156 U.S. BUREAU OF FISHERIES 



Test materials were prepared under carefully controlled conditions 

 in a manner so that each factor of manufacture could be measured. 

 The test materials were then submitted to the Ohio Agricultural Ex- 

 periment Station and Cornell University Agricultural Experiment 

 Station, where tests for general nutritive value, digestibility, and 

 vitamin G potency were made. Portions of the same samples were 

 tested chemically in the Gloucester laboratory for the possible de- 

 struction of several essential amino acids which are present in fish 

 protein in limiting amounts. Further, exhaustive engineering studies 

 were carried on to determine the economies of various methods of 

 manufacture. At the present writing the various studies are practi- 

 cally completed, but final conclusions can not be drawn until all 

 phases can be considered collectively. Preliminary data indicate that 

 digestibility, vitamin value, and general nutritive value are afl^ected 

 by drying time, temperature of drying, and method of applying 

 heat, v/liile the essential amino acid, cystine, is affected more by 

 temperature. 



DEVELOPMENT OF FISH FLOUR 



Much of the material now converted into fish meal is suitable for 

 human consumption. This material consists essentially of the back- 

 bones, with adhering flesh, which is accumulated in the preparation 

 of fish fillets. In view of recent studies in nutrition, showing the 

 importance of minerals in the human diet, this material should form 

 the basis of a valuable food product. Further, there is a need for 

 dessicated foods, for special feeding purposes, which could replace 

 the amount of raw foods used, providing the dried product retained 

 essentially the vital factors of the fresh product. Evidence being 

 obtained from the studies on fish-meal manufacture indicate the con- 

 ditions prevailing in what is known as spray of flash drying should 

 yield a product approaching the properties desired for the uses stated 

 above. Studies to date have been concerned with methods of reducing 

 fish waste to a consistency wliich will permit atomization and the 

 development of a suitable apparatus to cause atomization. 



HADDOCK-LIVER OIL 



Fishing companies operating trawlers, catcliing largely haddock, 

 have been concerned with a problem which indicated possible diffi- 

 culty in the marketing of oil for therapeutic use prepared from the 

 livers of the catch. This was due to the fact that the iodine number 

 of haddock-liver oil might be sufficiently high to bring a quantity of 

 oil, running largely haddock, above the maximum iodine number 

 limit of 180 prescribed by the United States Pharmacopoeia. During 

 the past year oils prepared from haddock livers obtained from numer- 

 ous fishing grounds, at varying intervals, have been tested for their 

 physical and chemical constants. In only one of the 30 to 40 samples 

 tested did the iodine number of the crude oil exceed the maximum 

 limit of 180. However, considering the increase of iodine number 

 caused by the removal of the more saturated glycerides during cold 

 pressing, a larger number exceeding the upper United States Phar- 

 macopoeia limit would have been recorded had facilities been availa- 

 ble for satisfactory cold pressing small samples of oil. The significance 

 of this is somewhat confused by the relatively low vitamin values 



