Masters Degrees (Food Science)

Permanent URI for this collection

https://scholar.sun.ac.za/handle/10019.1/538

Browse

Browsing Masters Degrees (Food Science) by Subject "Animal physiology -- Effect of climate on"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Impact of season on the composition and quality of male and female blesbok (Damaliscus pygargus phillipsi) muscles
    (Stellenbosch : Stellenbosch University, 2012-12) Neethling, Jeannine; Hoffman, Louwrens C.; Britz, T. J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.
    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.