90 U. S. BUREAU OF FISHERIES 



with U. S. P. specifications for cod-liver oil in every respect except 

 iodine number. The variation with respect to iodine number is not 

 important when unchilled oils are considered. However, during the 

 past year, a new U. S. P. specification has appeared, in which U. S. P. 

 cod-hver oil is designated as a partially destearinized oil. Partially 

 destearinized haddock-liver oils will exceed U. S. P. iodine number 

 specifications in many cases. Therefore, since it is quite generally 

 agreed that haddock-liver oil was meant for inclusion with cod-liver 

 oil and similar liver oils in the class of U. S. P. cod-liver oil, publica- 

 tion of these data should serve as a guide in changing specifications 

 to cover adequately the materials that are supposed to be included 

 under the classification. 



NUTRITIVE VALUE OF AQUATIC PRODUCTS 



Because we are concerned primarily with food products, our 

 nutrition studies are a very necessary and important phase of our 

 technological work. Not only is it essential to determine the food 

 value of fish and shellfish products and byproducts now on the mar- 

 ket, but the relative nutritive value of any experimentally prepared 

 food product is the only true yardstick or standard of measurement 

 for evaluating improvements in methods of manufacture, preserva- 

 tion, handling, and storage of such products. 



During the past year, various phases of the nutrition investigations 

 were carried on, respectively, in the nutrition laboratory in Wash- 

 ington, D. C, wliich in the early fall was moved to College Park, Md., 

 and in the chemical laboratory of the State Medical College at 

 Charleston, S. C, by Charles F. Lee and E. J. Coulson, of the techno- 

 Jogical staff. 



SWORDFISH-LIVER OIL 



In order to evaluate the adequacy of experimental methods for 

 producing oils from swordfish livers, as described previously in tliis 

 report, such oils as manufactured in the laboratory by various methods 

 were tested for their vitamin potency. 



Livers from last season's (1934) catch of swordfish were extracted 

 with a number of difl^erent organic solvents, such as petroleum ether, 

 ethyl ether, ethylene dichloride, carbon tetracliloride, ethyl acetate, 

 acetone, and toluene. Extractions were made of both cooked and 

 uncooked livers. Results thus far indicate that ethylene dicliloride, 

 petroleum ether, and ethyl ether, seem to yield the oil with the highest 

 vitamin potency from both. 



Including samples produced both in 1933 and 1934, the variation 

 in vitamin A potency ranges from 36,000 to 300,000 international 

 vitamin A units per gram. These samples vary in vitamin D potency 

 from 2,850 to 9,500 international vitamin D units per gram. Express- 

 ing it another way, swordfish-liver oil runs as high as 100 times the 

 U. S. P. standard reference cod-liver oil in vitamins A and D. 



SALMON OIL 



Vitamin tests of oils prepared from the trimmings remaining from 

 salmon canning operations, from sahnon eggs, and from salmon livers, 

 were continued during 1934. The oil sami)lcs used in these tests were 



