CANNING SARDINES 169 
TaB_eE 27.—Samples from first set of heating tests on oils used in frying sardines. 
Per cent free fatty acids in samples at end of test } 

















| 
a | Heated sos Heated 
Original | Heated =e Original Heated = 
Sample No. sample sae ae ay Sample No. sample Panes Mele ay 
le ae eos See 0.1 0.7 0.3 Bes ae. cee oe 0.4 0.7 0.5 
a Oe hg ele SR 0.1 0.4 (O53 IE | Le a Se apd 0.4 0.8 0.5 
Gu BA EL Beh 0.3 1.6 0.9 1 fli etl lel oases 0.5 2 0.6 
a me ee Oe ne ee 0.7 1.2 1.0 Slee FT ee See aed 0.4 ON 70 RE ores a 
1 See Table 25 for method of analysis. 
TABLE 28.—Second set of heating tests on oil used in frying sardines } 
{Color comparison of heated oils with oils not heated] 2 
Composition of oil 
sample 
= Sample heated 2 days in Sample heated 2 Sample heated 7 
Sample No. vacuum. days in air days in air 
Cotton “di 
Send Sardine 
| ee sare 20) roa teestoay AMC. ss etek Lepper <P ee. Sammeie th tee: eat £ Slightly darker.’ 
Pe its eh ee hee ee 20 | Very slightly darker________- Reddish== =.= ee Red.! 
3h ee EE ee Se fee 10 10°; (00) Seige toe Bo a teachin the) dc (6 Vay A Sete tit oe Do.6 



1 Samples were placed in 250 cubic-centimeter beakers. This made a shallow layer of oil in each. One 
set of samples was heated 2 days under 25 inches of vacuum at 212° to 240° F. Another set was heated 2 
days, and still another 7 days in air at the same temperature. 
2 All samples were light yellow at the beginning. 
3 Very viscous, having dried to a sticky film. 
4 Not quite as viscous as sample 1. 
5 Not as dark as sample 2. 
6 Not as dark red as sample 4; not quite as sticky a film as in sample 1. 
The action of fuller’s earth and of finely divided carbon from kelp (Kelpchar) 
was tried. Ten per cent of the decoloring material was added, with stirring, 
to the oil, which was kept at 176°. This process was carried out for 15 minutes, 
and then the oil was filtered. It was expected that the decolorizing material 
would remove (by adsorption) the coloring matter dissolved in the oil. This, 
however, was not the case, as the oil was not lightened in color. It was decided, 
therefore, that the color was possibly a molecular characteristic of part of the 
fish oil and not a dissolved pigment. In such a case it would be useless to try 
to remove the color in this manner. 
A sample of partially ‘“‘spent”’ fry-bath oil was kept at 300° to 350° for 2 hours 
while steam was bubbled through it. The oil became darker in color, while the 
taste and odor remained the same. 
About 2 per cent of sodium dichromate, dissolved in a minimum. amount of 
water, was added to partially ‘‘spent’’ fry-bath oil and the whole emulsified. 
A quantity of hydrochloric acid, chemically equivalent to the amount of sodium 
dichromate used, was added to the sodium dichromate solution-oil emulsion and 
the whole thoroughly mixed. The mixture was then heated for a short time at 
130° to 140°. The oxygen liberated in the reaction acted on the oil and its 
impurities, turning the whole very dark in color. Water was then added and the 
whole emulsified. Even standing for several days did not help in breaking the 
muddy emulsion, so further attempts were not made. 
The method used commercially in purifying cottonseed oil was tried. ‘‘Old”’ 
fry-bath oil was emulsified with a slight excess of sodium hydroxide (one-fifth 
normal) over that needed to neutralize the free, fatty acids present. The mixture 
was then heated a little, water added, emulsified, and boiled. Salt (to help in 
breaking the emulsion) was added to the boiling emulsion, after which the mixture 
was placed in a bottle and heated in boiling water until the emulsion was broken. 
Part of the oil was poured off, washed with water, dried, and the improvement 
in color, taste, and odor observed. The taste and odor remained about the same; 
the color, however, was considerably improved. <A second treatment of the 
refined oil improved the color still more. 
