Very fast chilling modifies the structure of muscle fibres in hot-boned beef loin.

The aim of this study was to gain a better understanding of the tenderisation mechanism associated with very fast chilling (VFC) of beef muscle. Hot-boned striploins from 36 carcasses were allocated to a treatment (control, delayed or immediate chilling below 0°C), and each striploin was divided into three equal portions and allocated to a time post-mortem (2, 5 or 14d). Immediate chilling resulted in lower peak force values at 2d post-mortem and lower particle size after 5d post-mortem. Both chilling treatments significantly improved the WHC by reducing drip loss and cooking loss. Sarcomere lengths were not affected by chilling treatments, although fragmentation and cleavage of muscle fibres were evident along the fibre length, possibly contributing to the reduction in peak force values at 2d post-mortem. Both delayed and immediate chilling resulted in a higher pH at 4 and 24h post-mortem, and colour parameters were modified. These results suggest that VFC has potential for accelerating tenderisation early post-mortem by a combination of biochemical and biophysical effects.