An untargeted and pseudotargeted metabolomic combination approach to identify differential markers to distinguish live from dead pork meat by liquid chromatography–mass spectrometry

An untargeted and pseudotargeted metabolomic combination approach was developed to identify reliable and stable differential markers which can distinguish between pork meat from live pigs conventionally butchered and pork meat from dead pigs butchered immediately after death from diseases or other abnormalities. In this study, 24 differential metabolites of interest were screened by the UHPLC-Triple-TOF-MS-based untargeted metabolomic method, and 14 differential markers were detected by the UHPLC-QTRAP-MS-based pseudotargeted metabolomic method after performing statistical analysis to remove false-positive differential metabolites. Among the possible differential markers identified using the Metlin database and references were carnosine, l-carnitine, l-histidine, N-acetylhistidine, acetylcholine, l-acetylcarnitine and two phosphatidylcholines. The results of the principal component analysis (PCA) and the hierarchical clustering analysis (HCA) indicate that 14 differential markers could be potentially used to distinguish live and dead pork meat. This reliable and stable approach not only could detect the unknown differential markers, but also accurately quantify them.