FISHERY INDUSTRIES OF THE UNITED STATES, 1934 89 



STUDIES OF TIIIO I)UV1N(; OF NONOILY FISH WASTE 



The studies on effect of inanufacture on the quahty of nonoily fish 

 meals demonstrated the need for more information on a satisfactory 

 dry rendering process. The experimental data obtained as a result of 

 studies in tliis connection have shown that dry reduction can be ac- 

 complished without detrimental "sticking" and "caking" of the 

 gluelikc material in the dryer, if steam pressure and vacuum are 

 maintained at proper levels as drying progresses. From a strictly 

 production standi)oiiit, the greater yield of meal by the dry process 

 counterbalances the less diflicult and apparently lower operating 

 costs of the wet process. When nutritive quality of final products 

 are considered, the dry process has an additional advantage over the 

 wet process. 



UTILIZATION OF SWORDFISH LIVERS 



The work on swordfish-liver oil which was })egun in 1933, to develop 

 a method for the commercial manufacture of this product and thereby 

 make use of a product not fully utilized, was continued during tho 

 past year. On the basis of the data obtained the following conclusions 

 may be drawn: 



Swordfish livers vary in fat content between 15 and 20 percent 

 during the course of the fishing season. The livers do not give up oil 

 readily either by steaming or boiling in water. To obtain efficient 

 oil removal either solvent or improved mechanical extraction methods 

 must be used. 



Depending on the method of extraction, swordfish-liver oil will 

 vary in color from amber to dark brown and from a liquid at room 

 temperature to a solid fat. 



The manner of fat and vitamin storage in swordfish livers is such 

 that the mere extraction of oil does not give efficient vitamin extrac- 

 tion unless conditions are such that the oil comes in intimate contact 

 with the liver tissue. This brings out the role of fat as a vitamin 

 solvent during liver extraction and suggests the possibility of using 

 fish and other oils commercially in extracting vitamins from low fat 

 content livers. 



Solvent-extracted swordfish-liver oils were prepared during the 

 course of the investigation which were 100 times more potent than 

 the U. S. P. standard of reference cod-liver oil, which contains 3,000 

 U. S. P. vitamin A units per gram and 95 U. S. P. vitamin D units 

 per gram. These samples indicate that swordfish-liver oil is the 

 richest known natural concentrate of both vitamins A and D. 



A preliminary report on this investigation has been prepared and 

 as a result of these studies, swordfish livers are now being used in 

 liver-oil manufacture and fishermen are obtaining a new source of 

 revenue from materials formerly discarded. 



HADDOCK-LIVER OIL 



The general results of the Bureau's haddock-liver oil investigation 

 were given in the 1933 report. During the past year these data have 

 been assembled in a form suitable for publication. In last year's 

 report, is was stated that haddock-liver oil corresponded favorably 



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