Lipid, cholesterol content and fatty acid composition of ostrich eggs

Lipid, cholesterol content and fatty acid composition of ostrich eggs

Arch. Geflügelk. 1999, 63 (5), 234-236 , ISSN 0003-9098 . ©Verlag Eugen Ulmer GmbH & Co„ Stuttgart
Lipid, cholesterol content and fatty acid composition
of ostrich eggs as influenced by subspecies
Lipid- und Cholesterolgehalt sowie Fettsäuremuster von Straußeneiern
versch iedener Subspecies
J.
0 . Horbanczuk 1,
J.
Sa les 2 ,
J.
1
1
Piotrowski, G . Z i~ba 1, T. Celeda 1, T. Reklew ski and K. Kozaczynski
Manuskri pt eingeg angen am 30. N ovember 1998
lntroduction
Fresh ostrich eggs unsuitable for hatching are used for human consumption on a small scale in certain areas of
South Africa (SALES et al., 1996). In Europe the eating of
an ostrich egg is seen as an exciting and adventurous experience because of its unique appearance in comparison
to other avian eggs normally used for table consumption
(HORBANCZUK, 1998). Little is known about nutritive value
of fresh ostrich eggs for human consumption (REINER
et al., 1995; NOBLE et al., l 996; SALES et al., 1996). With
the expanding of the ostrich indu try outside South Africa
the wild ubspecies Struthio camelus massaicus (Red
Necks) and Struthio camelus australis (Blue Necks) have
became important in breeding programs together with the
traditional farmed subspecies Struthio camelus var. domesticus (HORBANCZU K et al. , 1998). Therefore the present
study was conducted to evaluate the influence of subspecies on the fatty acid composition of fresh ostrich eggs.
Material and methods
Fresh eggs of Red Neck (Struthio camelus massaicus) and
Blue Neck (Struthio camelus australis) ostriches were obtained from birds kept under standard farming condition in
Poland. lmmediately following collection a sample of approximately 5 ml of yolk was obtained, vacuum packed in
plastic bags and stored at -20 °C until analysed. After
solvent extraction of lipids using chloroform-methanol
mixtures (2: 1, v/v) (FOLCH et al., 1957), total lipid was
determined gravimetrically. Total cholesterol of the lipid
fraction was measured by separation using thin-layer chromatography, on silica gel 60G, and read on a UV-visible
spectrophotometer.
An aliquot of the lipid fraction prepared by the Folch
procedure was estrificated with 0.2 ml sodium methylate
at 37 °C for 6 hours and dissolved in 0.2 ml iso-octane.
The resultant fatty acid methyl esters were determined on
a Hewlett Packard 5890 Series II gas chromatograph with
electronic pressure control. An injector temperature of
190 °C, detector temperature of 300 °C were applied. A
standard mixture consisting of free fatty acids (C 16: 0 to
C 22: 6) from Sigma (St. Louis, USA) was analysed daily.
1
Polish Academy of Sciences, Institute of Genetics and Anima!
Breeding, Jastrzebiec, Mrok6w, Poland
2
Department of Anima! Sciences, University of Stellenbosch,
Stellenbosch, South Africa
The individual fatty acid methyl esters were identified by
comparison of the retention times to those of the standard
mixture.
Student's t-test was performed to compare results for total lipid, cholesterol and fatty acid composition between
subspecies.
Results and discussion
Total lipid, cholesterol content and acid composition of the
egg yolks are compared between subspecies in Table l .
Although total lipid differ (P < 0.05) between subspecies,
cholesterol content was similar (P > 0.05). REINER et al.
