228 U. S. BUREAU OF FISHERIES 
STORAGE OF FISH MEAL 
As discussed in last year’s report, the tendency for the so-called 
fatty fish meals, that is, those prepared from such fish as pilchard, 
menhaden, salmon, and herring, to heat spontaneously immediately 
following manufacture and during subsequent storage presents one of 
the most aggravating problems of the fishery byproducts industry. 
The spontaneous heating of fish meal necessitates precautionary han- 
dling procedures which increase cost of operation, frequently results in a 
decrease in the quality of the meal, and occasionally causes complete 
loss due to spontaneous combustion. 
During the past year studies have been carried on which demon- 
strate that air- and moisture-proof containers, such as multiwall 
paper bags with asphalt-treated liners, prevent spontaneous oxidative 
heating in fish meal without necessity of the usual precautionary 
handling methods. The multiwall paper containers have the addi- 
tional advantages of resisting insect infestation, preventing sifting of 
the meal during storage and shipment, and practically eliminating the 
fish meal odor of the package. These factors could possibly result in 
obtaining lower transportation rates for fish-meal shipments so packed. 
After 12 months’ storage the only disadvantages of the paper con- 
tainers appeared to be their greater fragility as compared with the 
burlap bag and a very slight increase in the caking of the meal. Tests 
are now underway to determine the upper limit of moisture content 
permissible in meal if it is to be stored in this moisture-proof type of 
container. Should the test results continue as encouraging as those 
obtained to date, and this type of container be adopted by the in- 
dustry, a considerable market would be developed for a domestic paper 
product in place of imported burlap. 
OXIDATION OF FAT IN FISH MEAL 
These studies deal with determining the factors affecting the oxida- 
tion of fats in fish meal under various conditions of processing and 
storage. However, a fundamental attack on the chemistry of fat in 
fish meal had to be pursued in order to get needed information before 
undertaking the more practical aspects of the problem. 
A preliminary study was made with mixtures of solvents in order to 
obtain complete extraction of oils irrespective of degree of oxidation. 
Certain of the resulting data indicate that exposing the meals to light 
and conditions of elevated temperature and moisture produces an 
appreciable oxidation in the constitutive fats or oils. A determina- 
tion of the iodine numbers of some samples of menhaden oil clearly 
indicates that oxidation of the fish oil takes place more rapidly when 
isolated from the meal. <A protein-fat complex in the meal appar- 
ently acts as a natural antioxidant. Pharmacological studies are also 
being carried out with fractions of oils isolated from the various fish 
meals, 
A second study regarding the determination of fat in fish meal was 
continued during the year as time permitted. Much useful data has 
been obtained relative to (a), the effectiveness of various solvents and 
solvent combinations; (b), the relation of different conditions of fish- 
meal manufacture and storage to change in the solubility of the fat; 
and (c), the possibility of differentiating between altered and un- 
altered fat as a means of evaluating the condition of the fat in the meal. 
