Note: Descriptions are shown in the official language in which they were submitted.
CA 02361349 2001-11-09
PROCESS FOR THE EXTRACTION OF LIPIDS FROM FATTY BIRD TISSUES
This present invention relates to a method for the recovery of lipids from
bird
tissues.
Birds possess varying amounts of fat tissue under their skin and in their
peritoneal
cavity. The recovery of the oil or lipids from the lipid containing tissues of
birds is
desirable for various uses such as a nutriment, nutraceutical or cosmetic.
The known methods for recovering lipids from lipid containing tissues of birds
usually comprises the heating of the lipid containing tissues once they have
been removed
from the bird.
In general, the fatty tissues from birds which are raised for food purposes
are
collected in slaughterhouses. Today, fat in generally has a bad reputation and
accordingly it is frequently considered as waste or a low value product. This
reputation
derives in part from the fact that the fats are often contaminated by bacteria
such as
salmonella. Accordingly, often the fats are frequently subjected to a heat
treatment and at
a relatively high temperature to destroy any bacteria. This results in
oxidation of the
unsaturated lipids.
Certain oils derived from certain birds are considered to have a higher value.
Thus, emu oil is taught in the art to have certain desirable characteristics.
One desirable
characteristic of emu oil is that it is particularly low in cholesterol.
It is an object of the present invention to provide a method for the
extraction of
lipids from lipid containing tissues of birds and which preserves the quality
of the lipids.
According to one aspect of the present invention, there is provided a method
for
the extraction of lipids from lipid containing tissues of a member of the bird
species, the
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CA 02361349 2001-11-09
method comprising the steps of comminuting the lipid containing tissues,
placing the
comminuted lipid containing tissues in a solvent for a period of time
sufficient for at least
a portion of the lipids in the lipid containing tissue to dissolve in the
solvent to thereby
provide a liquid fraction and a solid fraction, separating the liquid fraction
from the solid
fraction, and removing the solvent from the liquid fraction to thereby recover
a lipid rich
component.
The method of the present invention may be applied to lipid containing tissues
of
any bird from which it is desirable to recover high quality lipids.
Particularly preferred
are methods supplied wherein the bird is a ratite, a gallinaceous bird or an
anatidae (duck
and geese family). Ratites include the emu, nandou, and ostrich, all of which
have had
oils used for their health benefits by aboriginals in Asia, Africa and South
America.
As practiced commercially, the bird would be bled properly and the fat removed
and cooled. Typically, the fat may be frozen to facilitate the handling of the
tissue.
The step for comminuting the lipid containing tissues may be carried out by
any
conventional means. Thus, one would process the tissues at ambient
temperatures. The
tissues may be comminuted by means of a grinder or other suitable means.
The comminuted lipid containing tissues would then be subjected to extraction
using a suitable solvent. Particularly preferred are acetone and ethyl
acetate. The
extraction would be done at a relatively low temperature and preferably
between 4°C and
25°C. The temperature is not a critical parameter; a higher temperature
will increase the
ambient level of the vapors of the solvent.
The volume/weight ratio of solvent to the lipid containing tissues may vary.
Generally, the solvent tissue volume/weight ratio should be at least 3:1 and a
preferred
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ratio is between 3:1 and 9:1.
Preferably, the solvent tissue mixture is agitated and any suitable means may
be
employed - a container equipped with agitation paddles as is well known in the
art will
ensure an efficient mixing.
The extraction time period may vary; generally, a period of time greater than
20
minutes has been found to be required.
Following, the extraction, the liquid fraction and solid fraction need to be
separated. Again, many apparati are known in the art and to this end, one may
use an
apparatus for centrifuge. Alternatively, filtration could be utilized and in
some instances,
a combination of the methods can be appropriate - i.e. an initial centrifuge
followed by a
filtration. It would also be possible , where time is not a factor, to utilize
sedimentation.
Following the separation of the liquid fraction and the solid fraction, the
solvent
will be removed to provide a lipid rich component. The solvent may be removed
by
known methods, including, for example, flash evaporation, straight evaporation
or spray
drying. The step may be practiced either in batches or on a continuous basis.
The
temperature can be increased up to approximately 125°C for a very
limited period of time.