(1995) has found a value of 31.3 g/100 g for fat extracted
with diethylether from the yolks of eggs from ostriches
where subspecies was not mentioned. Cholesterol values
in the present study are substantially lower than that reported for ostrich yolks by REINER et al. (1995). Values of
11.5 , 13 .0, 14.6, 15.2, 15.6, 16.5, 16.8 and 18. l mg/g yolk
were reported for the cholesterol in eggs from White Leghorn chicken, Rhode Island Red chicken, guinea fowl,
New Hampshire chicken, duck, pea fowl, domestic turkey
and wild turkey respectively (MAURICE et al. , 1994). The
polyunsaturated fatty acids linoleic (18: 2w6) and arachidonic acid (20 : 4w6) differed (P < 0.05) between subspecies, resulting in a higher (P < 0.05) total percentage of
w6-fatty acids in Red Necks (24.34 ± 4.581) than in Blue
Necks (21.74 ± 1.598). However, subspecies did not have
any influence (P > 0.05 ) on total saturated, total monounsaturated, total polyunsatured fatty acids, the ratio between
polyunsaturated and saturated fatty acids or the ratio between w6 and w3 fatty acids. The percentage of palmitic
( l 6: 0) and linoleic acid in the present study differ substantially from values presented by REINER et al . (1995),
leading to differences between studies in the percentages
of total monounsaturated and polyunsaturated fatty acids.
NOBLE et al. (1996) stated values of 28.6 and 8.98% for
palmitic and linoleic acid, respectively, in the triaglycerol
fraction of egg yolk from commercially farmed ostriches
in Zimbabwe. Although the percentage of palmitic acid
was in agreement with values reported for chicken eggs,
values fo und for linoleic acid were substantially higher
(Table 1). Yalues of 8.2 and 16.7% of linoleic acid respectively, were stated for eggs from commercially r~sed
ducks and pheasants (LESKANlCH and NOBLE, 1997). However, it was already presented in 1934 that egg yolk polyunsaturated fatty acids were a reflection of dietary polyunsaturated fatty acids (CRUlKSHANK, 1934). This component
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HORBANCZUK et al. , Lipid, cholesterol content and fatty acid composition of ostrich eggs
235
Table l. Lipid, cholesterol content and fatty acid composition in ostrich egg yolk originating from different subspecies and compared
to chicken egg yolk
Lipid- und Cholesterolgehalt sowie Fettsäuremuster im Dotter von Straußeneiern verschiedener Subspecies im Vergleich zu Hühnereiern
Present study
REINER et al. ( 199 5)
Chicken 1• 2
(n = 7)
Blue Neck
(n = 6)
Red Neck
(n = 6)
27.75 b± 8.745
l 0.80 ± 2.282
29.67° ± 1.824
13.03 ± 1.320
19.8
34.10
13.70
Total
23 .86 ± 1.118
6.43 ± 0.614
30.29 ± l .481
22.70 ± 1.724
6.43 ± 0.975
29.13 ± 1.580
35.7
6.1
43.7
24.5
9.88
Monounsaturated
16: l
18 : l
Total
5.71 ± 0.445
39.70 ± 2.500
45 .41 ± 2.770
5.50 ± 1.075
38.98 ± 4.784
44.48 ± 3.956
8.1
30.6
38.7
47.5
20.42b ± 1.673
0 .88 ± 0 .191
1.32b ± 0 .189
0.24 ± 0 .065
0.84 ± 0.128
23.70 ± 1.712
0.78 ± 0.078
l 1.23 ± 1.436
22.85° ± 4.784
0.82 ± 0.184
1.49° ± 0.525
1.17 ± 0.051
0.99 ± 0.156
26.31 ± 4 .548
0.91 ± 0.194
12.52 ± 2.925
11. l
2.4
11.3
Lipid (g/l 00)
Cholesterol (mg/g)
Fatty acids (%)
Saturated
16:0
18:0
Polyunsaturated
18:2w6
18:3w3
20 :4w6
20:5w3
22 :6w3
Total
Polyunsatured/ satured
w6/w3
0 .22
2 .16
0.47
17.7
0.41
a, b Means between columns for subspecies of ostrich with different superscripts are different (P < 0 .05)
1 ComRltt et al. (1
977)
and N oetE ( 1997)
2 LESKANICH
of egg yolk is thus readily responsive to manipulation
(LESKANICH and NOBLE, 1997; VAN ELSWYK, 1997).
