REFRIGERATION OF FISH 585 



similar to our ordinary ice-pulling crane. There is a preliminary 

 dipping or washing tank with running water. The brine tank is 

 divided into eight compartments, each with its individual circulating 

 pump. The baskets containing the washed fish are lowered into their 

 respective compartments and the covers are put on. Operations are 

 so timed that when the last basket is put in the first is ready to come 

 out. The baskets are then successively dipped in,to the eighth, or 

 fresh-water, tank, after which dipping they go to the glazing and 

 packing room, which is held at 14° above zero, F. The packed fish 

 are conveyed by elevators to upper floors. 



Schlienz does not describe any means for maintaining constant 

 composition or temperature of the brine. 



Another room in the plant is provided with woodworking ma- 

 chinery for removing skins, fins, and entrails from the frozen fish, 

 which* are dressed for the preparation of fillets and steaks. The 

 fillets are made either as entire fillets or cut into portions of from 

 4 to 8 ounces. 



Schlienz says that it is necessary to reglaze the fish every 4 to 6 

 weeks, and that if this is done they can be kept without damage for 

 9 months. He finds difficulties, however, with fat fish like halibut, 

 turbot, mackerel, and herring, in which the fat becomes rancid on 

 storage. This is an understandable difficulty, since the temperature 

 of 14° maintained in the storage rooms is well known in this country 

 to be too high for that purpose. 



The present writer has had opportunity to examine cod fillets of 

 the small size prepared by this process, as shipped. They are in a 

 wooden box of 25 pounds net weight, wrapped in 30 packages. The 

 wrapper is paper, not parchmentized, not waxed, not printed, and 

 held with a rubber band. Each package contains one or two pieces 

 of a size, shape, and thickness that depends on the part of the fish 

 from which it comes. 



The pieces themselves are skinless and are made by clean cuts of the 

 fish in the frozen condition, the cut surfaces being flat or squarish, and 

 not at all ragged. There is a groove where the backbone was, sug- 

 gesting that the bone has been removed with a half-round chisel, such 

 as is used in wood turning. In cross-section the internal structure 

 is free from crystals and is in excellent condition. There is some 

 development of yellow color outside, a condition that always develops 

 in frozen cod and haddock fillets unless preventive measures are 

 taken. On being defrosted the fillets are markedly juicy, indicating 

 a change in the hydration of the protein. The elastic, gelatinous 

 consistency of fresh cod muscle has disappeared. When cooked the 

 flesh is somewhat dry and rather coarser than that of fresh cod be- 

 cause of the change just mentioned. The flavor is good and no 

 saltiness is observed. 



Ottesen also patented 52 a brine with an organic substance (gly- 

 cerin) added in order further to reduce its freezing point. 



Glycerin and water mixtures of low freezing point are well known 

 for use; for example, for automobile radiators. When glycerin is 

 added to a salt brine the freezing point of the mixture is lower 

 than would be that of the glycerin or salt alone with the water. The 



62 U. S. Patent 1532931, Apr. 7, 1925. 



