COMMERCIAL FREEZING AND STORING OF FISH. 5 



For glazing, the frozen fish are taken to the glazing room, which 

 is held at a temperature of 20° to 25° F., or just cold enough to 

 cause thin layers of cold water to freeze rapidly. The glazers 

 slide the frozen cakes of panned fish, or the separately frozen fish, 

 quickly through a trough of clean, clear water held just above the 

 freezing point. (PI. IV, fig. 1.) This water covers the product 

 with a thin film which in the cold air freezes instantly into a crystal- 

 clear glaze of ice like a transparent varnish. Unless the water is 

 changed frequently, however, it is apt to collect oils or other material 

 from the fish which will prevent the glaze from forming evenly on 

 all parts of the fish or give the ice coating a cloudy appearance. 



Fish are passed through the water from three to five times until the 

 several coats of glaze form a sufficiently heavy and permanent ice 

 envelope covering the entire surface. Even before glazing the blocks 

 of frozen fish in the pans have become solid cakes, the fish being 

 held together by the freezing of the thin layer of water between them, 

 and the glazing still further cements them to each other. Glazing 

 of fish adds about 5 per cent to their weight, although this varies 

 with the size of the fish and the number of glazings. To expedite 

 the glazing of separately frozen fish, operators on the Pacific coast 

 place the fish on small platforms, which are lowered by a winch into 

 a tank of water and raised again. This process is repeated until 

 the glaze which hermetically seals the fish and prevents deterioration 

 is of the proper thickness. 



COLD STORAGE OF FISH. 



The glazed fish are taken immediately to the cold-storage rooms 

 to be kept until sent to market. (PI. IV, fig. 2.) These are rooms 

 with coils of ammonia or brine pipes attached to walls and ceilings, 

 but not arranged in the form of shelves, as in the freezing rooms. 



The subject of the proper temperature for the long storage of 

 frozen fish has been much discussed. Investigation seems to prove 

 that ordinarily the most economical and safest temperature for hold- 

 ing fish is at any point from zero to 10° F., with as little variation 

 in temperature as possible. Some plants, especially small establish- 

 ments in isolated localities, try to keep their frozen fish at from —5° 

 to +5° F., because fish held at these temperatures would not spoil 

 quickly should an accident to the refrigerating machinery interrupt 

 artificial refrigeration for a day or two. 



In determining the temperature of the storage room, operators are 

 cautioned not to be guided by floor temperatures alone, but to place 

 thermometers so that readings can be taken at the top of the room, 

 to which the warmer air naturally rises, affecting the uppermost 

 fish. It is suggested that if the owner can not provide two or more 

 thermometers he hang a thermometer from a pulley on the ceiling 

 32658°— 18— Bull. 635 2 



