CO<sub>2</sub> stunning improved the meat quality by regulating postmortem muscle cell death

The incidence of abnormal meat poses a significant challenge in the meat industry, where stunning serves as a crucial intervention to alleviate pre-slaughter stress and improve meat quality. The underlying mechanisms through which stunning techniques contribute to the divergence in postmortem pork quality are yet to be fully elucidated. This study reveals that the modality of cellular demise in postmortem muscle tissue is modulated by the intensity of pre-slaughter stress and is a determinant of postmortem meat tenderness. The study also investigated the effects of electrical stunning and carbon dioxide stunning on pork quality in Duroc × Landrace × Yorkshire (DYL) pigs. Energy metabolism, muscle fiber structure, and indicators of cell death were measured. The results showed that compared to electrical stunning, carbon dioxide stunning alleviated the depletion of glycogen and ATP, resulting in a lower accumulation of lactic acid. This process induced apoptosis and activated caspase, thereby improving tenderness: shear force values decreased significantly from 47.02 to 42.31 N (<italic>p</italic> &lt; 0.05). ATP treatment caused the reactivation of caspase and increased meat tenderness. This study confirms the efficacy of carbon dioxide stunning in enhancing meat tenderness and provides initial insights into the underlying mechanisms involving energy metabolism and caspase-dependent pathways.