Application of proteomic to investigate the post-mortem tenderization rate of different horse muscles.

The research aimed to assess changes on the tenderness and proteolysis of proteins in three different horse muscles as they age after death. The study found that as aging progressed, the meat’s tenderness increased with the most tender muscle being longissimus lumborum. Also, proteomics analysis revealed different patterns of protein breakdown in the different muscles, particularly noticeable after 14 days of aging.

Objective of the Study

• The primary aim of this research was to evaluate how the aging process after death affects the development of tenderness and the breakdown (proteolysis) of proteins in three different horse muscles. Their particular focus was on the myofibrillar proteins, which are the principle muscle proteins involved in the contraction process.

Methodology and Measurements

• The researchers used a measure called Warner-Bratzler shear force to assess meat tenderness. This method is widely used in meat science to objectively quantify the tenderness of cooked meat.
• They also employed a myofibril fragmentation index, another technique to study meat tenderness, which basically measures the fragmentation of muscle fiber. This index significantly increased particularly in the longissimus lumborum (LL) and semimembranosus (SM) muscles throughout the aging time and in the semitendinosus (ST) after 14 days of aging.
• Proteomics analysis was performed to investigate the content and changes in protein structures within the muscles.

Key Findings

• Warner-Bratzler shear force showed decreases during aging across all muscles, with the lowest values found in the LL muscle at all points of sampling. This implies an enhancement in meat tenderness with time.
• In the first phase of aging, proteomic analysis showed that the ST muscle had larger amounts of intact myofibrillar proteins with a high molecular weight.
• After 14 days, a higher accumulation of TnT-derived polypeptides (breakdown product of the protein Troponin T) and spots isoforms ascribed to MLC2 and MLC1 proteins were found. This indicates a more extensive protein breakdown in the ST muscle.
• The results suggest that aging affects meat tenderness and protein breakdown with different intensities in each muscle.

Conclusion

• The findings of this study emphasize that the post-mortem aging process significantly affects meat tenderness and the proteolysis of myofibrillar proteins, with the nature of these effects differing across various muscles. This could be significant for the meat industry, as it could inform decisions about the optimal aging times to produce the most desirable meat texture.