Effect of Ultra-Rapid Prerigor Freezing on Tenderness of Beef Longissimus Dorsi during Storage

To investigate the effect of ultra-fast prerigor freezing on beef quality, beef was subjected to conventional chilling (CC, chilling at 4 ℃), ultra-fast chilling (UFC, chilling at -30 ℃ until the internal temperature dropped to 12 ℃) or ultra-fast freezing (UFF, freezing at -30 ℃ until the internal temperature dropped to -10 ℃) and then stored at (0 ± 2) ℃ until 24 h postmortem. Beef tenderness, water-holding capacity (WHC) and other quality characteristics were measured. The results showed that UFF was more effective in improving beef tenderness during storage when compared with CC and UFC. UFF maintained a higher pH environment by slowing down the decrease in pH, thereby promoting the early degradation of myofibrillar proteins (desmin, troponin-T, and μ-calpain), disrupting myofiber structure, and resulting in elevated myofibril fragmentation index (MFI). These changes had a positive effect in improving muscle tenderness. Meanwhile, UFF reduced the cooking loss but increased the storage loss of beef. Overall, prerigor UFF treatment can improve the tenderness of beef.