Furthermore, comparisons in fatty acid composition (percentages) between different studies are complicated by the
different individual fatty acids reported.
The conclusion from thi s study is that the cholesterol
content and fatty acid composition of ostrich egg yolk between the subspecies Struthio camelus massaicus (Red
Necks) and Struthio camelus australis (Blue Necks) are
similar. This could be useful in similar marketing strategies of fresh eggs for human consumption. However, before cholesterol values and fatty acid composition could
be used to promote the consumption of fresh ostrich eggs,
values have to be determined on more samples and the
influence of feeding and management have to be investigated, especially because of the possibility of manipulation of the polyunsaturated fatty acids in eggs by dietary
fatty acids. The present study, however, provides valuable
information about the composition of eggs from different
subspecies that could be used for comparison in further
experiments.
Summary
Lipid , cholesterol content and fatty acid compos1t10n of
egg yolks were compared between two subspecies of ostriches. Although total lipid was higher (P < 0.05) in Red
Necks (29.67 g/100 g) than Blue Necks (27.75 g/100 g),
no differences (P > 0.05) were found between subspecies
regarding cholesterol content. The cholesterol values for
ostrich eggs found in the present study is in the lower
range of literature values (11.5 to 18. 1 mg/g yolk) reported
for different avian species. Despite differences (P < 0.05)
Archiv für GeAügelkunde 5/ 1999
in the polyunsaturated fatty acids linolic (Cl8: 2) and arachidonic (C20: 4) acid between subspecies, total saturated,
monounsaturated, polyunsaturated fatty acids and the w6/
w3 ratio did not differ (P > 0.05). Comparisons of fatty
acid composition between literature values from species
are complicated by the fact that polyunsaturated fatty acid
composition of eggs can be readily manipulated by feeding regime.
Keywords
ostrich, eggs, lipids, cholesterol, fatty acids
Zusammenfassung
Lipid- und Cholesterolgehalt sowie Fettsäuremuster von
Straußeneiern verschiedener Subspecies
In der Untersuchung wurde der Lipid- und Cholesterolgehalt sowie das Fettsäuremuster des Dotters von Straußeneiern zweier
verschiedener Subspecies verglichen. Obwohl der Gesamt-Lipidgehalt bei den Red Necks signifikant höher war als bei den Blue
Necks (p < 0,05), wurde kein Unterschied im CholesterolgehaJt
gefu nden (p > 0,05). Der in der vorliegenden Untersuchung ermittelte CholesterolgehaJt der Straußeneier ( 10,8 bis 13,0 mg/g Dotter) ist im Vergleich zum Cholesterolgehalt der Eier anderer Vogelarten ( 1 1,5 bis 18, 1 mg/g Dotter) als niedrig zu bewerten. Es
wurden ferner signifikante Unterschiede zwischen den Subspecies
für die mehrfach ungesättigten Fettsäuren Li.nolsäure (C 18 : 2) und
Arachidonsäure (C20 :4) ermittelt. Allerdings war der Gehalt an
gesättigten (Saturates), einfach ungesättigten (Monoenes) und
mehrfach ungesättigten (Polyenes) Fettsäuren sowie das Verhältnis
von n6/n3 nicht unterschiedlich (p > 0,05). Der Vergleich der Fettsäuremuster mit den Literaturbefunden ist schwierig, da diese
über die Fütterung beeinflußt sei.n können.
236
HoRBANCZUK et al., Lipid, choleslerol content and fatty acid composition of ostrich eggs
Stichworte
Strauß, Eier, Lipide, Cholesterol, Fettsäuren
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Korrespondenzadresse: J. 0 . Horbaiiczuk, Ph.D„ Polish Academy of Sciences, Inst. of
Genetics and Anima] Breeding, Jastrzebiec, 05-551 Mrok6w, Poland,
[email protected]
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