170 U. S. BUREAU OF FISHERIES 
In settling the emulsion separated into three layers. On top was the cloudy 
oil and on the bottom an alkaline solution, very dark in color, appearing as if a 
large part of the color had concentrated there. Between the two layers was a 
small amount of apparently unbroken emulsion. The lower aqueous layer was 
alkaline in reaction, and on addition of acid fatty acids separated out, which were 
chocolate in color. The soap in this alkaline solution was salted out by calcium 
chloride. This cleared the solution and gave a very dark brown-colored soap. 
The removal of color in this case appeared to be adsorption of the colored 
material by the soap solution as it appeared from the emulsion. It might have 
been a case of selective reaction between the hydroxide and the red-colored oil. 
This is in line with the statement given on page 169. The question is an interesting 
one but hard to settle definitely from the information at hand. 
Schuck (see footnote, p. 99) claims that oils that have been burnt in use and 
have absorbed the odor of fish can be sweetened, brightened, and deodorized by 
his process. His method consists of blowing hydrogen for about 20 minutes 
through the oil, which is heated to about 520°. A small amount of hydrogenation 
is claimed to take place. ‘‘Old”’ fry-bath oil was treated in this manner with 
negative results. The oil used was freed from moisture by heating; then it was 
treated. The resulting oil had a burnt taste and odor and was much darker in 
color. It is possible that the procedure was not carried out under as favorable 
conditions as were Schuck’s experiments. It is more probable, however, that 
his claims can not be verified on ‘“‘old”’ fry-bath oil. 
METHODS OF PREPARING THE FISH 
A large number of experiments were made, and almost an equal number of 
packs were prepared during the course of the investigation on methods of pre- 
paring the fish. Storing and shipping tests also. were made with the prepared 
packs. Detailed data covering these experiments, packs, and tests are given here 
in tabular form (Tables 29 to 32). The general discussion upon this work is in 
the main body of this report. 
NOTES APPLYING TO THE TABLES 
Unless otherwise stated in the tables, the fish used were pilchards (Sardina 
cerulea) caught off the coast of southern Claifornia, in good canning condition, 
and of the size ordinarily used for the pound-oval pack. The fish had been scaled 
and the heads and entrails removed before they were prepared for canning. 
Unless otherwise stated, ‘‘brine’’ means a 100 per cent saturated solution of 
salt (sodium chloride) at ordinary air temperature. ‘‘Brined”’ means that the 
fish were immersed in such a solution. 
‘“Dried’”’ means (unless data to the contrary are given) that the fish were 
scattered on a wire flake and subjected to the action of a current of air having a 
temperature of about 100° to 110° and a velocity of about 500 feet per minute. 
“Raw pack’’ indicates that the fish were sealed into the cans without first 
having been cooked. 
Except where statements to the contrary are given, canning consisted of the 
following steps: The prepared fish were packed into pound-oval cans with 
tomato sauce. In the case of fried fish they were allowed to stand overnight 
before being packed into the cans. The product was then exhausted by means 
of “‘live”’ steam or by adding hot tomato sauce. The cans were then sealed while 
hot and processed 11% hours at 240° with steam in a retort. 
In most of the experiments results were checked by comparing the product 
obtained with a similar product prepared by the standard fried-in-oil process. 
