XVIII KEPOKT TO THE SECRETARY OF COMMERCE 



IMPROVEMENTS IN METHODS OF HANDLING FRESH FISH 



During the year the bureau established a refrigeration laboratory 

 at the municipal fish market in this city for the purpose of continu- 

 ing preliminary studies on the evaporation of moisture from frozen 

 fish, the rusting of frozen fish, the losses incurred through leaching 

 of fish packed in ice, and the freezing of oysters. In the studies on 

 the evaporation of moisture from frozen fish, the samples of fish 

 were given several different treatments and stored in a constant tem- 

 perature approximating the conditions of a commercial freezer as 

 far as possible. One treatment showed up particularly well, re- 

 ducing the evaporation of moisture from 23 per cent in the untreated 

 fish to 5 per cent in the treated fish. In studying the losses incurred 

 through the leaching of fish packed in ice, preliminary experiments 

 indicated losses of as high as 4 pounds per ton over a period of 7 

 days. This, apparently, is not a great loss until it is multiplied 

 by the amount of fish handled in crushed ice over a period of a year. 

 It then begins to assume proportions which are really surprising. 

 It has been recognized for several years and should be emphasized 

 that these losses represent some of the most important constituents 

 of the fish from a nutrition standpoint, as the leachings contain 

 large quantities of the minerals and a part of the flavor of the fish. 



During the past year experiments have been conducted on freezing 

 oysters. If rapidly frozen oysters could be introduced for consump- 

 tion in the summer months and the public induced to buy them, 

 the annual output of the producers could be materially increased. 

 Our experiments have demonstrated that oysters can be rapidly fro- 

 zen and placed in cold storage for several months without impairing 

 the taste. 



At the time that the above-described experiments were being con- 

 ducted, at the request of the authorities of the District government, 

 our technologist offered suggestions which would tend to increase 

 the attractiveness of the municipal fish market. These dealt with the 

 sanitary conditions, improvements in refrigeration facilities for the 

 stores, and general recommendations. 



BY-rRODUCTS AND PRODUCTION METHODS 



Activities in this section of technology consisted in the comple- 

 tion of studies on the menhaden industry, manufacturing fish oils 

 of higher vitamin potency, cooking and pressing fish, and reduc- 

 tion of nonoily fish waste. 



The menhaden studies disclosed means for the elimination of 

 wastage in the various stages of the factory process, the more 

 efficient operation of machinery, possible improvements in the de- 

 sign of existing machinery, and the introduction of new machinery. 



It has been shown that menhaden press liquors contain approxi- 

 mately 22 per cent of the total solids of the original material, and 

 of this amount about IT per cent is dissolved material and about 5 

 per cent is suspended material. Under present operating condi- 

 tions, all dissolved materials are discarded and only about one- 

 third of the suspended materials are recovered. Yet, by treating 

 press liquors with a chemical coagulant, such as aluminum sulphate. 



