Rong-Ghi R. Chou

Postmortem degradation of desmin and calpain in breast and leg and thigh muscles from Taiwan black-feathered country chickens

BACKGROUND Several studies have reported that the postmortem changes are more rapid in breast muscles (BM) than in leg and thigh muscles (LM) of chickens. However, the reasons for the differences in postmortem proteolysis of BM and LM are still uncertain. The purpose of this study was therefore to compare the postmortem degradation of desmin and calpains in BM and LM from Taiwan black-feathered country chickens at 5 °C. RESULTS The pH was lower (P < 0.05) in BM than in LM. Western blot indicated that postmortem desmin degradation was more rapid in BM than in LM. Casein zymograms showed that at-death µ-calpain activity was higher in BM than in LM. As postmortem time proceeded, µ-calpain was activated and autolyzed more extensively in BM than in LM. However, the µ/m-calpain activity remained stable during postmortem storage in both BM and LM. CONCLUSION Our results suggest that the more rapid postmortem proteolysis found in BM than in LM at 5 °C similar with the previous study could be mainly explained by both greater amounts and faster activation and autolysis of µ-calpain in BM.

Postmortem role of calpains in Pekin duck skeletal muscles.

BACKGROUND It is generally agreed that calpains are involved in postmortem proteolysis of skeletal muscle and improve meat tenderness. However, little information regarding the postmortem role of calpains in duck skeletal muscle is known. Therefore, the purpose of this study was to examine the role of calpains in Pekin duck postmortem breast muscles (BM) and leg and thigh muscles (LM) muscles at 5 °C. RESULTS The postmortem pH was lower (P < 0.05) in BM than in LM. Western blots indicated that postmortem desmin degradation and the 30/32 kDa troponin-T degradation product accumulation were more rapid in BM than in LM. Casein zymograms showed that at-death µ-calpain activity was higher in BM than in LM. As time post mortem increased, µ-calpain was activated and autolyzed more rapidly and extensively in BM than in LM, but µ/m-calpain was activated at a relative slower rate compared with µ-calpain. Correlation results showed that µ-calpain activity, rather than µ/m-calpain activity, in BM samples was highly correlated with the abundance of desmin and the 30/32 kDa troponin-T degradation components across the postmortem period. However, no such correlations were found with LM µ- and µ/m-calpains. CONCLUSION Therefore, our results suggest that BM µ-calpain with a faster and more extensive activation and autolysis would play a relatively dominant role in dictating degradation of desmin and troponin-T in postmortem duck muscle.

Post-mortem Changes in Breast Muscles of Mule Duck

Post-mortem changes in myofibril fragmentation index and degradation of myofibrillar proteins of duck breast muscles at 5°C was investigated. Muscle samples were collected immediately after killing and from the stored carcasses at 5°C for 1, 3, 7, and 14 days post mortem. The results showed that the MFI of the breast muscles increased with time post mortem. SDS-PAGE of myofibrils indicated that the disappearance of troponin-T accompanied concurrently with the appearance of 32-30 kDa components. After 7 days of storage, α-actinin was degraded, and a 98 kDa component appeared. Titin 1 and nebulin also disappeared after post-mortem storage for 3 days.

Effect of lactic or acetic acid on degradation of myofibrillar proteins in post-mortem goose (Anser anser) breast muscle

The effects of lactic acid (LA) and acetic acid (AA) on changes in myofibrillar proteins of post-mortem goose breast muscle marinated for 24 h at 5 °C were studied. Purified myofibrils were prepared from 0.1 M LA or AA samples and controls (non-marinated samples) after 0, 1, 3, 7 or 14 days of storage at 5 °C. The changes in myofibrillar proteins of goose muscle were examined by SDS-PAGE. Goose breast muscle marinated in LA and AA exhibited degradation of myosin heavy chains. The appearance of ∼95 and ∼27 kDa components and the disappearance of titin and nebulin were also more rapid than for control muscle. These results suggest that acid marination enhanced the post-mortem proteolysis of goose breast muscle. © 2000 Society of Chemical Industry

μ-Calpain is involved in the postmortem proteolysis of gizzard smooth muscle.

