Effect of post-mortem time and temperature on bovine intramuscular collagen

A section of longissimus muscle was excised from six steers within 1 h post mortem. Half of the muscle section from each animal was held at 37°C (HT) and the other half was maintained at 1°C (C). Samples were collected from each muscle section in each treatment at 12 and 24 h to study the effect of conditioning temperature and incubation time on collagen properties by comparing the per cent soluble collagen and the relative distribution of collagen components. More of each collagen component (α(1), α(2), β(11) and β(12)) was present on SDS gels of samples incubated for 24 h versus 12 h. Although the collagen solubility did not increase to a great extent in the HT conditioned samples when compared with C samples, the HT treatment increased the effect of post-mortem ageing (i.e. more collagen molecules were solubilised and entered the gel during electrophoresis). Each collagen component, expressed as a percentage of total collagen, remained relatively constant when comparing different temperatures or post-mortem times. This indicates that the increase in collagen components being absorbed on the gels of 24 h post-mortem samples is mainly caused by an increase in the release of total collagen from the connective tissue matrix and not by the specific release of any one component. It was also found that some breakage of collagen crosslinks occurred during high temperature conditioning. No change in type III collagen of intramuscular connective tissue was found in this study.