Efecto de la raza y el tipo de músculo sobre...
Tenderness, along with flavour and juiciness, are crucial quality attributes of beef, as they determine variations in palatability during consumer tasting. These traits ultimately influence the acceptance and value of beef and its derived products. Therefore, research in this field is dedicated to...
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| Formato: | Tesis doctoral acceptedVersion |
| Lenguaje: | Español |
| Publicado: |
Universidad de Buenos Aires. Facultad de Ciencias Veterinarias
2024
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| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_7604 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_7604.dir/7604.PDF |
| Aporte de: |
| Sumario: | Tenderness, along with flavour and juiciness, are crucial quality attributes of beef, as they determine variations in palatability during consumer tasting. These traits ultimately influence the
acceptance and value of beef and its derived products. Therefore, research in this field is dedicated to improve tenderness estimation, reducing variability, and even enhancing these attributes through technological, nutritional, and genetic strategies. In order to achieve this, it is necessary to understand
the biological processes that impact or govern them. Specifically, the focus on tenderness has led to a
detailed investigation of post-mortem muscle proteolysis dynamics. This process is primarily governed by the calpain-calpastatin system, involving the proteolytic action of calpains and their inhibition by
calpastatin.
The bovine calpastatin gene (cast) is intricate due to its three active promoters in skeletal muscle, coupled with alternative splicing and polyadenylation. These gene characteristics result in
significant expression flexibility, giving rise to multiple messenger RNA isoforms. Although some of
these isoforms have been characterized, their precise roles in live animals and the meat maturation process remain elusive. The diverse transcriptional output of this gene not only underscores its substantial impact on tenderness but also positions it as a valuable model for comprehending intricate gene regulation.
Genotype plays a significant role among various factors affecting post-mortem proteolysis. It is well established that meat from Zebu cattle breeds (Bos indicus) is less tender than that from European breeds (Bos taurus), partly due to higher calpastatin activity in the former within the initial
24 hours post-mortem.
Regarding the tenderness variability among different beef muscles, the relative fiber type composition present in them would be linked to proteolysis and, therefore, to their tenderness. Not all
muscles have the same fiber composition, and as a result, they also do not exhibit the same level of tenderness.
Tenderness can be assessed in controlled conditions either through a sensory analysis panel or
indirectly through various methods, such as Warner-Bratzler shear force testing (WBSF) or determination of the myofibrillar fragmentation index (MFI).
In this study, two contrasting bovine breeds, Angus (Bos taurus) and Brahman (Bos indicus), were examined, analysing three distinct muscles in each breed: triceps brachii, semitendinosus, and
infraespinatus. These muscles exhibit pronounced differences in their contractile properties and
represent three commonly consumed cuts. The objective was to scrutinize the relationship between cast gene isoform expression, relative fiber type composition, calpastatin activity, and myofibrillar fragmentation index.
The results indicated disparities in proteolytic potential (higher calpastatin activity and lower myofibrillar fragmentation index) associated with the relative area percentage of fiber types.
Calpastatin activity was more pronounced in the muscle with a higher percentage of type IIX fibers.
Furthermore, differences in cast gene expression were also tied to fiber type. The cast isoforms are likely to contribute differently to tenderness, potentially due to disparities in transcription levels.
Given the variability in calpastatin isoform expression across muscles and breeds, certain epigenetic mechanisms were posited as the source of this variation. Methylation patterns of the cast promoter II found in muscles of both breeds suggest a lack of differences in regions corresponding to
the core promoter, but distinctions were identified within the first exon. Consequently, this epigenetic mechanism could influence transcription and potentially regulate the alternative splicing exhibited by
this gene.
This work offers new insights that enhance our understanding of the molecular mechanisms
involved in the tenderization of beef. The comprehensive analysis of the variables investigated has demonstrated their interconnectedness with beef tenderness, validating the correlation between relative muscle fiber type composition and breed with cast gene expression, and thus, meat proteolytic
potential |
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