756 MARINE PRODUCTS OF COMMERCE 



cidity of the fat. Both of these problems are highly important in cases where it 

 is necessary to hold frozen fish in cold storage over a period of months. The 

 length of time fish are held and the temperature of storage are the most impor- 

 tant factors in determining the quality of the stored product. 



The importance of the proper type of wrapping materials has been pointed out 

 many times. These can cause serious losses in storage, in both the quality of the 

 product and a direct loss of weight to the producer. This applies to all frozen 

 packaged products. If 1 ton of product is placed in a cold storage warehouse and 

 loses even as little as 1 per cent of its weight in the form of moisture, 20 pounds 

 is lost. 



The quality of various types of wrapping materials has been investigated for 

 many years. Some of these materials are highly eflficient for regular-shaped pack- 

 ages. Most packages of fish cannot be completely filled because of the irregular 

 shape of the fish put into them. In these packages there are spaces filled with air, 

 and even though the WTapper is successful in excluding outside air, there is a 

 sufiicient amount entrapped to do considerable damage. A packing material is 

 needed which is flexible enough to fit the contour of the irregularly shaped fillets 

 of fish and leave no air space. It should not become brittle when cold and should 

 not deteriorate when placed in cold storage over a period of many months, 

 A wrapping material which is completely satisfactory would do much to eliminate 

 losses caused by freezer burn and oxidation in frozen fish. 



One highly efiicient wrapping material has been developed from synthetic 

 material, known as the "Cryovac" bag when formed. This bag can be drawn over 

 a package of fish and shrunk by dipping in hot water until it fits skintight. Freez- 

 ing does not afi^ect the flexibility of the material. However, large fish, such as salmon 

 and halibut, are diflBcult to handle since the fins often puncture the material 

 and render it worthless for preventing evaporation. 



Many species of large fish, such as halibut, salmon, and swordfish, are frozen 

 and stored whole. To protect these species during long storage periods, it is neces- 

 sary to replace the glaze at intervals. These intervals vary in length, depending 

 upon the temperature of the storage room and the humidity maintained. If some 

 type of covering material could be produced which would fit the fish like its own 

 skin and yet be impervious to the transfer of moisture vapor and oxygen of the 

 air, it would eliminate the necessity of reglazing, and thereby save the warehouse 

 operator hundreds of dollars. It would also result in a higher quality stored fish 

 since it would eliminate freezer bum and oxidation to a large extent. 



Shellfish Freezing Problems 



Problems of the storage of shellfish are of considerable importance to the indus- 

 try. Many shellfish do not store well when frozen. Clams are seldom frozen for 

 long storage as they become rubbery. Shrimp and crabs become tough and lose 

 much of their flavor when stored frozen for too long a period of time. Oysters 

 often turn black and become strong upon long periods of storage. These prob- 

 lems should be thoroughly investigated. 



A problem of major importance to the frozen-fish industry and to all frozen- 

 package food industries is that of the education of the retail dealer in the proper 

 ways of handling these products. Much has been accomplished along this line, 

 but there are still many hundreds of retail merchants who display their frozen 



