 



The analytical data obtained in these experiments show that, with 

 the exception of the quarter of beef that had been stored for 14 days, 

 each of the quarters lost moisture during storage, and that in general 

 the decrease in the moisture content of the meat was greater the 

 longer the storage period. This loss of moisture is in effect a process 

 of concentration, causing an actual increase in the amount of food 

 constituents present in a given weight of stored meat, as compared 

 with that present in a like weight of fresh meat. Thus, by referring 

 to Tables 19, 26, 33, 40, 47, and 54 it may be noted that the average 

 percentages of total nitrogen, fat, and ash increased during the 

 storage period of each experiment, and that in general the increase 

 was greater the longer the period of storage. These data show the 

 composition of the lean moat and are a fair indication of the extent 

 to which the nutritive value per given weight of meat was increased 

 through loss of moisture. 



The increase in nutritive value, however, is only apparent, not 

 real ; for while the loss of moisture effects an increase in the nutritive 

 value of the meat per unit weight, it also diminishes the weight of 

 the carcass; so that at best the carcass contains no more nutritive 

 material after storage than before. Indeed, the available food ma- 

 t^'rial in the carcass (ends to become h-ss; for, in conscrjiionce of the 

 drying out and rh^tcrioration in quality of the ex|)os('(] muscular and 

 fatty tissues, there is greater wastage in the preparation of the retail 



