Page:Principles preservation fish by salt.djvu/17

Rh 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 permitted to be diluted if salt is present in crystalline condition.

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:

Since all the nitrogen in the brine was calculated as protein, these figures are undoubtedly too high; but the bulk of the nitrogen 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 and express the results in customary units, the figures show the equivalent amount of food-fish flash dissolved in brine to be 15.6, 39.2, and 18.4 ounces, respectively, or from 1 to 2½ 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 membranes. 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 fish 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?