Structural changes of costameres and actomyosin induced by postmortem resonant stimulation

Actomyosin and costameres are key determinants of muscle mechanical properties and tenderness. As a mechanical stimulus, resonance may alter tenderness by modulating their structure via postmortem biochemical processes. To explore the responses of costameres and actomyosin and their impact on the mechanical properties of skeletal muscle tissue and meat tenderness under resonance after slaughter. This study investigated the effects of resonance on the main costamere proteins and actomyosin dissociation, leading to alterations in muscle microstructure and thereby enhancing meat tenderness. At 1 h, resonance treatment induced the release of calcium ions, promoted the contraction of actomyosin, and consequently led to a reduction in myofibril diameter, thereby enhancing the mechanical properties of the muscle. However, the dissociation of actomyosin was promoted by resonance at 3 h, reduced the mechanical properties of actomyosin and the stability of its binding interface, damaged the integrity of the endomysium and costameres, and thereby diminished muscle mechanical properties, resulting in improved meat tenderness. These findings provide novel insights into resonance regulation for meat tenderization.