Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The objective of this study was to investigate the impact of season on the composition and quality
of male and female blesbok (Damaliscus pygargus phillipsi) muscles (Longissimus dorsi, Biceps
femoris, Semimembranosus, Semitendinosus, Infraspinatus and Supraspinatus). The latter was
quantified on the chemical composition (moisture, protein, fat and ash contents), fatty acid profile,
mineral composition and physical attributes (pH, colour, drip and cooking loss, water holding
capacity and tenderness) of the selected muscles.
All of the blesbok muscles had higher (p<0.01) mean protein contents (20.6 g.100 g-1 to
23.1 g.100 g-1) when the plane of nutrition was believed to be higher (spring of 2009). A strong
negative correlation (r = – 0.82; p<0.01) existed between the moisture and protein contents of the
blesbok muscles. The Longissimus dorsi muscle had the highest (p<0.01) mean intramuscular fat
content (3.4 g.100 g-1) when the plane of nutrition was higher. The chemical composition of the
Longissimus dorsi, Biceps femoris, Semitendinosus and forequarter muscles (Infraspinatus and
Supraspinatus) was affected least by the seasonal differences in the plane of nutrition and activity
levels of the blesbok at the study area. However, season had a larger impact on the chemical
composition of the Semimembranosus muscle.
Season did not have a significant impact on the fatty acid profile of blesbok muscles, but
the difference in the fatty acid profiles between male and female muscles was significant. A
Principal Component Analysis (PCA) bi-plot indicated that female blesbok muscles were
associated with a higher saturated fatty acid (SFA) and mono-unsaturated fatty acid (MUFA)
content. Male blesbok muscles had higher (p<0.01) proportions of total polyunsaturated fatty acids
(PUFA) (40.15 ± 5.39) and polyunsaturated to saturated fatty acid ratios (P:S) (0.85 ± 0.18), in
comparison to female muscles (27.18 ± 8.04 and 0.54 ± 0.20, respectively). Differences in the
anatomical locations of the selected blesbok muscles furthermore influenced the fatty acid profiles.
The less active Longissimus dorsi muscle had higher (p<0.05) total PUFA (38.34 ± 8.62), total
omega-6 (ω6) PUFA (34.46 ± 7.83), total ω3 PUFA (3.44 ± 0.84) and P:S (0.85 ± 0.24) contents, in
comparison to the Infraspinatus muscle (28.96 ± 8.65, 26.23 ± 7.86, 2.31 ± 0.70 and 0.56 ± 0.19,
respectively) and Supraspinatus muscle (28.85 ± 9.23, 26.05 ± 8.24, 2.28 ± 0.76 and 0.55 ± 0.21,
respectively). The hindquarter muscles (Biceps femoris, Semimembranosus and Semitendinosus)
had intermediate fatty acid content.
Season had an impact on the calcium and zinc contents of blesbok muscles. The calcium
content was higher (p<0.05) in the muscles of the animals harvested in spring (6.92 ± 1.94)
compared to winter (5.61 ± 1.79). The zinc content was higher (p<0.05) in the muscles of male
blesbok harvested in winter (4.04 ± 1.70) compared to spring (3.41 ± 1.67). The mineral
composition was furthermore significantly different between the selected blesbok muscles. The
Biceps femoris muscle had the highest (p<0.05) potassium (183.25 ± 12.79), phosphorus (180.21
± 10.36) and magnesium (32.18 ± 1.72) content, while the sodium and calcium content was highest in the forequarter muscles. The Longissimus dorsi muscle had the highest (p<0.05) iron
(3.67 ± 0.51), but significantly lower zinc content (1.63 ± 0.28), in comparison to the forequarter
muscles.
