Post mortem rigor development in the Egyptian goose (Alopochen aegyptiacus) breast muscle (pectoralis): factors which may affect the tenderness

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.

The influence of post-mortem conditioning on the tenderness of Egyptian goose (Alopochen aegyptiacus) breast meat (M. pectoralis major)

BACKGROUND

Egyptian goose breast meat has been found to be very tough compared to the meat of other well-known fowl species. In attempting to clarify the toughness of the meat, the physical and biochemical changes during post-mortem conditioning (14 days) was investigated.

RESULTS

Although there was increased cathepsin (B, B & L and H) activity, together with a decrease (P ≤ 0.05) in myofibrillar fragmentation lengths (32-25 µm) with conditioning, no change (decline) in shear force values was observed. The higher (P ≤ 0.05) shear force of the male breast portions may be linked to the higher (P ≤ 0.05) concentrations of total and insoluble collagen.

CONCLUSIONS

No significant change (decline) in shear force values was observed. Conditioning of Egyptian goose meat as a means of improving the overall toughness cannot therefore not be proposed. The higher shear force and lower sensory tenderness of the male breast portions, as previously observed, may be linked to higher concentrations of total and insoluble collagen.