This will ensure the sterilization of the oils and during a limited period of
time, will
minimize chemical changes in the lipids. To minimize oxidation, one could
perform the
step in a nitrogen atmosphere.
Optionally, one can add an antioxidant to the liquid fraction to minimize
lipid
oxidation. Alternatively, the antioxidant could be added after removal of the
solvent.
Still further, an antioxidant could be added during the extraction step. Any
number of
food grade antioxidants are known in the art.
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Optionally, after separating the liquid fraction and the solid fraction, one
may
wash the solid fraction with a solvent.
Having thus generally described the invention, the following examples
illustrate
embodiments of the invention.
Example 1
Lipid containing tissues from an emu were subjected to an extraction process
wherein the extraction time and the solvent were varied as set forth in Table
1.
TABLE 1
Standardization of the extraction process with emu fat.
Solvent Vol/weight Grinding Time(hours) Yield
acetone 9:1 - 20 3 7.5
ethanol (2"d) 4:1 - 1 2.6
acetone 9:1 - 18 39.6
acetone 9:1 - 18 45.8
acetone 9:1 yes 18 * 61.6
acetone 9:1 yes 18 75.4
acetone 9:1 yes 30 min 38.2
ethyl acetate 9:1 yes 18 87.6
ethyl acetate 9:1 yes 30 min 85.9
ethyl acetate 9:1 yes 30 min 87.4
Chlor:MeOH** 10:1 yes 30 min 78.5
Chlor:MeOH 10:1 yes 30 min 80.0
Experiments were carried out in triplicate and variations between replicates
were
inferior to 5% of the highest value. Experiments were carried out at
4°C. Lipids were
estimated by gravimetry. * Presence of skin with adipose tissues.
* * The method of Folch et al. ( 1957).
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Example 2
Lipid containing tissues of chicken were then subject to extraction as set
forth in
Table 2.
TABLE 2
Extraction of chicken fat
Solvent vol/weight Yield
acetone 9:1 9.8
acetone 9:1 12.5
ethyl acetate 9:1 * 42.2
ethyl acetate 9:1 60.9
Experiments were carned out in triplicate. Variations between replicates were
inferior to 5% of the highest value. The extraction was performed at
4°C, for two hours.
Lipids were estimated by gravimetry. * Presence of skin mixed with adipose
tissues.
Example 3
In this example, freshly ground lipid containing tissue from Peking duck was
immersed in 1/5 of their weight of distilled water at a temperature of
65°C and gently
agitated for 30 minutes while maintaining the temperature constant. Fat was
then
separated from the solid and aqueous base by centrifuge. Volatile matter was
eliminated
by heating for 30 minutes at 130°C under a nitrogen atmosphere. The
yield of lipids as
measured by gravimetry was 50.6%. The experiment was carried out in
triplicate.
Example 4
The lipid containing tissues of the Peking duck of Example 3 were mixed in a
volume/weight ratio of 5:1 with ethyl acetate and were agitated gently for 30
minutes.
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The solvent was evaporated and the lipids measured by gravimetry. The yield
was
67.5%.
'The experiment was repeated with volume/weight ratios of 3:1 and 9:1 and
approximately the same results were achieved.
Example 5
The method of Folch et al, as previously discussed, was carried out on the
same
Peking duck tissue. A yield of 49.9% was achieved.
The lipids recovered in Example 4 were then analyzed and compared with a
commercially refined oil commercially available from Dundee Co. The analysis
is set
forth in Table 4.
TABLE 4
Analysis of emu oil, comparison with commercial refined oil
Specifications Beaudoin-Martin Commercial
Humidity
< 0.05% < 0.05%
Peroxide value 4.0 - 4.4 < 10
Free fatty acids 0.18 < 1.5
Refractive index 1,455 1,456 - 1,467
Iodine values 67 - 89 65 - 85
Saponification values195 - 212 190 - 200
Specific gravity 0.909 0.897 - 0.920
Microbiology col./ml< 10 < 10
Cholesterol (%) 0.04 -
Properties of emu oil are comparable to those of the refined oil on the market
(Dundee Co). Criteria for comestibility of the AOCS are met.
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