1.
Influence Of Animal Age, Post-Slaughter Chilling Rate And Ageing Time On Meat Quality Characteristics Of Young Cattle And Buffalo
by Muawuz Ijaz (2010-VA-182) | Dr. Muhammad Hayat Jaspal | Dr. Sher Ali | Dr. Muhammad Yasin Tipu.
Material type: ; Literary form:
not fiction
Publisher: 2017Dissertation note: In Pakistan, livestock contributes 58.6% to agriculture and 11.6% to overall GDP. While, total meat production is 3873 thousand tonsannually from which beef contributes 56% of it. Most of the red meat is being exported to the Middle East countries. Globally, Pakistan is competing with other countries by slaughtering of young animals. Because processor thinks that meat quality is only affected by the age of animal. While, ignores the other factors like post-slaughter chilling rate and ageing time that also affect the meat quality attributes. Therefore, objective of the present study was to investigate the effect of age (18 and 26 months), post-slaughter chilling rate (delayed and rapid) and ageing time (7 days and 14 days) on meat quality traits of M. longissimus dorsi (LD) of cattle and buffalo calves.
In this experiment 48 animals were selected (24 were cattle calves out of which 12 were 18 months and other 12 were 26 months of age; other 24 were buffalo calves out of which 12 were 18 months and other 12 were 26 months of age). After slaughtering, carcasses were splitted into two halves, one for delayed and another for rapid chilling. Temperature and pH were taken at intervals of 0, 1, 2, 4, 7, 18 and 24 hours post slaughter. After overnight chilling and achieving the rigor mortis, both strip-loins were deboned and cut down into nine steaks. Nine strip-loin steaks from each treatment (delayed and rapid chilling) were processed at 1, 7 and 14 days of ageing. Thereafter, striploins were evaluated for meat quality attributes like color, tenderness, purge loss and cooking loss %.
The results of the present experiment showed that cattle age at slaughter showed a significant effect on warner-bratzler shear force (WBSF) values. Bulls with age of 18 months were tender than 26 months of age. Because, collagen starts depositing within muscles as the age of the animal advances, which is a major factor of texture of cooked meat. Meat redness (a*) and chroma (C*) values were higher at 18 months of animal age. While, buffalo meat showed a
non-significant effect of animal age on WBSF values. Moreover, cooking loss percentage was also increased with the advancement of animal age.
In both species, chilling rate significantly affect the WBSF values of LD muscle of 18 months old animals. While, effect of the chilling was non-significant at 26 months of animal age. This could be due to lighter weight and leaner carcasses at 18 months of slaughtering age and were unable to hit the pH/temperature window and faced the cold shortening. Whereas only in cattle calves, hunter L* and a* values were affected by rigor temperature and recorded higher during delayed chilling of carcasses from 18 month old animals. While, chilling rate showed a non-significant effect on cooking loss percentage.
Similarly, in 7 and 14 day aged strip-loin steaks, WBSF values decreased significantly at 18 and 26 month of animals’ age in both cattle and buffalo calves. The rate of tenderization decreased as storage time increased and recorded a 79 and 82 % reduction in WBSF values during first 7 days in meat of cattle and buffalo calves respectively. The improvement in tenderness during storage of steaks could be attributed to the degradation of myofibrillar and associated proteins with help of endogenous protease enzymes. Likewise, all color parameter values were also improved with the storage of meat in 18 and 26 month old animals of both species. In the same way, cooking loss and purge loss percentage values increased linearly with ageing of meat.
CONCLUSION
Based on the findings of the present study it can be concluded that:
There is no obvious difference of meat quality between the animals of 18 and 26 months of age in cattle and buffalo. Thus, instead of early age slaughtering, animals should be raised at least up to two years of age, which may help to increase in overall meat production of the country.
Immediate after slaughtering, rapid chilling of beef carcasses leads to toughening of meat.The effect is more obvious in 18 month old animals in both species. So it is suggested that, pre-chilling or electrical stimulation of carcasses should be exercised rather than rapid chilling in order to elude the chances of cold shortening.
Ageing of striploin steaks improves the tenderness and color of the meat. Effect ismore pronounced during first 7 days of storage. Therefor ageing should be practiced within Pakistan in order to compete globally.Secondly, as beef is being exported by air with high airfreight charges. If this meat is shipped by sea after vacuum packaging at 0⁰C, it may decrease the transportation cost and its ageing will also be done because it takes around 7 days to reach Middle East countries. While in case of other destinations, it will take even more time for shipment.
