Comparative analysis of fatty acids, amino acids, and flavor compounds in different skeletal muscles of the Tianzhu white yak.

Abstract

Objective: Although yak meat is valued for its distinctive flavor profile, little is known about the mechanisms underlying flavor variation among different muscle types. This study aimed to systematically investigate the differences in flavor precursors, metabolic enzyme activities, gene expression profiles, and volatile flavor compounds among three muscles-longissimus thoracis (LT), triceps brachii (TB), and semimembranosus (SM) of the Tianzhu white yak, and to elucidate the underlying regulatory mechanisms.

Methods: A comprehensive approach was employed, integrating targeted metabolomics, untargeted metabolomics, flavoromics, real-time quantitative polymerase chain reaction, and histochemical staining to compare the biochemical characteristics of the three muscles.

Results: The results of volatile profiles and sensory evaluation demonstrated that the TB muscle exhibited more favorable flavor-related traits. The TB muscle was enriched in key flavor precursors, including glutamic acid, glutamine, arginine, and total free amino acid content (p<0.05). Concurrently, the expression levels of key lipogenic genes (FASN, ELOVL4, SREBP1) were significantly higher in the TB muscle (p<0.05). Flavoromics analysis further revealed that the TB muscle exhibited greater diversity and higher relative abundance of key volatile compounds, such as aldehydes, ketones, and alcohols (p<0.05). Sensory evaluation further indicated that the TB muscle exhibited stronger sweet and fruity flavors. Untargeted metabolomics and pathway enrichment analysis indicated that this profile was associated with enrichment of arginine and proline metabolism and unsaturated fatty acid biosynthesis.

Conclusion: This study demonstrates that flavor enhancement in yak meat is associated with the coordinated upregulation of lipid synthesis genes, thereby promoting the accumulation of flavor precursors. This process provides sufficient substrates for the Maillard reaction and lipid oxidation, facilitating the generation of volatile flavor compounds. These findings provide a theoretical basis for yak meat quality evaluation and precision processing.