Histological and shear properties of bovine muscle and their alteration during postmortem ageing

A total of 108 longissimus dorsi (LD) and 37 semitendinosus (ST) bovine muscles were utilised to evaluate the cellular changes and interrelationships among histological properties during postmortem ageing. The most important cellular change during postmortem ageing in the LD was an increase in the degree of muscle fibre fragmentation (i.e. reduction in the length of muscle fibre fragments) and in the ST a combination of an increase in degree of muscle fibre fragmentation and a lengthening of the sarcomeres. Degree of muscle fibre fragmentation was the most highly and consistently related histological trait to shear force values and interrelationships of LD histological traits indicated that fibres with larger fibre diameters had shorter sarcomeres and fragmented to a lesser degree. In addition, higher incidences of wavy LD fibres were generally associated with shorter sarcomeres post rigor. In general, histological traits within the ST were interrelated only after 13 days of ageing and histological traits among muscles were generally not significantly interrelated.