84 U. S. BUREAU OF FISHERIES 



in the spring, and rental charges for holding the frozen fish in cold 

 storage over a longer period of months, as would be necessary, would 

 be increased. 



SMOKED MACKEREL AND STORAGE OF THIS PRODUCT 



At periods during the peak of the mackerel season, it often becomes 

 •difficult for the trade to dispose of this fish in the fresh condition. 

 This has lead to depressing prices with consequent lowering of the 

 income of mackerel fishermen. It has become increasingly evident 

 that some different method of preservation is needed for mackerel 

 which will present a new "appetite" appeal to consumers for this 

 fish. In view of this, a study was begun, during the past year, at the 

 Gloucester laboratory to develop methods for smoking mackerel and 

 storing smoked mackerel under optimum conditions. While smoked 

 mackerel is not what might be called a new product, as it can be 

 obtained in the market at intervals, no extensive trade has been 

 developed in product owing to the fact that it spoils easily during 

 storage. At this writing, a technique has not yet been developed 

 which has promise of commercial application for overcoming this 

 spoilage. However, tests to date indicate that a practical method 

 can be developed. In this connection, it is interesting to note that 

 smoked mackerel can be used to make delicious and appetizing salads. 

 It, therefore, appears that if a practical method can be developed, a 

 new use can be found for this fish which may be of material aid to 

 the mackerel fishery. 



SHRINKAGE OF FRESH FISH PACKED IN ICE 



During the past several years, considerable technical study has 

 been given to the effect of ice when used as a preservative on fresh 

 fish. The importance of this work may be seen from the fact that 

 normally about 600,000,000 pounds of iced fresh fish are shipped to 

 market annually. As a rule, the fish in these shipments are packed 

 in direct contact with the ice. Previous study has shown that 

 this method of icing results in dissipating a large proportion of the 

 mineral salts in the fish, with consequent loss in flavor and food 

 value. This loss is caused by general hydrolysis of the complex 

 protein molecules of the flesh induced by the action of enzymes and 

 bacteria. Thus, the soluble protein and mineral salts are drawn from 

 the fish by the water formed from the melting ice. The actual loss 

 in weight is of little consequence, although it may be as high as 10 

 pounds per ton over a period of 7 days, as further experiments show. 



The present investigation was directed toward learning the effect 

 on the weight of fresh fish when packed in ice. As a result, it was 

 found that other than the loss of the mineral salts, and water soluble 

 proteins, as referred to above, there is no appreciable loss in weight, 

 provided the fish are entirely covered with ice. Apparently, there 

 is an exchange of the mineral salts from the fish with water from 

 the melting ice thereby holding the weight of the fish nearly constant. 

 Thus, while this method of preservation results in little or no actual 

 loss in weight, the flavor may be somewhat impaired. The latter 

 may be corrected by packing the round or dressed fish or cuts there- 

 from in waterproof wrappers before being packed in the ice. 



