Abstract: In order to investigate the effect of caspase-3 on the water retention and tenderness of Tan sheep meat during postmortem aging, the right hind leg meat of Tan sheep was injected with Ac-DEVD-CHO, a caspase-3 inhibitor, or 0.8% NaCl (control group), and aged at 4 ℃. After 0, 6, 12, 24, 48, 96 and 192 h, the activity of caspase-3 and caspase-9, water distribution, degradation of myofibrillar proteins, microstructure and water retention and tenderness indicators were determined. The results showed that with increasing postmortem aging time, the activity of caspase-3 and caspase-9 in the DEVD group was inhibited, and the myofibril fragmentation index (MFI) showed a significantly lower upward trend than the control group (P < 0.05). The pH initially decreased and then increases, and the ultimate pH was lower while the pH at 192 h was higher in the DEVD group than in the control group (P < 0.05). At 24–192 h postmortem, the cooking loss, centrifugal loss, T23 transverse relaxation time and shear force of the DEVD group were distinctly higher than those of the control group. Moreover, during the early postmortem period, the microstructural integrity of muscle in the DEVD group was better than that of the control group. In summary, during the early post-slaughter period (0–24 h), DEVD preserved the integrity of myofibrils and slowed down the process of apoptosis by inhibiting the activity of caspase-3, which resulted in the deterioration of the water retention and tenderness of Tan sheep meat. In the late post-slaughter period (48–192 h), the rise in pH weakened the effect of DEVD, and the consequent rapid activation of caspase-3 accelerated the degradation of myofibrils, thereby improving meat tenderness. Furthermore, the rise in MFI aggravated the collapse of muscle structure, resulting in poor water retention of Tan sheep meat. Overall, the DEVD treatment had a stage-specific effect on the quality of Tan sheep meat during postmortem aging.

Key words: tenderness; water retention; Tan sheep; caspase-3 inhibitor