Postmortem changes in proteins that have been implicated in affecting muscle integrity were examined in goose (GG) and duck (DG) gizzard smooth muscle stored at 5°C. GG and DG smooth muscles were sampled at 0, 1, 3 and 7 day of storage. The pH was approximately 7 in both GG and DG samples during postmortem storage. Casein zymograms showed that 0-day μ-calpain activity was higher (p<0.05) in GG than in DG samples. As postmortem time progressed, μ-calpain was activated and autolyzed more extensively in GG than in DG samples. However, μ/m-calpain remained relatively stable in both samples. Western blots indicated that postmortem desmin degradation was more rapid in GG than in DG samples. In contrast, α-actinin remained nearly unchanged in both samples. Therefore, our results suggest that μ-calpain has an important role in the postmortem proteolysis of gizzard smooth muscle.

Postmortem calpain changes in ostrich skeletal muscle.

The objective of this study was to study the postmortem calpain change in ostrich muscle. Iliotibialis cranialis and Obturatorius medialis muscles were removed from the both sides of carcasses (n=8). The muscles from the left side were sampled after 0, 1, 2, 3, and 7days of storage at 5°C, while the right-side muscles were taken at 1-, 3-, and 7-day postmortem for shear force measurements. The results showed that the calpain-1 activity was not detected in ostrich muscle during the entire 7-day postmortem storage period, while the calpain-11 was. The unautolyzed calpain-11 activity decreased and the autolyzed calpain-11 activity increased with time postmortem. Desmin content and shear force did not change during postmortem storage although a minor degradation of desmin was observed. Therefore, our results suggest that limited postmortem proteolysis (as suggested by the limited degradation of desmin) and tenderization might be due to the lack of calpain-1 and/or insufficient calpain-11 activity present in ostrich muscle.

Comparison of postmortem proteolysis between Pekin and Muscovy duck breast muscles.

BACKGROUND Duck muscle is a popular source of red meat in Asia. However, information regarding the postmortem proteolysis of skeletal muscle between duck species is very limited. Therefore, the purpose of this study was to compare the postmortem calpain and desmin degradations between Pekin (PD) and Muscovy (MD) duck breast muscles stored at 5°C. RESULTS The pH and μ/m-calpain activity were not different (P > 0.05) between PD and MD postmortem muscles. However, μ-calpain activity and desmin content decreased more rapidly (P < 0.05) in PD than in MD samples. CONCLUSION Therefore, our results suggest that the postmortem proteolysis is more rapid and extensive in breast muscle from PD compared to MD.

Postmortem role of calpain-11 in ostrich skeletal muscle

The postmortem calpain-11 role in ostrich muscle was investigated. Pairs of ostrich muscle (Iliotibialis cranialis) were excised from 32 ostrich carcasses in 3-h postmortem and randomly assigned into four treatments. The muscle was cut into 2.5-cm thick meat cores. The cores were incubated in 30 mM CaCl2, 30 mM EDTA, 90 mM NaCl, or control. The cores from the left-side carcasses were sampled after 0, 1, 2, and 3 days of incubation at 5 °C, while the right-side meat cores were taken at 1-day and 3-day incubation for shear force measurements. The results showed that the decrease in unautolyzed and total activities of calpain-11, desmin content and shear force was more rapid in CaCl2-incubated samples than in control, NaCl- and EDTA-incubated samples. Thus, present results suggest that in the absence of calpain-1, calpain-11 with an extensive activation by adding exogenous Ca2+ could enhance the postmortem proteolysis and tenderization of ostrich muscle.

Post-mortem proteolysis and tenderisation are more rapid and extensive in female duck breast muscle

Abstract The post-mortem proteolysis and tenderisation between male and female duck breast muscles were compared. The results showed that μ-calpain activity, desmin content and shear force decreased more quickly in female than in male samples stored at 5°C. It is suggested that the post-mortem proteolysis and tenderisation are more rapid and extensive in female duck breast muscle.