Beef quality, oxidative stability and fatty acid composition of Nguni heifers fed diets with incremental levels of Opuntia ficus-indica (cactus) cladodes
- Authors: Mkhosi, Silungile
- Date: 2020
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18732 , vital:42728
- Description: The objective of the study was to determine meat quality, fatty acid (FA) composition and shelf-life stability of longissimus muscle of Nguni heifers fed incremental levels of Opuntia ficus-indica (cactus) cladodes. A total of 32 heifers aged 36 months were allocated randomly to four dietary treatments: 10% cactus, 20% cactus, commercial and control diets for 90 days. The longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the determination of meat quality, retail shelf-life stability and FA composition. Diet had no effect (P > 0.05) on pH and drip display, however, there was an increase in drip display with ageing time (P ≤ 0.05). Meat colour attributes (L* a* b* and C*) were influenced by diet, with 20% cactus diet having lower L* values compared to other diets (P ≤ 0.05). During a 14-day retail display, a diet day interaction was observed for hue angle with the cactus diets having the lowest values at day 14 of display compared to the other diets (P ≤ 0.05). Differences in meat from heifers fed different diets were observed with 20% cactus accounting for significantly (P ≤ 0.05) higher levels of deoxymyoglobin and the lowest levels of oxymyoglobin. Thawing loss and Warner Bratzler shear force decreased (P ≤ 0.05) with ageing period. Meat from heifers fed cactus diets had lower (P ≤ 0.05) proportions of oleic acid (C18:1n9c) and total MUFA, higher (P ≤ 0.05) proportions of total SFA, C15:1, C17:1, linoleic acid (C18:2n6c) and total PUFA. The control diet produced meat with the highest thiobarbituric acid reactive substances (TBARS) values compared to other diets (P ≤ 0.05) and with ageing TBARS values increased (P ≤ 0.05). Diet showed an effect (P ≤ 0.05) on sensory attributes such as overall tenderness and mouth feel with cactus diets accounting for lower scores. However, juiciness, overall tenderness, grassy and animal like attributes increased with ageing (P ≤ 0.05). Inclusion of cactus in the diet did not produce any adverse effects on meat quality, fatty acid composition, lipid oxidation and sensory quality. Therefore, it can be concluded that inclusion of cactus in Nguni heifer finisher diets up to 20% can improve meat quality.
- Full Text:
- Authors: Mkhosi, Silungile
- Date: 2020
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18732 , vital:42728
- Description: The objective of the study was to determine meat quality, fatty acid (FA) composition and shelf-life stability of longissimus muscle of Nguni heifers fed incremental levels of Opuntia ficus-indica (cactus) cladodes. A total of 32 heifers aged 36 months were allocated randomly to four dietary treatments: 10% cactus, 20% cactus, commercial and control diets for 90 days. The longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the determination of meat quality, retail shelf-life stability and FA composition. Diet had no effect (P > 0.05) on pH and drip display, however, there was an increase in drip display with ageing time (P ≤ 0.05). Meat colour attributes (L* a* b* and C*) were influenced by diet, with 20% cactus diet having lower L* values compared to other diets (P ≤ 0.05). During a 14-day retail display, a diet day interaction was observed for hue angle with the cactus diets having the lowest values at day 14 of display compared to the other diets (P ≤ 0.05). Differences in meat from heifers fed different diets were observed with 20% cactus accounting for significantly (P ≤ 0.05) higher levels of deoxymyoglobin and the lowest levels of oxymyoglobin. Thawing loss and Warner Bratzler shear force decreased (P ≤ 0.05) with ageing period. Meat from heifers fed cactus diets had lower (P ≤ 0.05) proportions of oleic acid (C18:1n9c) and total MUFA, higher (P ≤ 0.05) proportions of total SFA, C15:1, C17:1, linoleic acid (C18:2n6c) and total PUFA. The control diet produced meat with the highest thiobarbituric acid reactive substances (TBARS) values compared to other diets (P ≤ 0.05) and with ageing TBARS values increased (P ≤ 0.05). Diet showed an effect (P ≤ 0.05) on sensory attributes such as overall tenderness and mouth feel with cactus diets accounting for lower scores. However, juiciness, overall tenderness, grassy and animal like attributes increased with ageing (P ≤ 0.05). Inclusion of cactus in the diet did not produce any adverse effects on meat quality, fatty acid composition, lipid oxidation and sensory quality. Therefore, it can be concluded that inclusion of cactus in Nguni heifer finisher diets up to 20% can improve meat quality.
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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
- Authors: Mpala, Bukhosi
- Date: 2020
- Subjects: Meat -- Quality Dairy cattle
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18777 , 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.
- Full Text:
- Authors: Mpala, Bukhosi
- Date: 2020
- Subjects: Meat -- Quality Dairy cattle
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18777 , 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.
- Full Text:
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