The pH value ≈24 h post mortem was higher (p<0.05) in the Longissimus dorsi muscle of
the animals harvested in spring (5.60) compared to winter (5.54). The CIE a* (14.63 ± 0.86) and
chroma (17.09 ± 0.63) values were higher (p<0.05) for winter than for male blesbok meat in spring
(13.62 ± 1.08 and 16.10 ± 1.03, respectively). The latter values were also higher (p<0.05) for male
compared to female (13.49 ± 0.88 and 16.22 ± 0.98) blesbok meat, at the end of the mating
season (winter). The forequarter muscles had higher chroma values in comparison with the
hindquarter muscles, which had higher (p<0.01) hue-angle values. Season had no influence
(p<0.05) on the drip loss percentages and tenderness of blesbok muscles. The drip loss
percentages were lowest (p<0.05) in the Biceps femoris and Semimembranosus muscles. The
Infraspinatus and Supraspinatus muscles had the lowest (p<0.01) Warner Bratzler shear force
values (20.89 ± 3.23 and 24.90 ± 5.35 N, respectively).
Seasonal differences in the chemical composition of blesbok muscles were statistically
significant. However, these differences were numerically small and it is therefore debatable
whether they are of any biological relevance relating to human nutrition. The differences in the
fatty acid profile and mineral composition as well as the physical meat quality attributes of blesbok
muscles were more attributed to differences in the anatomical locations of the selected muscles, as
opposed to the impact of season or gender. / AFRIKAANSE OPSOMMING: Die doel van die studie was om die impak van seisoen op die samestelling en kwaliteit van blesbok
(Damaliscus pygargus phillipsi) spiere (Longissimus dorsi, Biceps femoris, Semimembranosus,
Semitendinosus, Infraspinatus en Supraspinatus) te bepaal. Die seisoenale impak was
gekwantifiseer op die chemiese samestelling (vog-, proteïen-, vet- en asinhoud), vetsuurprofiel,
mineraal samestelling en fisiese eienskappe (pH, kleur, drup- en kookverlies, water houvermoë en
taaiheid) van die geselekteerde spiere.
Met ʼn hoër voedingspeil (lente 2009) het elkeen van die spiere gemiddeld ʼn hoër (p<0.01)
proteïeninhoud (20.6 g.100 g-1 tot 23.1 g.100 g-1) gehad. ‘n Sterk negatiewe korrelasie (r = – 0.82;
p<0.01) het bestaan tussen die vog- en proteïeninhoud van die blesbokspiere. Met ʼn hoër
voedingspeil het die Longissimus dorsi spier die hoogste (p<0.01) gemiddelde intramuskulêre
vetinhoud (3.4 g.100 g-1) gehad. Seisoenale verskille in die voedingspeil en aktiwiteitsvlakke van
dié blesbokke het minimale verskille in die chemiese samestelling van die Longissimus dorsi,
Biceps femoris, Semitendinosus en voorkwartspiere (Infraspinatus en Supraspinatus) tot gevolg
gehad. Daar was wel seisoenale verskille in die chemiese samestelling van die
Semimembranosus spier.
Seisoen het nie ʼn beduidende invloed op die vetsuurprofiel van die blesbokspiere gehad
nie, maar daar was wel beduidende (p<0.05) verskille tussen geslagte. Soos aangedui deur ʼn
hoofkomponent-analise (PCA) bi-plot, was die spiere van die vroulike blesbokke meer geassosieer
met hoër versadigde en mono-onversadigde vetsuursamestellings. Die spiere van die manlike
diere het hoër (p<0.01) proporsies poli-onversadigde vetsure (PUFA) (40.15 ± 5.39) asook hoër
poli-onversadigde tot versadigde vetsuur verhoudings (P:S) gehad (0.85 ± 0.18) in vergelyking met
die spiere van die vroulike diere (onderskeidelik 27.18 ± 8.04 en 0.54 ± 0.20). Die vetsuurprofiel
van blesbokspiere was ook beïnvloed deur die anatomiese ligging van die spiere. Die minder
aktiewe Longissimus dorsi spier het ʼn hoër (p<0.05) totale PUFA (38.34 ± 8.62), totale omega-6
(ω6) PUFA (34.46 ± 7.83), totale ω3 PUFA (3.44 ± 0.84) en P:S (0.85 ± 0.24) inhoud gehad in
vergelyking met die Infraspinatus spier (onderskeidelik 28.96 ± 8.65, 26.23 ± 7.86, 2.31 ± 0.70 en
0.56 ± 0.19) en Supraspinatus spier (onderskeidelik 28.85 ± 9.23, 26.05 ± 8.24, 2.28 ± 0.76 en
0.55 ± 0.21). Die agterkwartspiere (Biceps femoris, Semimembranosus en Semitendinosus) het
intermediêre vetsuursamestellings gehad.
