The underlying mechanisms of the effect of superchilling on the tenderness of beef Longissimus lumborum

This study investigated the effect of superchilling (-30 degrees C until the core temperature achieved-3 degrees C, then stored at-1 degrees C until 24 h, SC) on the tenderness of hot boned beef M. longissimus lumborum (LL), with very fast chilling (-30 degrees C until the core temperature achieved 0 degrees C, then stored at-1 degrees C until 24 h, VFC) and conventional chilling (0- 4 degrees C for 24 h, CC) as the controls. The lowest initial shear force values were obtained in SC samples compared to those from the VFC and CC treatments (P < 0.05). Clear freezing damage of muscle fibers and more myofibril fragmentation were found in SC samples compared with the other samples early post-mortem. Moreover, SC samples showed the highest level of inosine 5-monophosphate at 3 h post-mortem (P < 0.05). A reduced glycolysis rate (as evidenced by lactate content) was also found in SC treated samples suggesting little contri-bution of glycolysis on the tenderization of SC.