CHANGES IN FRESH BEEF DURING COLD STORAGE. 6 
down to about 32° F. before filling, though when filled with warm 
beef it may run up to 50° F. 
The main cooler is simply a second cooler into which the par- 
tially chilled beef from the fore cooler is run to be thoroughly 
chilled and held for shipment. In some of the large meat-packing 
establishments, which have several beef coolers, warm beef is run 
into one cooler on one day, into another cooler on the second day, 
and so on, the chilled beef being removed from the first cooler in 
time for its refilling with warm beef. This practice accomplishes 
the same result as the use of a fore cooler. 
SYSTEMS OF REFRIGERATION. 
In commercial meat-packing establishments in this country the 
ammonia-compression system of refrigeration is used almost entirely. 
There are, however, a number of methods by which the refrigeration 
is distributed for the purpose of chilling the coolers. The more 
important of these are: (1) Closed brine-coil system; (2) sheet-brine 
system; (3) brine-spray system. In each case the refrigerating agent 
is sodium chlorid or calcium chlorid brine that has been chilled by 
the direct expansion of liquid ammonia in closed coils. 
Closed-coil system. — Refrigerated brine is pumped through closed 
coils located in bunkers directly above the coolers. The bunkers are 
so constructed as to provide for gravity circulation of air, the cold 
air falling from one side of the bunker into the cooler below and 
the warm air from the cooler rising at the other side to be refrig- 
erated as it passes over the brine coils. This system also accom- 
plishes a partial drying of the air as it passes over the cold brine 
coils, which condense a part of the moisture and the dissolved im- 
purities that the air contains. The closed-coil system is the one most 
commonly used for the refrigeration of fresh-meat coolers. 
Sheet-brine system. — This system is similar in principle to the 
closed-coil system. Instead of passing through closed coils, how- 
ever, the refrigerated brine is allowed to trickle over a series of sus- 
pended muslin curtains located in a bunker room similar to that used 
in the closed -coil system. 
Brine-spray system. — In this system the refrigerated brine is 
sprayed from a series of pipes located in a bunker room similar to 
that which is used in the two other systems. One advantage of this 
system over the other just mentioned is that less head room is required 
in the bunker room. 
, When properly installed any one of these systems is considered 
to give satisfactory results. It is very important, however, that a 
system of refrigeration for fresh-meat coolers should provide for 
abundant refrigeration and for a thorough and fairly rapid circula- 
tion of air. - 
