Identification of protein markers of muscle fibre type and ageing progress in beef cutaneous trunci and masseter

This study aimed to identify protein markers for fibre type, and extent of post-mortem proteolysis, in bovine cutaneous trunci and masseter, which represent very different muscles types. We applied mass-spectrometry-based proteomic techniques to analysis of muscle fibre type and, examined temporal proteolysis changes with post-mortem ageing. Global proteomic analysis was performed on fresh beef masseter (high type-I fibres) and cutaneous trunci (high type-II fibres). The profile of semi-tryptic peptides, before and after ageing, was analysed to quantify protein degradation extent. Progression of proteolysis in type-I and type-II muscles was indicated by semi-tryptic peptides derived from heat-shock-protein 27, and troponin T fast skeletal muscle, respectively. The content of type I fibres in beef could be estimated using the abundance of myosin light chain-3, and enzymes involved in glycolysis could indicate the content of type-II fibres. These markers could be used in the supply chain to monitor and improve beef quality.