CANNING SARDINES g9 
the changes that take place in frying oil with use appeared to have 
taken place to about the same extent in each case. 
The viscosity of the oils can be laid to oxidation and polymeriza- 
tion changes, and the odor and taste can reasonably be laid to the 
presence of fish oil and to oxidation products of this oil and cot- 
tonseed oil. The cause of the deep red color was assumed to be 
the action of oxygen and heat on sardine oil. To prove this, a 
number of heating tests, in air and away from air, were run on 
cottonseed, Mazola, Crisco, and sardine oils, alone and on mixtures 
of each of the first three with the last. The following results were 
obtained: When heated at 230° in air only the sardine oil darkened 
appreciably, becoming redder in color the longer it was heated. 
Other things being equal, the more surface exposed the darker the 
oil became. All samples became viscous and the acidity increased 
slightly. Sardine oil and mixtures of sardine oil with the other oils 
acquired a color, taste, and odor quite comparable to oils that had 
been used for frying sardines. Samples heated in the absence of 
air were not changed appreciably.” 
MECHANICAL AND CHEMICAL TREATMENT 
Mechanical treatment by washing the oil during the first run of 
frying experiments did not pay for the trouble; the improvements 
were scarcely noticeable. A few of the ordinary methods used in 
purifying oils were tried on fry-bath oil. The methods of treatment 
included fuller’s earth, superheated steam, oxidizing agents, hydro- 
gen according to Schuck’s method, and dilute caustic solution. 
(Experiments described on pp. 167 to170in the Appendix.) All meth- 
ods gave more or less negative results. The caustic treatment im- 
proved the color of the oil but not the taste. This, however, like 
the other chemical methods, is wasteful of oil and expensive to carry 
out. r 
DISCUSSION 
METHODS OF IMPROVEMENT 
There is a big demand for canned sardines that sell at a low price. 
Competition for this business is very keen. In order to help keep 
production costs low, a batch of cooking oil is used much longer 
than it should be. This lowers frying costs, but, as has been shown 
undesirable changes take place in the oil and some of the oil gets 
into the canned product, lowering its quality more or less, according 
to how much use the oil has had. Any improvement in the frying 
procedure that tends to keep the oil in better condition will improve 
the quality of the canned product. 
Betterment can take place along several lines, namely, (1) pre- 
venting or minimizing undesirable changes that take place in the 
oil, (2) treating “old” oil so as to remove its objectionable proper- 
ties, (3) using better suited and cheaper oils for frying, and (4) 
minimizing the amount of frying oil that gets into the can with the 
fish. There is also the possibility of getting around the difficulties 

32 Data on the tests are given in Tables 26 to 28, PP. 168-169. 
83 ** Process for deodorizing fatty oils.’”’ By Ww, , Schuck, Metallurgica] and Chemical Engineering, 
vol. 16, pp. 608-609, New York, 1918, 