Availability: Items available for loan: UVAS Library [Call number: 2795-T] (1).
2.
Effect Of Age, Sex And Chilling Method On Meat Quality Traits Of Indigenous Goats
by Muhammad Umair Farid (2010-VA-221) | Mr. Jamal Nasir | Dr. Muhammad Hayat Jaspal | Prof .Dr. Aftab Ahmad Anjum.
Material type: ; Literary form:
not fiction
Publisher: 2017Dissertation note: Agriculture sector of Pakistan is crucial for the economy of the country, livestock constitutes major part of it. Livestock products like meat and milk are important source of protein for the human beings. With the rise in incomes and increasing urbanization, use of animal based protein source is increasing at a faster rate. Mutton in general and goat meat in particular is being preferred by the local consumers as well as by export destinations like Middle East. There are certain quality issues associated with goat meat like discoloration and toughening of meat. These problems are linked with age and sex of animal and processing factors like chilling. As the animal age, sex and chilling rate has significant effect on ultimate goat meat quality parameters like color, cooking loss and tenderness. So it is required to optimize age, sex and chilling rate in order to improve goat meat quality. Present study was designed to investigate the effect of age, sex and chilling regime of goat carcasses.
Animals were procured from Local animal market (mandi) and then slaughtered according to Halal standard method. After slaughtering, carcass were split into two halves longitudinally and one half for delayed and another for rapid chilling. Temperature and pH of the sirloin muscle were measured by inserting pH meter and food grade thermometer. For color determination Minolta® chroma meter was used and for tenderness determination texture analyzer was used.All the collected data was analyzed by using t-test under Complete Randomized Design and level of significance among different interaction were studied by using One Way ANOVA with the help of SAS 9.1. Results showed that,rapid chilling caused sudden fall in temperature but the rate of pH fall was slower than the delayed chilled carcass. After 2hour of slaughtering, rapidly chilled milk teeth animals had lower carcass temperature as compare to two teeth. While in case of sex, female goats had lower carcass temperature in contrast to male. Results revealed that age either
milk or twoteeth animals had non-significant effect on Warner Bratzler Shear Force (WBSF) values. Similarly color measurement also had no effect of age except lightness (L*), which was higher in milk teeth than two teeth animals. Animal sex had no effect on Warner Bratzler Shear Force (WBSF) and color values like lightness (L)*, redness (a*), yellowness (b*), chroma (C*) and hue angle (h). While sex have higher cooking loss % in male as compare to female. Chilling method directly related to the mean tenderness value.As, rapid chilling cause toughness of meat due to the difference in temperature and pH fall as compare to delayed chilling. In case of rapid chilling, mean Warner Bratzler Shear Force (WBSF) values were higher as compare to carcass which were subjected to delay chilling.
Based on the results of the present study, it has established fact that chilling has major effect on the quality of meat. Rapid chilling can lead to cold shortening of meat and as a result the end product could become tougher. While delayed chilling leads to more tender meat. As far as age of the animal is concerned, there is non-significant difference between milk teeth and two teeth goats. It is also common in Pakistan that consumers like to eat mutton from milk teeth and two teeth goats. However, mutton obtained from goats older than two teeth need investigation regarding meat quality. In the same way, exporters are exporting goat carcasses of milk and two teeth animals but the chilling method adopted by processors in not proper. It is common practice that due to shortage of time, processors do not allow the carcasses to stay for pre-chilling and put the carcasses in chillers directly. Ultimately the carcasses lead to cold shortening and consumers’ complaint about the tenderness of the meat. Secondly the age of the goat is directly linked with lightness of meat color, i.e. older animals have higher myoglobin content and this is the reason that older animals have dark colored meat.
Availability: Items available for loan: UVAS Library [Call number: 2796-T] (1).
3.
Comparative Productive And Processing Performance And Fatty Acid Analysis Of Cobb Sasso, Desi And Commercial Broiler Available In Local Market
by Inam ur Rehman (2010-VA-606) | Dr. Muhammad Hayat Jaspal | Dr. Sher Ali | Dr. Waqas Ahmed.
