582 L\ B. BUREAU OF FISHERIES 



Table 21. — Penetration of salt in haddock frozen in brine 



Salt in 5 millimeters 

 of surface 



Before 

 freezing 



After 

 freezing 



Large haddock. 

 Small haddock. 



Per cent 



0.11 



.17 



Per cent 

 1.57 

 2.05 



A similar trial was then made on fish in brine of 15 per cent salt at 

 11.1° F. above zero. Under these conditions crystals of water ice 

 were separating from the brine. Salt was determined in the outer 

 portion of the haddock before freezing, and one was wiped dry and 

 immersed in the brine while the other Avas immersed wet. The results 

 of this experiment are given in Table 22. 



Table 22 



Almy and Field 46 investigated the penetration of salt in brine 

 freezing of several common American fishes. Their conclusions, sup- 

 ported by several tables of analytical data, follow : 



Weakfish, flounders, herring, and whiting were frozen in chilled brine under 

 different conditions to determine the various factors which inflaence the pene- 

 tration of salt into the outer tissues of the fish. To assist in the determina- 

 tion of the degree of salt penetration, the skin and two successive layers of 

 muscular tissue just beneath the skin were analyzed for their content of pene- 

 trated salt. The muscular layers examined were usually one-eighth of an 

 inch in depth, a few being three thirty-seconds of an inch thick. It was found 

 that : 



1. Salt penetrated perceptibly into the skin and superficial muscular tissues 

 of all the fish under all conditions, the amount not being sufficient, however, to- 

 affect the taste of the cooked product. 



2. During the process of freezing the above species of fish under various 

 conditions the outer muscular layer one-eighth inch in depth absorbed from 

 0.32 to 6.22 per cent of salt on the dry basis, the average being 2.88 per cent. 



3. In a few instances the amount of salt absorbed by fish frozen in brine at 

 its freezing point was slightly less than that which occurred when the brine 

 temperature was several degrees above this point. In the majority of cases,. 

 however, no such temperature influence could be observed. 



4. When fish were frozen in brines of different concentrations but at the- 

 same temperature, no consistent differences in Ihe amount of salt absorbed by 

 The fish could be noted. 



5. Fish which had been precooled to near 32° F. before immersion in the 

 brine did not take up as much salt as those which were at atmospheric tem- 

 perature at this time, the absorption in the former case being 35 to 65 per cent 

 of that in the latter. 



46 L. H. Almy and E. Field, " The preservation of fish frozen in chilled brine. I. The- 

 penetration of salt." Journal of Industrial and Engineering Chemistry, vol. 13, pp. 

 927-928. Easton, 1921. 



