CHANGES IF FRESH BEEF DURING COLD STORAGE. 97 
on account of the deficiency of our knowledge regarding the nutri- 
tive values of the various cleavage products, it is by no means impos- 
sible that the nutritive value of beef may be decreased by unduly 
Jong periods of storage. 
FACTORS AFFECTING THE TIME THAT FRESH BEEF CAN BE 
STORED AT TEMPERATURES ABOVE FREEZING. 
One of the objects in conducting the series of experiments reported 
in this paper was to determine the length of time that fresh beef 
could be held in cold storage at temperatures above freezing and re- 
main in wholesome condition. The results of these experiments and 
of observations upon the commercial handling of fresh beef in cold 
storage have shown that the possible length of the storage period is 
affected by a number of factors. On account of the importance that 
has been attached to the time element in the cold storage of fresh 
beef, and in the storage of other fresh meats as well, it has seemed 
desirable to present a brief discussion of this phase of the subject. 
The principal factors which affect the length of time that fresh 
beef can be held in cold storage at temperatures above freezing are 
as follows: (1) The character of the beef; (2) the temperature of 
storage; (3) the humidity of the cold-storage room. 
Character of beef. — The condition of beef, as regards its degree of 
fatness or finish, is an important factor in determining the length of 
time that the beef will keep in cold storage. Thin, soft carcasses of 
old cows or grass-fed cattle are apt to undergo comparatively rapid 
deterioration in cold storage. The large exposed surface of muscular 
tissue and the soft character of the meat offer favorable conditions 
for the development of molds and bacteria. It is generally recog- 
nized by packing-house men that beef of this character must be 
handled with dispatch. On the other hand, highly finished carcasses 
from prime, grain- fed cattle will keep in cold storage for a much 
longer time. The flesh of such carcasses, which is firm in character, 
is usually covered in large part with a surface deposit of fatty tissue, 
which becomes firm on cooling and through loss of moisture, and thus 
aids in protecting the muscular tissue against bacterial invasion. 
Temperature of storage. — In commercial practice chilled beef is 
ordinarily held in cold storage at a temperature between 34° and 
36° F., although occasionally temperatures as low as 30° F. or as 
high as 40° F. may be employed. A temperature of 40° F. is regarded 
as about the upper limit of safety in the handling of fresh beef in 
cold storage, while it will freeze at a temperature slightly under 
31° F. Other conditions being the same it is clearly apparent that 
chilled beef will keep longest at 31° F. 
Humidity of cold-storage rooms. — The importance of dry coolers 
for the proper handling of chilled beef is generally recognized. As 
a rule, however, no special means are used to regulate the humidity 
of beef or other fresh-meat coolers, the desired condition usually be- 
ing obtained by the proper construction and management of the 
coolers. Various factors may affect the humidity of coolers, but they 
will not be discussed. 
There seems to be practically no information available regarding 
the humidity of packing-house coolers in this country. In order to 
secure accurate information on this subject, humidity readings were 
56861°— Bull. 433—17 7 
