96 REPORT OF THE SECRETARY OF COMMERCE 



ology, pharmacologj'^, and general food technology toward the de- 

 velopment of new processes and methods, the salvage of waste prod- 

 ucts, and toward the more complete utilization of the fishery har- 

 vest. Such investigations by the Bureau's technological staff have 

 included the study of many problems in connection with the preserva- 

 tion of fishery products for food, in determining the role of bacteria 

 in preservation and decomposition, in pharmacological studies of 

 the metabolism of the mineral constituents of fishery products, in the 

 preservation of fishery byproducts, in the nutritive value of aquatic 

 products, and in fish cookery. 



Preservation of -fishery products for food. — Studies in this field 

 include an expansion of the knowledge of the chemistry of fish pres- 

 ervation and spoilage, the development of electrometric tests for 

 determining the freshness of various fish, methods for smoking fish, 

 studies of rancidity in fish, the chemical composition of fish proteins, 

 and the development of methods for canning aquatic foods. The 

 problem of the rancidity of the oil or fat in such fatty fish as 

 mackerel has been an acute one wherever it has been necessary to store 

 these fish for any substantial period of time. Various harmless 

 antioxidants are being tested to determine their possible value in 

 preventing or retarding the rancidity which develops in these fish 

 under commercial storage conditions. This work has not progressed 

 to a point where definite recommendations can be made as yet. The 

 electrometric test for determining the relative freshness of fish has 

 been published for haddock and has been worked out for cod and 

 pollock. The importance of fish proteins in the diet is determined 

 by the kinds and amounts of amino acids which make up the chemical 

 composition of such proteins. This work is of fundamental impor- 

 tance and it is hoped that sufficient progress will be made for the 

 issuance of a publication by next year. During the past year the 

 Bureau has published a report on the canning of aquatic foods. 



Bacteriological studies. — These investigations include the develop- 

 ment of disinfectants for sponges for household use, bacteriological 

 examinations of experimentally canned fishery products, and studies 

 of the role of bacteria in the preservation and decomposition of fish. 



Pharmacological studies. — This is a new and extremely interesting 

 investigational field as far as fishery products are concerned. It 

 includes a study of the role of the mineral constituents of fishery 

 products in the metabolism of man and his domestic animals. Sev- 

 eral publications on this work have been issued by the Bureau during 

 the past year, covei;ing the metabolism of arsenic and copper as they 

 occur naturally in fish and shellfish. 



Preservation of fishery byproducts. — The Bureau's technological 

 investigations in this field have been of great value to the agricul- 

 tural industry, as such fishery byproducts as fish oil and fish meal 

 are unexcelled animal feedstuffs. Fish oils and fish-liver oils are 

 not only vitally important as a source of vitamins for use in medi- 

 cine and human nutrition but are essential to the poultry industry 

 as a source of vitamin D to replace the inadequacy of sunshine. Fish 

 meal is a splendid protein concentrate used in mixed feeds for vari- 

 ous farm animals. This product also is used in fertilizers. The work 

 during the past year in this field has consisted in the improvement 

 of methods for manufacturing these products and in the develop- 

 ment of new products. 



