Very fast chilling regulates Ca²⁺ release by maintaining high ryanodine receptor 1 expression to promote meat...

This study aimed to better understand the relationship between Ca²⁺ release and ryanodine receptor 1 (RyR1) expression in porcine muscle under very fast chilling (VFC). Longissimus thoracis et lumborum muscles from fatty Laiwu black and lean Yorkshire pigs were selected as in situ models with low and high RyR1 expression, respectively. Each model was assigned to the control (4 °C/h) and VFC (13 °C/h) treatments. The pronounced sarcomere rupture at the Z lines and a reduction of shear force were observed in the VFC groups, particularly in the high expression model. Ca²⁺ release from the sarcoplasmic reticulum was greater in the high expression model than in the low expression model after VFC, while both were higher than in the control groups. RyR1 level in the VFC-treated low expression model was higher than that of the controls at 1-12 h postmortem. In summary, VFC-mediated maintenance of high RyR1 expression enhances early postmortem Ca²⁺ release, likely contributing to increased microstructural damage and meat tenderization.