Postmortem calpain changes in longissimus muscle from Lanyu native and Kaohsiung crossbred black pigs.

The purpose of this study was to compare postmortem calpain changes in porcine muscle between Lanyu native (n = 10) and Kaohsiung crossbred (50% Meishan and 50% Duroc, n = 10) black pigs. Longissimus dorsi (LM) muscles (4th to 10th ribs) from both sides of carcasses were hot-sectioned in 30 min postmortem, vacuum-packaged, and stored at 5°C. LM samples from the left side of carcasses were sampled at 0 (30 min postmortem), 3, 6, 12, 24, 48, and 72 h of storage. The 24 and 72 h samples of shear force measurement were taken from the LM at the 8th and 10th ribs of the right side of carcasses, respectively. Our results showed that the decreases in calpain-1 activity, desmin content, and shear force were slower (P < 0.05) in Lanyu native black pig than in Kaohsiung crossbred black pig samples. Therefore, postmortem proteolysis and tenderization were more limited in LM from Lanyu native pigs than from Kaohsiung crossbred pigs.

Calpain activation and proteolysis in postmortem goose muscles.

Meat tenderness is considered as the most important criterion for meat quality by consumers and can be improved by the actions of endogenous proteases, mainly calpains, during postmortem storage at 0-5°C. The purpose of this study, therefore, was to examine the postmortem calpain activation and proteolysis in breast (BM) and leg and thigh (LM) muscles of White Roman goose. BM and LM were taken from goose carcasses (n = 15) at 0 (10-15 min postmortem), 1, 3, and 7 days of storage at 5°C. The decrease in postmortem pH, calpain-1 and -11 activities, and contents of the calpain-1 80 kDa subunit and desmin was more rapid (p < .05) in BM than in LM. Our results show that postmortem proteolysis was more extensive in BM than in LM of White Roman goose, not only because the difference in fiber type composition between two muscles, but because the rate and extent of calpain activation were greater in BM as well. These results may provide useful information to optimize meat processing for different muscles in goose industry.

Postmortem role of calpain in Chinese and Wuzong goose muscles.

The purpose of this study was to compare postmortem proteolysis and tenderization between Chinese and Wuzong goose breast muscles. Four months old Chinese (CG, n = 15) and Wuzong (WZ, n = 15) goose carcasses were vacuum-packaged 10 to 15 min postmortem and stored at 5°C. Breast (Pectoralis major) samples from each carcass were sampled at 0 (∼10 min postmortem), 1, 3, and 7 D of storage. Our results showed that the decrease in pH and calpain-1 activity was not different in CG and WG samples. However, the decrease in calpain-11 activity, desmin content, and shear force were more rapid (P < 0.05) in WZ than in CG samples. Our results indicate that postmortem proteolysis and tenderization of goose breast muscle were more extensive in WZ than in CG goose muscle.

Effect of age on calpain changes in postmortem goose muscle.

Meat tenderization can be affected by a variety of factors including animal age. However, results obtained from goose, chicken, turkey, and ostrich studies have shown that the effects of age on meat tenderization were insignificant, which may be due to a very limited age difference in birds used in those studies. Therefore, the purpose of this study was to investigate the effects of animal age on postmortem proteolysis and tenderization of breast muscle from developing and mature White Roman geese. Goose carcasses from mature (50 mo old, n = 10) and young (3 mo old, n = 10) geese were vacuum-packaged and stored at 5°C within 10 min postmortem. Breast (pectoralis major) samples were taken at 0 (∼10 min postmortem), 1, 3, and 7 D of storage. Our results showed that the decrease in pH, calpain-1 and -11 activities, desmin content and shear force, as well as the increase in myofibrillar fragmentation index were more rapid (P < 0.05) in young than in mature goose breast. These results suggest that postmortem proteolysis and tenderization of goose muscle are extensively affected by age.

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.

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.

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 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.

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.