Postmortem role of calpain in Chinese and Wuzong goose muscles

New perspective for Calpain-Mediated regulation of meat Quality: Unveiling the impact on mitochondrial pathway apoptosis in post-mortem

While calpain's role in myofibrillar protein degradation is well-established, its impact on post-mortem apoptosis remains fully elucidated. This study aimed to examine how calpain influences the mitochondrial apoptotic pathway in post-mortem muscle cells and assess its potential impact on chicken tenderness. The findings indicate that the calpain inhibitor treatment could decelerate the rate of lysosome destruction in post-mortem chicken, which is a crucial factor in delaying the mitochondrial apoptotic pathway. Subsequently, this inhibition enhanced the mitochondrial membrane's stability and suppressed the apoptosis-inducing factor Cyt c release into the sarcoplasm. The Western blot results in a greater myofibrillar protein degradation degree in the caspase inhibitor samples compared to the calpain inhibitor samples. Interestingly, the two groups had no significant difference in shear force. Based on these reasons, a novel perspective was introduced in this paper: Calpain could affect the change in meat tenderness by regulating mitochondrial apoptosis in the post-mortem period.

Effects of stepwise chilling with calcium incubation on proteolysis and tenderization in postmortem goose muscle

White Roman goose (12-wk-old male, N = 30) carcasses were obtained from a local government-inspected slaughter plant at approximately ∼10-min postmortem. Each carcass was individually sealed in a zip-lock bag and chilled immediately in a water bath at 15°C for 1 h. Both sides of Pectoralis major muscles were excised from each carcass and incubated in 30 mM CaCl2 or 30 mM EDTA at 15°C for 5 h. After incubation, calcium-incubated and EDTA-incubated breast muscles were vacuum-packaged individually and stored at 5°C for 72 h. Control samples (without CaCl2 or EDTA incubation) were directly vacuum-packaged and chilled in a water bath at 15°C for 5 h and stored at 5°C for 72 h. Muscle specimens were taken from the left side of breast muscles at 1 h of chilling (∼1-h postmortem) and at 5 h of incubation at 15°C (∼6-h postmortem), as well as 24, 48, and 72 h of aging at 5°C for measuring the activities of calpain-1 and calpain-11 as well as the contents of 80 kDa calpain-1 subunit and desmin. The samples of shear force value and myofibril fragmentation index (MFI) were taken from the right side of breast muscle at 24 h and 72 h of 5°C storage. Our results showed that the decrease of the activities of calpain-1 and calpain-11 and the contents of 80 kDa calpain-1 subunit and desmin was more rapid (P < 0.05) in calcium-incubated samples than in control and EDTA-incubated samples. The shear force was lower, but the MFI was higher in calcium-incubated samples than in control and EDTA-incubated samples (P < 0.05). Therefore, our results suggest that the calpain-mediated proteolysis and tenderization in postmortem goose muscle could be greatly enhanced by combine effects of stepwise chilling with calcium incubation at 15°C and thereafter aging at 5°C. With applying this procedure, commercial slaughter plants may have an alternative way to improve the tenderness of goose meat.

Effect of postmortem pH on the physical, biochemical, and sensory characteristics of bovine longissimus thoracis et lumborum muscle

From a large feeding trial study consisting of 299 bulls and steers, 15 carcasses exhibited stress-related syndromes manifested by atypical color and pH which were then selected for subsequent analysis. Samples of longissimus thoracis et lumborum muscle with postmortem pH in the range of 5.5-6.9 were subjected to a 14-day aging period at 2°C. Sensory panel tenderness, connective tissue, juiciness, and flavor intensity of high pH (6.4-6.9) meat were significantly different (p < .05) from samples of intermediate pH (6.0-6.1) as well as normal pH (5.5). Muscles at pH 6.0-6.1 were the toughest samples. This was confirmed by Warner-Bratzler shear force (WBSF), residual force, and myofibril fragmentation index. Palatability attributes of normal pH (5.5) samples were significantly different (p < .05) from dark-cutting beef in terms of tenderness and flavor and at the high pH extreme. The increase in WBSF at pH 6.0-6.1, lack of extensive degradation of muscle proteins, and the decreased sarcomere length resulted in tougher meat than low or high pH muscles. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis of meat at the high pH extreme (6.7-6.9) revealed that the breakdown of troponin-T to 30 kD was complete while at intermediate pH (6.0-6.1) was incomplete. In addition, the appearance of a 'doublet' on high-molecular-weight resolution gels may also account for the greater tenderness experienced by sensory panelists.