FISHERY INDUSTRIES OF THE UNITED STATES, 1930 117 



Before the era of packaged fish the above fact did not ojffer a prob' 

 lem, since the availability of cod livers greatly exceeded that of had- 

 dock livers. Since that time, however, some of the largest concerns 

 in the ground fishery have grown primarily on trade in packaged had- 

 dock fillets. Thus, within the space of a few years, the domestic 

 supply of livers for liver oil manufacture has turned from cod to 

 haddock. 



In view of the fact that the present domestic demand for cod and 

 cod-liver oil is about 5,000,000 gallons annually, while domestic pro- 

 duction is less than 300,000 gallons, it is considered important that 

 every effort be made to encourage the use of livers suitable for this 

 purpose. However, before progress can be expected, manufacturers 

 must be assured that the possibility of the high iodine number of had- 

 dock liver oil will not detract from the monetary value of the product. 

 Accordingly, during the past year, the bureau made preliminary plans 

 incident to an investigation of this problem which is now under way. 



The scope of the investigation will include a study of the iodine 

 number of haddock liver oil at different seasons of the year from fish 

 caught on the various important fishing grounds. This work will then 

 be correlated with a biochemical study of the oils, and if the results 

 indicate that present specifications are detrimental to the future of 

 haddock liver oils, recommendations will be made in an effort to ob- 

 tain for the product just consideration. 



IMPROVED HANDLING OF FRESH AND FROZEN FISH 



During the year the bureau established a refrigeration laboratory 

 at the Municipal Fish Market in this city for the purpose of continued 

 studies in the evaporation of moisture from frozen fish, the rusting 

 of frozen fish, and the losses incurred through leaching of fish packed 

 in ice. The equipment consisted of a laboratory brine freezer, which 

 employs dry ice as a cooling medium for the brine. The fish are 

 frozen in aluminum pans and molds floated on the brine. The cool- 

 ing is accomplished by placing the dry ice in pans arranged with 

 "fins" on the bottom so as to obtain the maximum surface contact 

 and increase the refrigeration efficiency. In actual practice it was 

 found that 1 pound of dry ice would lower the temperature of 4 

 cubic feet of brine approximately 4° F. The heavily insulated cab- 

 inet around the brine tank renders it possible to hold temperatures 

 as low as 60° below zero F. with a comparatively small quantity of 

 dry ice. 



In addition to this quick freezer, the laboratory was equipped with 

 three electric refrigerators. These were supplied with an oversize 

 unit capable of holding a temperature of 15° below zero F. A speci- 

 all}^ constructed thermostat was arranged so that it would hold the 

 temperature constant within 0.2 of a degree F. These refriger- 

 ators were also equipped with a recording thermometer, which made 

 a continuous record of the temperatures. 



The fish to be studied were first frozen at temperatures of approxi- 

 mately 50° below zero F. These were then coated with hydrogenated 

 cottonseed oil, untreated cottonseed oil, peanut oil, or corn oil; also 

 one sample was water glazed as a control. They were stored at a 

 constant temperature approximating the conditions of commercial 

 storage as nearly as possible. The samples coated with cottonseed 

 oil showed up particularly well, reducing the evaporations from about 



