Taylor. — Preservation of Fish by Salt 135 



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

 these figures are undoubtedly too high, but the bulk of the nitro- 

 gen is certainly 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, 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^/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 re- 

 mained after dressing; drying on flakes, 9 per cent of the salted 

 fish. The 40 per cent of the dressed fish contains much pro- 

 tein 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 membranes. A small amount must come from the 

 blood, and from the cut surfaces on the fish, but most of it 

 will probably be found to come from the interior cells by a pro- 

 cess not yet investigated. We do know something directly 

 about autolysis, however, the great enemy of the fish dealer, 

 which liquifies 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 ? 



Protein, the colloid, cannot pass through an osmotic mem- 

 brane. But proteins can be decomposed into simpler substances 

 which readily dissolve and pass through. The agency which 

 breaks protein down into these simpler substances is called an 

 enzyme, and protein must always be so liquified or digested by 

 enzymes before it can be absorbed through membranes. Hence 

 the necessity of digestion in the stomach of animals prepara- 

 tory to absorption through the intestines. Now animals, includ- 



*Bitting, A. W. Preparation of Cod and Other Salt Fish for Market. U. S. Depart- 

 ment of Agriculture, Bureau of Chemistry, Bulletin No. 133, 63 pp., 191 1, Washington. 



