REFRIGERATION OF FISH 595 



13. Avoidance of exposure of working parts to the brine is a 

 matter of machine design and composition of brine to minimize for- 

 mation, of rust in the pipes, the same material, not galvanized, being 

 used throughout. 



14. By conveying the fish mechanically through the successive 

 sprays of water, brine, and water, all necessary operations of wash- 

 ing, freezing, and glazing are done automatically, the only labor re- 

 quired being to put the fish in at one end of the apparatus and to 

 remove them from the other. 



The apparatus 64 takes the form of an insulated tunnel, say, 40 feet 

 long by 4 feet wide, the dimensions being determined by the desired 

 capacity. A mechanical conveyer operates in the top of the tun- 

 nel to convey horizontal bars through. On these bars the fish are 

 suspended by head or tail. They hang thus and are frozen 

 straight. The conveyer is adjustable for speed, so that large fish 

 may be made to travel more slowly than small ones. 



At the entrance end of the tunnel are provided sprays that give 

 a violent shower of fresh water, washing the fish in clean running 

 water. The fish then travel through a shower of brine at 5° or 6° 

 below zero for, say, 32 feet, at a speed so adjusted as to freeze 

 them by the time they reach the other end. When they emerge from 

 the brine spray they pass under two fresh-water sprays. The first 

 washes off the brine and, after draining a moment, the second applies 

 the glaze. The fish then emerge washed, frozen, and glazed, and are 

 ready to be packed. 



The brine is pumped by a centrifugal pump and is cooled prefer- 

 ably outside the tunnel by a thermostatically regulated cooler, though 

 it may be cooled in the tunnel, as shown in Figure 34. The time of 

 travel of fish through the complete process varies from 15 minutes 

 for smoked fillets of haddock to 3 hours for large salmon and halibut. 

 Small fish, fillets, shrimp, oysters, and squid may be frozen by put- 

 ting them in a can or other container and treating the containers 

 like fish. Thus the flexibility of the apparatus is great. 



A plant of this design and with a capacity of 15 tons of fish in 

 24 hours was constructed and operated in the Fishery Products 

 Laboratory of the Bureau of Fisheries in Washington, D. C. It 

 operated entirely satisfactorily under the experimental conditions. 



FOAM IN BRINE 



There is a tendency for foam to form in any brine freezer. The 

 violent spraying of brine in this machine causes considerable for- 

 mation of foam, a phenomenon that has required some study. The 

 slime and blood on the fish, and other substances from the fish, if not 

 washed off, are contributory causes. It was found also that the 

 cruder grades of sea salt that we used in brine freezers contain a con- 

 siderable quantity of an oily substance like petroleum. If the foam 

 is collected, drained, and dried, a dark, sticky mass remains, partly 

 soluble in ether and smelling like petroleum. It may be derived 

 from decaying animals in the sea or may possibly be derived from 

 ships. 



M H. F. Taylor, U. S. Patent 1468050, Sept. 18, 1923; Canadian Patent 236588, Dec. 

 25, 1923. 



22279—27 7 



