REFRIGERATION OF FISH 

 Table 20 



581 



i Temperature correction 1° salometer for every 7' 2 ° F. added to reading for temperatures above 60° F., 

 subtracted below. There is also a salometer scale in use with 1° equal to M per cent salt 0= 1.0000 sp. gr. 

 100=1.19228 sp. gr., or 25 per cent salt. 



2 The freezing point of a brine is commonly understood to mean the temperature at which ice begins to 

 appear in it. In the solutions stronger than 22.42 per cent salt, salt, instead of ice, separates. 



To conform to Ottesen's principle it is necessary to keep the brine 

 in rapid motion. If agitation is not sufficient the mass of brine as a 

 whole may be at its " freezing point." while the brine film in immedi- 

 ate contact with the fish may be so warmed up as to be several degrees 

 above the " freezing point " and penetration may take place. For 

 the same reason the quantity of brine must be sufficiently large, in 

 proportion to the amount of fish present, so that the reserve ice is 

 sufficient to take care of initial freezing. (Each pound of mush ice 

 present will, in thawing, absorb 111 B. t. u. of heat from the fish.) 

 Precooling the fish before they are immersed in the brine is also 

 assumed to reduce the amount of penetrating salt. 



Amount of salt penetration.. — The amount of penetration of salt 

 into fish has been studied experimentally by various investigators, 

 Ehrenbaum and Plank froze large and small haddock in brine of 

 23.66 per cent salt, which dropped from 3.6 to 5.1° F. below zero 

 during the freezing. Under these conditions crystals of salt were 

 separating from the brine. Salt was determined in the surface 

 tissues to a depth of 5 millimeters (i/ 5 inch) before and after freezing. 

 The results are shown in Table 21. 



