Longitudinal vibration interferes with cross-bridge attachment and prevents muscle fibre shrinkage under PSE-like conditions

The impact of longitudinal vibration on cross-bridge attachments between myofilaments was investigated in single fibres and intact muscle. Sinusoidal length vibration (frequency 50 Hz, amplitude 5% of fibre length) reduced active force by 40% when fibres were activated by elevation of [Ca²⁺], but did not alter the force when fibres were in rigor state. When vibrated for 30 min in rigor at pH 5.5 and 38 °C (PSE conditions), the lateral shrinkage of the fibres was significantly reduced, suggesting a potential positive influence of vibration on water-holding capacity. In whole muscle incubated at 38 °C until 8 h post mortem, the progress of rigor onset was accessed by measuring the increase in muscle stiffness. Vibration applied 3-5 h post mortem postponed rigor development, but did not have significant influence on water-holding capacity compared with non-vibrated conditions. In conclusion, the results suggest that muscle vibration can be a future technique to delay rigor development and prevent muscle fibre shrinkage and PSE development after slaughter.

Influence of high pre-rigor temperature and fast pH fall on muscle proteins and meat quality: a review

The impacts of accelerated pH decline combined with high muscle temperature on post-mortem muscle metabolism and subsequent meat quality attributes have been extensively studied. Traditionally, this phenomenon has been observed in pork muscles, primarily due to the relatively fast post-mortem glycolysis rate and its relationships to stress susceptibility of pigs before slaughter. However, the protein-denaturing condition of high temperature/rapid pH fall and subsequent PSE (pale, soft and exudative)-like abnormal meat quality characteristics have been observed in muscles from other species such as beef, lamb, venison and even poultry. Various pre-rigor conditions including the application of electrical stimulation, hot-boning, and/or pre-rigor carcass chilling temperatures in various muscles, in conjunction with carcass stretching/hanging methods, can also contribute to muscle-protein denaturation pre-rigor. This review considers the influence of a faster than normal pH fall at a higher than normal pre-rigor temperature on glycolysis, post-mortem muscle proteins and subsequently meat quality attributes. Gaps in current knowledge are identified and recommendations made for additional research.