Metagenomics-based insights into the microbial community composition and quality characteristics development...

The objective of this study was to elucidate the formation mechanisms of quality characteristics in traditional dry-cured ham. The microbial community composition in three types of dry-cured ham was analyzed using metagenomics technology. Volatile flavor profiles were characterized via gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS), while peptide profiles were determined using liquid chromatography-mass spectrometry (LC-MS). Based on metagenomic data, biosynthetic pathways of volatile flavor compounds and bioactive peptides in dry-cured hams were reconstructed. Key microorganisms identified include Staphylococcus equorum, Staphylococcus saprophyticus, Aspergillus glaucus, Aspergillus ruber, Debaryomyces hansenii, and Debaryomyces fabryi. Using GC-MS and GC-IMS, 25 volatile compounds were identified in dry-cured ham, with branched-chain compounds exhibiting higher odor activity values (OAVs). LC-MS analysis identified 203 microbial-derived peptide fragments, predominantly possessing angiotensin-converting enzyme (ACE) inhibitory, dipeptidyl peptidase-IV (DPP-IV) inhibitory, and antioxidant activities. Further investigation into the contribution of microbial communities to the characteristic quality attributes revealed that Staphylococcus species promote the formation of 3-methyl-butanal via branched-chain amino acid transaminase (BCAT) and 3-hydroxy-2-butanone via acetolactate synthase (ALS). With regard to functional bioactive peptides, Staphylococcus indirectly contributes to the synthesis of NPPKFD, DLEE, and KRQKYD via glutamyl endopeptidase activity. Additionally, proteins derived from Aspergillus glaucus (actin-related protein 5) and Staphylococcus equorum (chromosome segregation protein) serve as direct precursors for bioactive peptides, yielding potential sequences such as KNSKDPVSI and LEDDI. This study provides evidence indicating the role of microbial communities in shaping the quality characteristics of dry-cured ham.