Elucidation of wet aged beef flavor and tenderness phenotypes via untargeted metabolomics

Abstract

The objective of this study was to characterize metabolomic changes in beef M. longissimus lumborum (LL) and exudate (EX) and to evaluate metabolomic shifts based on beef flavor and tenderness phenotype. Beef strip loins were subjected to aging temperature (−2, 0, or 4 °C) and duration (14, 28, 42, and 56 d) regimens. Metabolites were extracted from snap frozen, homogenized LL samples and EX samples using 80 % methanol. Derivatization of metabolites was conducted via methoximation and silylation and analyzed by gas chromatography–mass spectrometry. Slice shear force, proteolytic activity (desmin and troponin-t), free amino acids, and descriptive sensory analysis were also conducted. Agglomerative hierarchical cluster analysis was used to produce tenderness and flavor phenotype groups. The LL metabolome was readily influenced by aging duration, eliciting changes in amino acids, peptides, carbohydrates, biogenic amines, and nucleotides/nucleosides (FDR P < 0.05). An aging temperature × aging duration interaction was observed for nicotinic acid, psicose+tagatose, and tryptamine in EX (FDR P < 0.05). Agglomerative hierarchical cluster analysis resulted in 3 and 4 phenotypic clusters for beef tenderness and flavor, respectively. Tenderness III was characterized by increased SSF and decreased proteolytic activity which coincided with an abundance of carbohydrates (FDR P < 0.05). Flavor IV possessed increased off-flavor intensity which corresponded to an increase of biogenic amines, taste-active amino acids, and organic acids (FDR P < 0.05). Overall, this study characterizes changes in the beef metabolome during aging. Highlights the molecular phenotype of tenderness and flavor, and the potential of exudate to monitor beef quality.