Browsing by Author "Silberbauer, Bianca Louise"
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- ItemMeat quality characteristics of giraffe (Giraffa camelopardalis angolensis)(Stellenbosch : Stellenbosch University, 2020-03) Silberbauer, Bianca Louise; Hoffman, Louwrens C.; Strydom, P. E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.ENGLISH ABSTRACT: Although some giraffe populations are threatened, their numbers have been seen to grow exponentially under ranched management conditions. This population growth can be attributed to the absence of natural predators and therefore periodic culling is essential to control their population numbers and thus prevent them from exceeding carrying capacity. These culls result in a large quantity of meat, of which very little is known of the quality. This study aimed to quantify the effect of sex on the yields of fresh cuts from giraffe, and the meat quality thereof as well as the yields and chemical composition of the red offal. For this study sixteen giraffe (Giraffa camelopardalis angolensis) (eight male; eight female) were culled, the majority were relatively young (2½ – 6 years old), however, one female was found to be mature (± 9 years), her data was therefore removed from all analyses except the sensory analysis, to avoid the effect of age. Various body measurements and commercial carcass yields were investigated to quantify the effect of sex there upon. The dead weight and carcass weight was not significantly affected by the sex, however, the males did tend to be heavier (dead weight: males = 691.1 ± 45.47 kg; females = 636.5 ± 33.76 kg; P = 0.096; carcass weight: males = 393.1 ± 28.52 kg; females = 359.5 ± 14.49; P = 0.053). The giraffe were found to have a favourable dressing percentage of ~57 % for both sexes. The foreleg measurements and horn measurements were all larger for the males than the females (P <0.05), despite the relatively young age. The moisture % of the red offal (heart, liver, kidneys and tongue) averaged ~76 %, the protein % averaged ~17 %, the total fat % averaged ~5 % and the ash % averaged ~1 % across both sexes of the giraffe. The red offal had a favourably high protein content as well as a low fat content, which when combined with the high yields thereof per animal, indicates that giraffe offal can serve as a source of low cost protein. The meat yields were investigated, and eight muscles (Longissimus thoracis et lumborum muscle (LTL), Semimembranosus muscle (SM), Biceps femoris muscle (BF), Semitendinosus muscle (ST), Gluteus medius muscle (GM), Supraspinatus muscle (SS), Infraspinatus muscle (IS), and Psoas major muscle (PM)) were removed from each giraffe and the physical meat quality thereof was assessed. The Warner-Bratzler shear force (WBSF) was affected by a significant interaction between sex and muscle (P <0.001), the interaction for the CIE L* values also tended towards significance (P = 0.054). The cooking loss (male = 41.6 ± 0.35 %; female = 40.7 ± 0.33 %; P = 0.024) was found to be higher in males. Muscle had a significant effect on all physical parameters. The ultimate pH of all muscles was in the acceptable range (5.5 – 5.9); the WBSF of all the samples was found to be <43 N which is classified as tender. The meat colour was lighter than most game meat; the myoglobin content of the muscles was found to range from 5.1-9.3 mg/g with a significant interaction between sex and muscle (P = 0.001) with higher myoglobin levels resulting in lower L* values and hue-angles. The chemical composition of the eight muscles was assessed in terms of moisture (77.2 ± 0.09 g/100 g), protein (20.8 ± 0.09 g/100 g), intramuscular fat (IMF) (1.4 ± 0.03 g/100 g) and ash (1.1 ± 0.01 g/100 g). There was a significant interaction between sex and muscle for the moisture (P = 0.044), protein (P = 0.045) and ash (P = 0.042) contents, while muscle (P <0.001) had an effect on the fat content. The mineral content of the bone, liver and LTL muscle was also analysed, the bone was found to have a calcium to phosphorus ratio of 2:1 despite a diet low in phosphorus. The liver and LTL were both high in iron and other essential micro- and macro-minerals. The sensory profile of the LTL muscle of the giraffe as affected by sex was assessed on a 100-point line scale. It was found that the instrumental tenderness of the giraffe meat was considered tough (WBSF >53 N), however, this did not have a strong correlation (r = - 0.616; P = 0.011) with sensory tenderness (~52). The effect of sex was limited, but the males were found to have a higher gamey and metallic aroma, while the females had a higher liver-like flavour than males. The panellists reported to find high intensities of the metallic (~23), sour- (~14) and sweet- (~25) associated and black pepper (~9) attributes of the giraffe meat in this study. The fatty acid profile of the LTL muscles was also analysed and it was found that both sexes had a low intramuscular fat (IMF) content (1.4 - 1.7 %). The polyunsaturated fatty acid to saturated fatty acid (PUFA:SFA) ratios and the n-6:n-3 PUFA ratios as well as the Atherogenicity index were favourable for inclusion in a healthy diet. This study also investigated the effect of post-mortem aging on the tenderness and other physical parameters of the LTL, SM and BF steaks from male and female giraffe in order to determine the ideal ageing period. The tenderness improved until day 22 (19.1 ± 0.30 N) of the 38 day ageing period, after which it plateaued. The colour improved, in terms of redness and saturation, until day 18 (L* = 44.1 ± 0.29; chroma = 22.0 ± 0.15), thereafter discolouration occurred. There was progressive purge loss throughout the ageing period. Therefore, it is recommended to vacuum-age giraffe meat for no more than 18 days.