FISHERY INDUSTRIES OF THE UNITED STATES, 1931 107 



(3) a study of tlie cliemical, physical, and biological constants of 

 hadtlook-liver oil and, (4) a study designed to improve the technical 

 usefulness of fish oils. Inasmuch as these investigations are studies 

 of major importance and entail a great amount of experimental work 

 over an extended period of time, it was not possible to bring any of 

 them to completion during the few remaining months of the past 

 year. Accordingly, the following may be considered only as a progress 

 report of the work accomplished at the time of this writing. 



IMPROVED METHODS FOR MANUFACTURING FISH MEAL FROM 

 NONOILY FISH WASTE 



The increasing interest in the use of fish meal as an animal feedstuff 

 makes it highly desirable for the industry to manufacture fish meal of 

 high quality. Fish offal or waste is a perishable material composed of 

 complex inorganic and organic compounds. These latter materials 

 are subject to change during the process of manufacture, and it is, 

 therefore, essential to understand such changes so that those which 

 tend to lower the quality of the products as an animal feed can be 

 eliminated. For this reason, the scope of the investigations on 

 methods of manufacturing fish meal includes studies to determine 

 effect of: (1) Temperature, (2) length of drying time, (3) type of 

 heating medium, and (4) method of appljdng heat on, (a) the nutritive 

 value, (b) the chemical composition, and (c) the appearance of the 

 product. 



In order to carry on the work it has been necessary to: (1) Develop 

 experimental apparatus, (2) conduct tests on such apparatus, (3) 

 test samples for biological value, and (4) make chemical analysis of 

 the finished products. 



The preliminary results obtained to date, while not sufficient to 

 warrant conclusions, indicate that both temperature and length of 

 drying time have a noticeable effect upon the quality of the product. 

 That is, high drying temperatures and long drying periods, within 

 certain limits, detract from the nutritional value of the meal. Inas- 

 much as the elimination of one ordinarily results in the magnification 

 of the other much remains to be done in determining optimum operat- 

 ing conditions. The study of type of heating mediums and methods 

 of applying heat may be expected to aid in the solution of this problem. 

 The biological tests are being carried on in cooperation with the Ohio 

 Agricultural Experiment Station at Wooster, Ohio. 



DEVELOPMENT OF FISH FLOUR SUITABLE FOR HUMAN CONSUMPTION 



In the preparation of certain fish for market, as packaged products, 

 a considerable quantity of material is accumulated which is suitable 

 for human consumption. This material consists essentially of the 

 backbones and the flesh adhering to them. 



In view of recent studies in nutrition, this material constitutes an 

 extremely valuable supplement to the human diet. Nutrition experts 

 are showing the importance of certain mineral elements in the diet; 

 and analysis of fish waste shows that these elements are found in 

 relatively abundant proportion in this material ranging from 6 to 28 

 per cent of minerals. A flour prepared from the edible portion of fish 

 trimmings, therefore, should prove a valuable food product. 



