Effect of different fat levels and Moringa oleifera leaf meal (MOLM) inclusion on proximate composition, fatty acid profile, lipid oxidation, and sensory attributes of chicken droëwors
- Authors: Tembela, Nelisiwe
- Date: 2020-11
- Subjects: Moringa oleifera , Meat--Quality , Broilers (Chickens)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20893 , vital:46709
- Description: The objective of the study was to determine the effect of different fat levels and Moringa oleifera leaf meal (MLM) inclusion on sensory attributes (aroma, meat flavour, spicy flavour, texture, colour, and saltiness), lipid oxidation, proximate composition, and fatty acid (FA) profile of chicken droëwors. Firstly, sensory attributes of chicken droëwors with different levels of fat and that of Moringa oleifera leaf meal were determined. In the second experiment, the effect of different fat and MLM inclusion levels on lipid oxidation during drying and storage, proximate composition, and fatty acid profile were also determined. A forty randomly selected consumers of different gender and age were used as the sensory panel. 75 percent of lean chicken meat and 25 percent of chicken fat was used during droëwors preparation. Thereafter, 9 treatments of chicken droëwors were produced, with MLM included either at 0 percent, 0.25 percent, 0.5 percent, and fat included at 10 percent and 15 percent. For fatty acid profile, the total lipid from dry sausage of all treatments was quantitatively extracted using chloroform and methanol in a ratio of 2:1. Lipid oxidation was measured by analyzing thiobarbituric acid reactive substances (TBARS) at intervals during drying (0, 0.25, 0.5, 72h) and after 7 days of storage under ambient conditions. The results showed that consumers like the chicken droëwors when 0.5 percent MLM added to the product. The inclusion of MLM in chicken droëwors had a positive effect on consumer sensory. The results of the study demonstrated that chicken droëwors contained a significantly higher percentage (P<0.05) of C18:1c9 (Oleic) (30.95 to 32.65 percent) acid than other fatty acids. Polyunsaturated fatty acids (PUFAs) were all non-significant (P˃0.05) except for Docosahexanoic, which was observed to be significant (P˂ 0.05) in all treatments except T1. There was no significance (P> 0.05) in mono-unsaturated fatty acids (MUFAs), except for Elaidic, vaccenic, linoleic, y-linoleic, erucic, and arachidonic. Lipid oxidation occurred more rapidly (P<0.05) when MLM was not added. During processing and storage, TBARS were higher (P< 0.05) in chicken droewors. TBARS during storage were lower (P>0.05) with MLM added. Results showed a significant difference (P<0.05) in proximate composition of chicken droëwors, containing on average 16.93±1.29 to 10.79± 1.83/ 100 g moisture, 45.80± 1.65 to 67.56± 2.33/ 100 g protein, 14.37± 2.15 to 26.13± 2.15/100 g ash. The current study resultsgave a summary of the composition of chicken droëwors and showed higher susceptibility to lipid oxidation in chicken droewors. Therefore, Moringa oleifera leaf powder showed antioxidant activity in chicken droëwors, reserved lipid oxidation in the product. In conclusion, MLM could be used as a functional antioxidant preservative in chicken droëwors. , Thesis (MSc) (Animal Science) -- University of Fort Hare, 2021
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- Date Issued: 2020-11
Effects of pre-slaughter stress, sex and breed on blood stress indicators, heat shock proteins, glycolytic potential and lamb quality
- Authors: Stempa, Thuthuzelwa
- Date: 2019
- Subjects: Animal welfare , Meat--Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15376 , vital:40402
- Description: The main objective of this study was to determine the effects of pre-slaughter stress (transportation distance and lairage duration), sex and breed on blood stress indicators, heat shock proteins, post-mortem muscle metabolites (glycogen, glucose, glucose-6-phosphate and lactate), glycolytic potential and meat quality attributes from lambs slaughtered at a commercial abattoir. The study was conducted in a high-throughput commercial abattoir in the Buffalo City local municipality of the Eastern Cape Province, South Africa. A total of a hundred eight-month old Dorper and Merino lambs, both male and female, were used in the study. Blood samples for the analysis of glucose and lactate levels were collected using 10.0 mL disposable Becton Dickinson vacutainer tubes treated with fluoride oxalate (grey top) whereas those for determination of cortisol and heat shock protein 70 (HSPA1A) levels were collected using plasma separating vacutainer tubes (SSTTMII, gold top), and those for analysis of creatine kinase and lactate dehydrogenase were collected using 10.0 ml vacutainer tubes treated with Ethylenediaminetetraacetic acid (EDTA). Meat samples (~50 g) for the measurement of post-mortem energy metabolites (glycogen, lactate glucose-6-phosphate and glucose content) were collected from the Muscularis longimissius thoracis et lumborum (LTL) of each carcass ~30 minutes after slaughter and immediately frozen in liquid nitrogen (-196 oC) to prevent further glycolysis. Cold carcass weight (CCW), warm carcass weight (WCW) and carcass fatness (CF) was measured. Meat pH and temperature were measured at iii 45 minutes (initial pH), 6 hours and 24 hours ultimate pH (pHu) post-mortem. Meat colour coordinates [lightness (L*), redness (a*), yellowness (b*), hue angle (H*), chroma (C*)] were also measured 24 hours after slaughter. Furthermore, thawing loss (TL%), cooking loss (CL%) and warner braztler shear force (WBSF) was measured in the LTL 7 days post slaughter. Breed had a significant effect on plasma HSPA1A, plasma lactate, WCW, CCW, L*, muscle glycogen and WBSF. Sex had a significant effect on plasma HSPA1A and pHu. Pearson‘s correlations showed that meat muscle glycogen was positively correlated to glycolytic potential (P<0.001; r=0.63) and initial pH (P<0.05, r=0.20). Muscle lactate was positively correlated to muscle glucose (P<0.01, r=0.30) and glycolytic potential (P<0.001, r=0.79). A positive correlation was shown between muscle glucose and glycolytic potential (P<0.05, r=0.23). The level of LDH was affected by the distance travelled by lambs prior to slaughter. Lairage duration did not affect the levels of CK and LDH. Principal Component Analysis showed a relationship between distance travelled and CK and LDH; and that CK and LDH also influenced the quality of meat from lambs. With respect to sex and breed, the results indicate that female and Dorper were more stressed than male and Merino respectively. Muscle glycolytic potential and post-mortem metabolites have an impact on the quality of meat produced and the Merino had higher muscle glycogen levels at slaughter; hence they produced better meat quality compared to the Dorper. Moreover, no associations were seen between pHu and blood stress indicators. These results indicate that blood stress indicators at exsanguination cannot be used as useful indicators of dark cutting condition in lamb. A relationship between pHu, muscle glycogen and glycolytic potential was established and thus meat pHu can be used as a reliable indicator of tenderness in lamb.
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- Date Issued: 2019