PRESERVATION OF FISH BY SALT. 11 



at a higher temperature. The superiority of dry salt over brine 

 resides in the fact that the brine in contact with the fish is not per- 

 mitted to be diluted if salt is present in crystalline condition. 



LOSS BY FISH OF NUTRIENTS IN BRINE. 



The liquid that comes from fish during the salting process is not 

 pure water, as every fisherman knows, but contains a quantity of 

 material derived from the fish. Most of the nitrogenous matter 

 found in brine represents just so much good food gone to waste and 

 just so many pounds of fish that might have fetched a good price 

 gone overboard. The quantity of protein that escapes into the brine 

 is highly variable, for reasons that will appear later. That some 

 idea may be had of the magnitude of the loss of fish substance in 

 brine the following figures are given. These figures were obtained 

 in the course of investigation on the recovery of valuable materials 

 from old brine: 



Ix)ss BY Fish of Nutrient Materials in Brine. 



Brine. 



Grams 



dry 

 protein 

 per liter 

 of brine. 



Avoirdu- 

 pois 

 ounces 



per 

 gallon. 



Rockfish brine from Alaska 



Herring brine from Gloucester . 

 Cod brine from Gloucester 



29.30 

 34.80 

 73.30 



3.9 



9.8 

 4.6 



Since all the nitrogen in the brine was calculated as protein, these 

 figures are undoubtedly too high ; but the bulk of the nitrogen is cer- 

 tainly of protein origin, so the figures may be taken, to illustrate the 

 point made. If we assume fresh fish to be 75 per cent water and 25 

 per cent dry protein and express the results in customary units, the 

 figures show the equivalent amount of food-fish flesh dissolved in 

 brine to be 15.6, 39.2, and 18.4 ounces, respectively, or from 1 to 2^ 

 pounds to the gallon of brine. Bitting ^ calculated the losses in the 

 curing of codfish as follows : Loss of weight in dressing, 40 per cent ; 

 loss in salting, 40 per cent of what remained after dressing; drying 

 on flakes, 9 per cent of the salted fish. The 40 per cent of the dressed 

 fish contains besides water much protein or valuable nitrogenous food. 

 It would certainly seem to be worth our while to examine into the 

 causes of this loss and to prevent or salvage it if possible. 



How does this protein get out of the fish? It was said above that 

 protein is a colloid and that colloids do not diffuse through mem- 

 branes. A small amount must come from the blood and from the cut 

 surface on the fish, but most of it will probably be found to come from 

 the interior cells by a process not yet investigated. We do know 

 something directly about autolysis, however, the great enemy of the 

 fisli dealer, which liquefies the contents of fish flesh, and we have 

 every reason to believe that if autolysis were stopped the losses of 

 protein into brine would be reduced to a minimum. What is autolysis 

 and how does it do its damage ? 



s Bitting, A. W. : Preparation of Cod and Othex Salt Fish for Market, IT. S. Depart- 

 ment of Agriculture, Bureau of Chemistry, Bulletin No. 133, 63 p. Washington, 1911. 



