578 "L T - S. BUBEAU OF FISHEEIES 



partments and several compartments for fish, wherein the brine is 

 pumped through flexible nose. 



A small plant, built after the Dahl design, for freezing with ice 

 and salt brine, was built in Fernandina, Fla., for freezing shrimp. 

 The ice and salt were put in chambers, and the brine formed was 

 circulated by a centrifugal pump through the freezing chamber. 

 Shrimp were dumped directly into the brine. They froze in a few 

 minutes. They were left in it about three minutes, taken out, drained 

 a few minutes on the floor, boxed, and stored at about 0° F. At first 

 these shrimp appeared to be of excellent quality, but after a few 

 months' storage they developed a bad appearance. The delicate pink 

 changed to a less pleasing orange color, blackish in places, and the 

 meat darkened. On microscopic examination the otherwise beautiful 

 tentacled pigment cells were found to have disintegrated. Direct 

 freezing in brine appears to be unsuited to shrimp. This criticism is, 

 of course, no more applicable to DahFs method of freezing than to 

 others wherein brine comes into direct contact with the shrimp. 



OTTESEX's METHOD 



A. J. A. Ottesen, 44 of Thisted. Denmark, patented in several coun- 

 tries a principle that has to do with the relation of the temperature 

 and concentration of brine to the penetration of salt into the fish. As 

 the question of salt penetration is an important one for all methods of 

 freezing where the fish come into direct contact with brine, space 

 will be taken here to discuss this subject at some length. 



PENETRATION OF SALT INTO FISH IN BRINE FREEZING 



It is a well-known fact, of course, that fish or other flesh substances 

 when treated with salt absorb some of the salt that diffuses through- 

 out the tissues. Likewise, some of the water in the tissues passes out 

 and dissolves the salt, to form brine. When strong brine is used 

 instead of dry salt, the same exchange occurs in a somewhat 

 diminished amount — salt penetrates the fish and water comes out and 

 dilutes the brine. This exchange of water and dissolved substance 

 is called osmosis. Osmosis always occurs whenever a permeable mem- 

 brane (in this case the cell membranes) separates a strong solution 

 of a crystallizable substance from water or a weaker solution (in this 

 case the fish juice). Osmotic pressure (the tendency to osmose) 

 diminishes with diminishing temperature. 



Salt penetration is a much slower process than the freezing of 

 fish in brine. A fish that under the most favorable conditions would 

 salt through in 24 hours will freeze in brine in one-half an hour. 

 Nevertheless, even a small amount of penetration is objectionable. 

 It interferes with glazing; for just as salt dissolved in water lowers 

 its freezing point just so does it lower the freezing point of the sur- 

 face tissues of the fish and prevents a glaze from sticking. Also, 

 if salt is present in any considerable proportion the flavor will be 



**U. S. Patent 1129716. Feb. 23. 1915: British Patent 24244, Sept. 4, 1913: French 

 Fatent 449815. Jan. 4. 1913. Patents were also issued to him in most of the other 

 important fishing countries of the world. 