Seisoen het ʼn invloed op die kalsium- en sinkinhoud van die blesbokspiere gehad. In die
lente het die spiere gemiddeld ʼn hoër (p<0.05) kalsiuminhoud gehad (6.92 ± 1.94), in vergelyking
met dié van winter (5.61 ± 1.79). Die manlike spiere van die blesbokke wat in winter geoes is, het
weer ʼn hoër (p<0.05) sinkinhoud (4.04 ± 1.70) in vergelyking met dié van die lente (3.41 ± 1.67)
gehad. Verder het die mineraalinhoud van die geselekteerde blesbokspiere betekenisvol van
mekaar verskil. Die Biceps femoris spier het die hoogste (p<0.05) kalium- (183.25 ± 12.79), fosfor-
(180.21 ± 10.36) en magnesiuminhoud (32.18 ± 1.72) gehad. Die natrium- en kalsiuminhoud was hoër in die voorkwartspiere. Die Longissimus dorsi spier het die hoogste (p<0.05)
ysterinhoud (3.67 ± 0.51) gehad. Laasgenoemde het ʼn beduidend laer sinkinhoud (1.63 ± 0.28) in
vergelyking met die voorkwartspiere gehad.
Die Longissimus dorsi spiere van die blesbokke wat in die lente geoes is, het gemiddeld
hoër pH-waardes by ≈24 uur post mortem gehad (5.60) in vergelyking met die pH-waardes van dié
spiere in winter (5.54). Die CIE a*- (14.63 ± 0.86) en chroma-waardes (17.09 ± 0.63) van die
manlike blesbokspiere was hoër (p<0.05) in die winter as in die lente (onderskeidelik 13.62 ± 1.08
en 16.10 ± 1.03). Aan die einde van die paartyd (winter) het die manlike blesbokke se spiere ook
hoër (p<0.05) CIE a*- en chroma-waardes as die vroulike blesbokspiere (13.49 ± 0.88 en 16.22 ±
0.98) gehad. Die voorkwartspiere het gemiddeld hoër (p<0.05) chroma-waardes as die
agterkwartspiere gehad, maar laasgenoemde het weer hoër (p<0.01) hue-angle waardes as die
voorkwartspiere gehad. Seisoen het geen effek (p<0.05) op die drupverlies persentasies en
taaiheid van die blesbokspiere gehad nie. Die Biceps femoris en Semimembranosus spiere het
wel die laagste (p<0.05) drupverlies persentasies gehad. Die Infraspinatus en Supraspinatus
spiere het weer die laagste (p<0.01) taaiheid (onderskeidelik 20.89 ± 3.23 en 24.90 ± 5.35) in
vergelyking met die Longissimus dorsi, Biceps femoris, Semimembranosus en Semitendinosus
spiere gehad (onderskeidelik 30.57 ± 6.69, 27.35 ± 3.42, 28.65 ± 4.48 en 31.51 ± 5.63).
Alhoewel daar in die studie statisties beduidende seisoenale verskille in die chemiese
samestelling van die blesbokspiere was, is die verskille numeries klein en is dit debatteerbaar of
dié verskille enigsins biologies van toepassing is op menslike voeding. Verder het die anatomiese
ligging van die geselekteerde blesbokspiere in die studie ʼn groter invloed op die verskille in die
vetsuurprofiel, mineraal samestelling asook die fisiese eienskappe van die spiere gehad, in
vergelyking met die impak van die oes-seisoen en die effek van geslag.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/71826 |
| Date | 12 1900 |
| Creators | Neethling, Jeannine |
| Contributors | Hoffman, L. C., Britz, T. J., Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | x, 104 p. : ill. |
| Rights | Stellenbosch University |
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