Material type: ; Literary form:
not fiction
Publisher: 2017Dissertation note: Keeping in view the today’s consumer concern, the broiler industry needed a bird having better growth rate as well as resistant to environmental challenges. Cobb Sasso has better livability and may be reared without using antibiotics. Its relatively slow growth may impart better flavor and unique tenderness. This study was conducted at Department of Meat Science and Technology, University of Veterinary and Animal Sciences, Lahore. Total of 48 birds from Cobb sasso, broiler and desi chicken (16 birds per strain and 8 birds per sex) were purchased from local farm and brought to slaughtering facility. After slaughtering, dressing percentage was calculated by removing the feather, shanks, viscera and head. Further, shanks, liver, gizzard, drum sticks, fillets, inner fillets, back, wings, boneless meat and bones percentage was calculated. The pH of muscles was recorded by using pH meter and color by Minolta meter. Tenderness was analyzed by Texture analyzer. Meat sample from breast fillet were used for fatty acid profiling by Gas chromatograph, Flame Ionization Detector (GC-FID). Collected data was analyzed using factorial ANOVA under completely randomized design and means were compared using Fisher’s LSD test. Results showed significantly higher dressing, breast fillets, inner fillets and boneless percentage in broiler while thighs, drumsticks and wings percentages were found significantly higher in cobb sasso. By products shanks, liver, gizzard percentages were higher in desi. pH remained significantly higher in broiler at o hour, 45 minutes and 2 hours of slaughtering. Warner Bretzler Shear force remained highest for desi followed by cobb sasso and broiler which indicates that slow growing birds are tougher. L* was highest for broiler while a* was highest in desi chicken at 2 and 24 hours recorded readings. b* was higher in broiler at 2 hours but after 24 hours its value was higher in cobb sasso although it was not statistically significant. Saturated fatty acids were higher in desi. Mono-unsaturated fatty acids were higher in cobb sasso. Poly-unsaturated fatty acids were non-significant between broiler and desi but significantly low in cobb sasso. Availability: Items available for loan: UVAS Library [Call number: 2801-T] (1).
4.
Influence Of Multiple Freeze Thaw Cycles On Texture And Water Holding Capacity Of Red And White Meat
by Aaqib Khalil (2009-VA-130) | Dr. Sher Ali | Dr. Muhammad Hayat Jaspal | Dr. Haroon Akbar.
Material type: ; Literary form:
not fiction
Publisher: 2017Dissertation note: Freezing has become the preferred choice in the global meat export market. During freezing & thawing, foods are damaged by chemical and physical changes especially during transportation and storage. These freeze-thaw cycles may be repeated several times and cause high drip loss which leads to economic losses. So, multiple freeze thaw cycles damage the meat in rigorous way. Multiple freeze and thaw cycles may have different effects on the water holding capacity and texture of meat which are detrimental for the meat quality
Sixty samples of fresh broiler chicken breasts and sixty samples of beef sirloin was collected from the commercial market. Samples were cut into 10 × 7.5 × 2.5 cmᶟ after cleaning and removal of visible fat and connective tissue from the surface of the samples. Initial data (weighting, pH and color) of all the samples were taken. All the samples were packed into polythene zip bags which wasnon-permeable. Samples (broiler breasts & beef sirloin) were arranged into five groups by random selection. Each group represented each cycle and five cycles were evaluated. Each group contains twelve random sample. First cycle was evaluated on the zero day that was a control group remaining groups were kept in horizontal freezer having -20 C temperature. After four days all samples were thaw at 4 C temperature for 12 hours. After thawing, second group or cycle was evaluated for proposed parameter and remaining three groups/cycles were again subjected to freeze. Every group was evaluated one by one after the period of four days each. Each sample was evaluated for pH, thawing loss, cooking loss, Drip loss, TBARS, meat color and shear force value. The collected data was analyzed by using general linear model under one-way ANOVA. The groups were further analyzed and compared by using post hock test i.e. Tukey test.
This study reveals the effect of different freeze-thaw cycles on physico-chemical changes in red and white meat. This study is helpful to determine the quality and structural changes taking place in red and white meat during different freezing and thawing cycles.
It is recommended to avoid refreezing over and over again. Fast freezing should be used instead of slow freezing for the export of meat. Availability: Items available for loan: UVAS Library [Call number: 2797-T] (1).
5.
Trends in food safety and protection
by Rai, V. Ravishankar | Bai, Jamuna A.
Edition: 1st ed.Material type: ; Literary form:
not fiction
Publisher: UK: CRC Press; 2018Availability: Items available for loan: UVAS Library [Call number: 363.1926 Rai 32703 1st 2018 Meat. Sacience] (1).
