Effect of super-fast freezing before rigor mortis on quality of bovine M. longissimus lumborum.

In order to explore the effects of super-fast freezing (SFF) on beef quality, conventional chilling (CC, 0 ± 2 °C) and very fast chilling (VFC, hot-boned beef loins chilled at -30 °C and then stored at 0 ± 2 °C to bring the temperature down to 0 °C within 5 h post-mortem) were used as controls to investigate the effects of three SFF treatments (-30 °C until the core temperature decreased to -3 °C (SFF-I), -7 °C (SFF-II) and -10 °C (SFF-III), and then stored at 0 ± 2 °C until 24 h post-mortem) on beef tenderness, meat color, water holding capacity, and other related indicators. The results showed that both SFF and VFC improved the tenderness of beef at the early stage of storage compared with CC, and of these SFF-II and SFF-III were the most effective. The SFF has the potential to reduce the cooking loss but increases the purge loss of beef. In addition, SFF has a negative effect on the meat color, but the a* value is still within the acceptable range of consumers. After being treated by SFF, the rate of beef glycolysis was delayed post-mortem. In addition, SFF treatment did not cause a large degree of shortening of sarcomere, but disrupted the muscle fiber structure, contributing to the improvement of muscle tenderness. The results indicate that pre-rigor beef muscles can be deeply frozen, which will not cause obvious shortening with proper freezing and thawing procedures.