Changes in Quality Characteristics, Microbial Communities, and Metabolomic Profiles of Mianning Ham During Different Aging Periods

Mianning ham is a traditional dry-cured ham from southwestern China, but the coordinated relationships among quality changes, microbial succession, and nonvolatile metabolite remodeling during long-term ripening remain poorly understood. Therefore, samples of Mianning ham aged for one, two, three, and four years were comparatively analyzed. High-throughput sequencing was used to characterize microbial community composition, and untargeted metabolomics was applied to analyze differential metabolite changes and their associations with dominant microorganisms. The results showed that the physicochemical and sensory characteristics of Mianning ham exhibited stage-dependent changes during ripening, with moisture content and pH generally decreasing, while color, texture, and mature flavor characteristics gradually developed. Multivariate statistical analysis identified 99 differential metabolites, which were mainly involved in peptide accumulation, amino acid metabolism, and nitrogen-containing compound transformation. The bacterial communities were mainly composed of Bacillota and Pseudomonadota, while Ascomycota was the predominant fungal phylum. Distinct successional patterns of dominant microbial taxa were observed at different ripening stages. Furthermore, microorganism–metabolite correlation analysis revealed distinct association patterns between internal and surface samples of the ham. Internal microbial communities were mainly associated with nucleotide-related metabolism- and umami-related characteristics, whereas surface microbial communities were more closely associated with the transformation of protein-derived nitrogen-containing compounds and the accumulation of flavor precursors. This study provides insights into the quality formation patterns of Mianning ham during ripening and offers a theoretical basis for ripening-stage evaluation and quality regulation.