Flavour signatures of Duolang lamb from arid-desert and temperate regions: precursor chemistry, aroma validation and metabolomic links.

This study investigated flavour precursor chemistry, lipid oxidation status and aroma-active compounds in Duolang lamb produced in two contrasting ecological regions of Xinjiang: the temperate continental region of northern Xinjiang (BDL) and the arid-desert region of southern Xinjiang (NDL). Fatty acid, free amino acid, nucleotide and metabolomic profiles, together with TBARS values, were determined in raw longissimus dorsi muscle, whereas electronic-tongue responses were measured in cooking broth and volatile and aroma-active compounds were analysed in meat after standardised boiling. BDL meat contained higher total fatty acids (1976.03 vs. 879.10 mg/100 g), saturated fatty acids and monounsaturated fatty acids, whereas NDL meat showed a more unsaturated lipid profile, with higher polyunsaturated fatty acids (152.76 vs. 96.56 mg/100 g), particularly C20:3n-6 and C20:4n-6. NDL also had a higher mean TBARS value than BDL, although the difference was not significant. NDL raw meat contained higher sweet amino acids, IMP, GMP, AMP and equivalent umami concentration, while its cooking broth showed higher instrumental responses associated with sweetness, umami and richness. Aldehydes dominated the volatile fraction in both groups. Aroma validation confirmed hexanal, 1-octen-3-ol and (E,E)-2,4-decadienal as common contributors to cooked lamb aroma, while (Z)-6-nonenal, 3,5-octadien-2-one and (E,E)-2,4-nonadienal were more relevant to the NDL aroma profile, and (E)-2-nonenal to BDL. Metabolomic profiling linked these differences to glycerophospholipid, linoleic acid, arachidonic acid, histidine and beta-alanine metabolism. Overall, the two regional-origin groups differed in raw-meat flavour precursors and cooked aroma profiles under their respective production environments.