FISHERY INDUSTRIES OF THE UNITED STATES, 1936 19 
During this same period the smaller fish of this species (approximately 
two-thirds the size of those mentioned above) showed an oil content 
of 9 percent at the beginning of the season, 11 percent in the middle 
of the season, and 9 percent at the end of the season. While the 
above figures represent composite results, there was considerable 
variation in the oil content of individual fish in both groups. The 
extremes of individual variation were from 2 to 30 percent while 
the average individual variation was 6 to 22 percent. 
Samples of the oil from the flesh of Boston mackerel were stored 
at different temperatures to determine, if possible, the temperature at 
which the least rancidity developed. This study to date indicates 
that the lower the temperature the slower the development of rancid- 
ity. It was observed that the oil stored at temperatures below zero 
degrees centigrade showed very little evidence of rancidity, but 
another type of odor and flavor, entirely foreign from fresh oil, re- 
sulted, somewhat similar to a burnt odor or flavor. Simultaneously 
with the development of this odor the oil definitely changed from a 
clear amber to a reddish color. 
As described in last year’s annual report of this Division, the Bureau 
established a cooperative research program with the Musher Foun- 
dation, Inc., New York City, whereby chemists or technologists 
employed by this organization would work on the problem of oxida- 
tion or rancidity in fishery products in the Bureau’s laboratories, 
and under the supervision of the Bureau’s technologists. In connec- 
tion with the preservation of Boston mackerel, the Musher Founda- 
tion had prepared in New England, under the supervision of 5S. R. 
Pottinger of the Bureau’s technological staff, a series of samples of salt 
mackerel packed in barrels and pails. Since our cooperative problem 
with this organization involves the testing of cereal flours as inhibitors 
or antioxidants, two sets of samples were prepared, one set contain- 
ing oat flour and the other packed in accordance with commercial 
practice, without the oat flour. The percentage of oat flour added 
to these samples varied between 2% and 30 percent. In tests of these 
samples at the College Park laboratory for quality, the oat flour ap- 
peared to have a considerable antioxidant effect. However, it was 
found that in repacking the mackerel from barrels to pails no addi- 
tional advantage was obtained by using the oat flour in the brine 
used in the pails. 
The brine solution used in these packs interfered with accurate 
chemical tests to indicate the exact preservative effect of the oat 
flour. However, in actual cooking tests the results thus far indicate 
that the samples of salt mackerel treated with oat flour have a very 
palatable flavor. There was little difference in the appearance of the 
Aa sets of samples. In other words, the oat flour did not detract 
in any way from the pleasing appearance of the treated fish. 
VARIATION IN THE FAT CONTENT OF HALIBUT 
As mentioned in our report for 1935, the reason the bellies of some 
halibut turn bluish and mottled in color when frozen is because of a 
lack of fat storage under the skin. This makes the belly skin more or 
less transparent, when the fish is m j frozen condition. Extreme 
variation in fat content of halibut results in marketing losses and 
may have relation to the biological work of the International Fisheries 
Commission in its study and regulation of the halibut fishery. In an 
effort to determine whether this lack of fatness, which might be 
