FISHERY INDUSTRIES OF THE UNITED STATES, 1939 227 
utilization becomes more general and as the monetary return to the 
industry increases Several years ago our technologists developed 
methods for producing high quality, “edible salmon oils which could 
be incorporated im canned salmon, thus adding increased nutritive 
value to the canned product and leading to greater uniformity of the 
De This method of utilizing the edible portion of the trimmings 
has become universal practice on the Columbia River and is beginning 
to be adopted more generally throughout the salmon canning industr vy. 
The Bureau’s work has brought about a new development i in salmon 
canning methods which gives a product which is preferred in the more 
critical canned-salmon markets. 
During the past several years the trend in vitamin oil consumption 
has been toward more concentrated products. The Bureau’s studies 
have demonstrated that the visceral portions of the trimmings are a 
more potent source of vitamins than the body trimmings. Since the 
preparation of canning oil requires separation of the edible body 
trimmings from the visceral parts, the latter materials become avail- 
able for ‘utilization in the manufacture of special vitamin pr ee of 
greater potency. Our studies on salmon trimmings have demon- 
strated that oils prepared from total cannery waste norm: uly equal 
and frequently exceed poultry grades of eod liver oil as sources of 
vitamin D. However, in view of the above- mentioned trend toward 
the consumption of more concentrated sources of vitamins, it has 
become necessary to determine whether it would lead to greater 
monetary return to the industry to recover a greater total amount of 
vitamin in total waste cils or to recover a lesser total amount of 
vitamins in the manufacture of the more concentrated visceral oils. 
Studies of this nature are in progress. Attention is being given also 
to the study of equipment suitable for handling small quantities of 
waste which cannot be accumulated at a central reduction plant. 
UTILIZATION OF FISH LIVERS AND VISCERAL ORGANS 
In last year’s report reference was made to a general survey being 
conducted to determine the potential value of the liver and viscera 
from the various species of food fish on the Pacific coast. All work 
contemplated on this project for the present has been completed, and 
the data are being tabulated for publication. 
PREPARATION OF FISH MEALS OF IMPROVED NUTRITIVE VALUE 
During the year the work mentioned in last year’s report dealing 
with the preparation of special dehydrated fish foods was continued in 
cooperation with the Bureau’s Division of Fish Culture and the Uni- 
versity of Washington School of Fisheries. The results demonstrate 
the practicability of conserving special nutritive properties in de- 
hydrated fish waste materials “by low- -temperature drying without 
prior removal of water-soluble extractives. Further work on the 
preparation of fish meals of improved nutritional value is being car- 
ried on in connection with the utilization of salmon cannery trim- 
mings where attention is being directed to the possibility of preparing 
dehydrated products especially high in vitamins A and D, and in 
riboflavin content. 
