- Title
- Investigating carcass characteristics, meat quality and ageing effects on physicochemical attributes, lipid oxidation, and degradation of muscle proteins in mature beef and dairy cull cows
- Creator
- Mpala, Bukhosi
- Subject
- Meat -- Quality Dairy cattle
- Date
- 2020
- Type
- Thesis
- Type
- Masters
- Type
- MSc (Animal Science )
- Identifier
- http://hdl.handle.net/10353/18777
- Identifier
- vital:42732
- Description
- This study aimed to examine carcass characteristics, meat quality and postmortem ageing effects on physicochemical properties, lipid oxidation and muscle protein degradation in dairy and beef cull cows. Three cattle genotypes representing dairy {Holstein-Friesian (HF)}, beef {Bonsmara (BON)}, and a mixed purpose genotype {South Devon × Aberdeen Angus crossbreed (SD × AA)} were selected at a commercial abattoir lairage and used for this study. From each genotype, mature cows falling into the C-age class were then randomly chosen consisting of 24 HF, 31 BON and 26 SD × AA. The South African red meat classification system was used to evaluate carcass parameters, while objective measurements associated with meat quality {i.e., pH, colour (CIE L*, a*, b*), water holding capacity (WHC) and Warner-Bratzler shear force (WBSF)} were assessed in the M. longissimus thoracis et lumborum (LTL) muscle. Also, six cows were selected from each genotype within a carcass weight range of 290 ± 5 kg and fat score (FS) and conformation score (CS) of 2 and 3 respectively, and their meat was aged in a 4 ℃ chiller for 1, 7 or 14 days. At each ageing period, steaks were evaluated for pH, colour, WHC, WBSF and lipid oxidation. Furthermore, sub-samples were cut from each aged steak, vacuum-sealed, and stored in a freezer at -20 ℃ until needed for the determination of protein solubility and degradation of myofibrillar and sarcoplasmic proteins. Study results showed that the HF had a significantly (P < 0.05) lower dressing percentage than the BON and SD × AA. A total of 59% of the cull cows yielded lean carcasses, while 33% and 4% had a medium and fat subcutaneous fat score, respectively. The Holstein-Friesian recorded carcasses that had a fat score of 0 (2%) and a fat score of 1 (4%) while the Bonsmara had 20% C2, 16% C3 and 2% C4 carcasses, respectively. Most of the carcasses (78%) had a medium CS with the BON and SD × AA making up to 37% and 30%, respectively. All the measured meat quality attributes showed significant differences (P < 0.05) among the three cattle genotypes, except b*, hue angle and thawing loss. Notably, the HF recorded higher (P < 0.05) L*, a* and drip loss values but had a lower WBSF than the BON. The findings of the present study also showed that meat pH, colour traits, purge loss, lipid oxidation, cooking loss and WBSF were significantly (P < 0.05) influenced by post-mortem ageing and genotype. Except for SD × AA, WBSF only showed a significant decrease after 14 days of ageing. Moreover, significant (P < 0.05) ageing and genotype effects were observed on protein solubility and degradation of sarcoplasmic and myofibrillar proteins. One dimensional gel electrophoresis revealed the presence of several protein bands 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper with molecular weights ranges of 16 - 250 kDa and 12.5 – 166.6 kDa in the myofibrillar and sarcoplasmic protein extracts, respectively. The staining intensities of some the protein bands were significantly (P < 0.05) influenced by ageing and cattle genotype. In conclusion, the present study observed that carcass characteristics and meat quality traits vary among cattle genotypes with different production use. The data also revealed that physicochemical characteristics and degradation of muscle proteins is related to both cattle genotype and postmortem ageing. It is recommended that the meat of mature cull cows be aged under vacuum conditions for up to 14 days to improve its tenderness.
- Format
- 134leaves
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
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UFH Department of Livestock & Pasture Science
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details | SOURCE1 | MSc Dissertation Mpala Bukhosi (201705726).pdf | 1 MB | Adobe Acrobat PDF | View Details |