86 REPORT OF THE SECRETARY OF COMMERCE 



basic food industries, the develof)ment of better methods for manu- 

 facturing fish meal for use by the agricultural industry, and the 

 discovery of better methods for the preservation and handling of 

 various products of the fisheries. 



Preservation of fishery froducts for food. — These studies have con- 

 sisted of the development of improved methods for handling fresh 

 and frozen fish, improvements in the smoking of fish, methods of 

 canning fish in the home, and the bacteriology of fish preservation 

 and storage. Technologists of the Bureau have developed an electro- 

 metric method for the determination of the relative freshness of fish 

 flesh. They have found that, in order to produce smoked fish of uni- 

 formly high quality, the factors affecting the quality of smoked fish, 

 such as temperature, humidity, volume of smoke, etc., must be con- 

 trolled. Finnan haddie of uniformly high quality were produced 

 experimentally. Methods of home canning fish are being worked out. 

 The changes caused by the action of bacteria are closely related to 

 the chemical changes which accompany enzyme action in the fish 

 flesh. Attempts are being made to correlate the various stages of 

 spoilage with the bacteria count in each of these stages. This has 

 included studies of the bacteriology of the various experimental 

 methods of fish j^reservation described above. 



Preservation of fishe7'y byproducts. — Studies on the improved 

 manufacture of fishmeal from nonoily fish waste demonstrated that 

 by careful control of drier operation this type of material can be 

 converted into a very high-grade meal by a single drying operation, 

 without experiencing appreciable difficulty from glue formation. 

 Material so produced has a particular advantage as a feedstuff in 

 that it possesses considerable vitamin G potency. The effect of 

 dr3dng time and temperature of drying on various factors influenc- 

 ing the nutritive value of fishmeal was determined and additional 

 information was obtained on the relative importance of such factors. 



Data obtained from the examination of a large number of haddock- 

 liver oil samples indicated that oil prepared from livers taken from 

 fish caught during the summer months, especially on Georges Bank, 

 will occasionally have an iodine number which will exceed the maxi- 

 mum upper- limit prescribed for cod-liver oil in the United States 

 Pharmacopoeia. 



At the present time, large quantities of salmon waste are not being 

 utilized. This material is capable of yielding an oil comparable to 

 cod-liver oil in vitamins A and D, and a fishmeal of high feeding- 

 value. In order to assist in increasing the utilization of salmon 

 waste and to improve the product now manufactured, technologists 

 were assigned to the Pacific coast to conduct research on this prob- 

 lem. The results to date, Avhile only of a preliminary nature, indicate 

 the possibility of considerable improvement in the waste-utilization 

 problem of the salmon fishery. 



Studies on the oil extractable from the livers of swordfish taken 

 off the New Flngland coast show that this oil is an even richer source 

 of vitamins A and D than halibut-liver oil. This is an extremely 

 important discovery. 



One method of increasing the usefulness of fish oils is to increase 

 their keeping qualities. Studies are being carried on with the use 

 of antioxidants or inhibitors for the purpose of preventing excessive 

 oxidation and rancidity. 



