The Natural Phenomenon of Separation of Emu Oil Oil Separation
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).
