Preliminary analysis of amino acids at various locations along the M. longissimus dorsi in aged beef

Proteolysis of myofibrillar proteins results in an increase in substrate made available for the release of free amino acids. Levels of these amino acids have previously been determined in different muscles over the post mortem ageing period in beef. However, there is a shortage of information available regarding variations within a muscle over this ageing period. The objective of this study was to carry out preliminary investigations into the free amino acid levels in eight locations along the M. longissimus dorsi (LD) over the post mortem ageing period. Free amino acids were analysed in the LD of three Hereford cross heifers at 1 h, 1, 3 and 15 day post mortem. In general most amino acids increased in all locations over the ageing period while a 100% increase was observed in total amino acids averaged over the eight locations. More variations occurred between locations in the earlier post mortem period, however, there were no consistent differences during ageing which might suggest variations in proteolytic activity along the LD. As these analyses were carried out on three animals a larger number of animals would need to be sampled to verify these results.