604 U. S. BUEEAU OF FISHERIES 



slight pressure on the contained fish. For halibut a two-edged con- 

 tainer is used. These sheathlike containers are mounted in batteries 

 and otherwise handled in the same way as the cans for cake-frozen 

 fish. 



Fish frozen by this method (for which Peterson has coined the 

 word, "keenkooling") are trim, straight, and, of course, take an 

 excellent glaze. The bellies of dressed fish are closed. Here, again, 

 the principal difficulty would be to have a sufficient variety of sizes 

 and shapes to accommodate the general run of fish received at a fish 

 freezer. There could scarcely be objection to the internal quality 

 of fish so frozen unless on the academic ground suggested by Plank 

 (p. 598) of freezing at excessively low temperatures. An excessively 

 low temperature, of course, is not essential to Peterson's method of 

 freezing, because any temperature may be chosen. The only reason 

 for the low temperatures actually used is to secure the benefit of the 



Fig. 39. — Petersen's method for freezing fish singly. Lake trout frozen in a thin 

 metal sheath. Courtesy, Bay City Freezer 



most rapid freezing possible. In this connection it may be noted 

 that Peterson secures the necessary rapid freezing, not by particularly 

 good contact with the refrigerant brine, but by a low temperature. 

 It appears, in the absence of actual figures for comparison, that 

 this method freezes at about the same rate in brine at 20° below 

 zero as direct brine freezing does at 5° below zero. Refrigeration, 

 as pointed out above, generally costs more per ton the lower the 

 temperature. 



Direct brine freezing seems to give the best possible contact but 

 introduces difficulties of brine penetration, while indirect brine 

 freezing avoids penetration but requires lower brine temperature to 

 secure the necessary speed. The advantages or disadvantages are 

 thus not all on one side. 



kolbe's method 74 



R. E. Kolbe. of Erie, Pa., has made an adaptation of the ordinary 

 freezer pan to immersion in brine freezing without contact of brine 



74 " Brine freezing of fish," by Robert E. Kolbe. Ice and Refrigeration, vol. 70, pp. 

 205-206. Chicago, 1926. 



