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The Natural Phenomenon of Separation
of Emu Oil
By: Dr. Ernesto Hernandez - Texas A&M.
Winterization. After several days in storage, emu
oil will develop two layers: a bottom layer of high-melting
stearins and upper layer of lower-melting, more unsaturated
oleins. This phenomenon occurs also in some vegetable
oils. The properties of these two layers in emu oil
have not been studied in depth, but in the case of
oils such as cottonseed, corn or sunflower, the development
of a stearin fraction is considered unsightly. If the
oils are intended to be sold as a crystal clear product,
they are chilled (usually to 40° F), and the stearin
fraction is removed by filtration. The resulting oil
is now devoid of turbidity and is called a clarified
salad oil. In the case of emu oil, this operation can
also be performed if the objective is to produce a
clear product.
The oil resulting from the chilling process will have
a slightly different fatty acid profile.
As mentioned above, emu oil tends to separate into
two distinct phases, a liquid olein fraction and a
semi-solid phase or stearin fraction. The formation
of stearin is due to the presence of saturates (mostly
palmitic acid) in the oil, which, as they agglomerate
into crystals, produce this solid phase. The crystallized
emu oil has a ‘pearly’ white appearance
and the liquid olein is transparent. Table 4 shows
the fatty acid breakdown of these two phases. As expected,
the stearin fraction was richer in the more saturated
fatty acids, namely palmitic and stearic acids and
the olein fraction was higher in oleic and linoleic
acids than in the original oil.
Table 5 shows a profile of how the fatty acids are
actually distributed in the triglycerides. The unsaturated
fatty acids such as oleic acid and linoleic acid tend
to agglomerate in the same triglyceride as illustrated
by the presence of tri- and di-oleates. A triglyceride
profile of cottonseed oil is shown for comparison.
This concentration of unsaturated fatty acids in the
triglycerides also explains why the oils from ratites
readily separate into a liquid and more solid phases.
Table 4. Fatty acid composition profile of emu oil
olein and stearin fractions.
|
Olein |
Stearin |
|
(clear) % |
(solid) |
Myristic (14:0) |
0.35 |
0.38 |
Palmitic (16:0) |
17.6 |
24.6 |
Palmitoleic (16:1) |
2.8 |
3.3 |
Stearic (18:0) |
9.9 |
11.8 |
Oleic (18:1) |
52.6 |
44.6 |
Linoleic (18:2) |
15.2 |
13.4 |
Linolenic (18:3) |
1.0 |
0.52 |
Table 5. Triglyceride profile of emu oil and cottonseed
oil
(P=Palmitic acid; O=Oleic acid; L=Linoleic acid; S=Stearic
Acid).
|
EMU |
Cotton |
|
% |
|
LLL |
7.4 |
15.1 |
LLO |
10.4 |
19.2 |
LLP |
13.5 |
22.4 |
OOL |
13.8 |
4.1 |
POL |
18.3 |
17.4 |
PPL |
5.0 |
7.3 |
OOO |
5.7 |
- |
OOP |
12.7 |
3.0 |
PPO |
6.1 |
2.5 |
PPP |
0.4 |
- |
SOP |
2.9 |
4.5 |
SLS |
2.9 |
- |
PPS |
0.4 |
- |
SOS |
0.5 |
- |
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