Comparative Profiling of Free Amino Acids, Free Fatty Acids, and Volatile Organic Compounds in the Longissimus Thoracis Muscle of Three Sheep Breed Groups

This study investigated breed-related differences in the flavor chemistry of the longissimus thoracis muscle from Cele Black sheep (CLH), Australian White × Hu crossbred sheep (AH), and Hotan sheep (BDT). Eighteen yearling rams (six animals per group) were evaluated. Free amino acids (FAAs) were quantified by LC–MS/MS, and free fatty acids (FFAs) and volatile organic compounds (VOCs) were analyzed by GC–MS, followed by multivariate analysis, relative odor activity value (rOAV) analysis, and correlation analysis. Muscle samples from the three breeds showed comparable pH, lightness, and shear force values, whereas BDT exhibited higher redness and yellowness values. Breed-related differences were mainly observed in specific flavor-related compounds. Glutamic acid was higher in CLH (27.77 μg/g) and BDT (27.11 μg/g) than in AH (21.21 μg/g; p < 0.05). Stearic acid (C18:0) was higher in BDT (63.72 μg/g) than in CLH (41.10 μg/g) and AH (36.37 μg/g; p < 0.01). Docosatetraenoic acid (C22:4n-6) was higher in AH (9.33 μg/g) than in CLH (7.31 μg/g) and BDT (7.29 μg/g; p < 0.01). A total of 201 VOCs were annotated in raw-muscle headspace. Although overall VOC profiles were broadly similar among breeds, differences were observed in specific VOCs and annotated odor attributes, and rOAV analysis identified multiple compounds as potential aroma contributors. Correlation analysis followed by false discovery rate (FDR) correction showed that only Ile and Lys were significantly negatively correlated with o-xylene, whereas the associations of Tyr, C20:3n-6, and C22:4n-6 with VOCs were exploratory and did not remain significant. These co-variation patterns may reflect shared upstream metabolic or oxidative pathways rather than direct precursor–product conversion. These findings characterize breed-related differences in the flavor-associated chemical profiles of raw lamb muscle; however, their implications for cooked-meat aroma and perceived flavor require further validation through descriptive sensory analysis and cooked-meat VOC measurements.