Free amino acids and dipeptides in porcine muscles: differences between `red' and `white' muscles.

Three porcine muscles (m. longissimus dorsi, masseter and trapezius), chosen to represent the three main metabolic types, from 18 carcasses had their free amino acids and dipeptides quantified by reverse-phase high performance liquid chromatography (HPLC) in aqueous extracts derivatized with phenyl isothiocyanate. Of the 25 measured compounds, four amino acids and the dipeptide carnosine were closely related to the metabolic type of the three muscles. Masseter, a red oxidative muscle, had the highest contents of aspartic acid, glutamine and taurine. Longissimus dorsi, a white glycolytic muscle was characterised by the highest contents of β-alanine and carnosine. Trapezius, an intermediate muscle, had intermediate contents. These results show that free amino acid and dipeptide contents could partly explain differences in taste of muscles from the same species.