Impact of filtration processes on the key chemical components of Shanxi aged vinegar

Shanxi aged vinegar, a traditional Chinese solid-state fermented vinegar, is widely recognized for its unique flavor and high quality, attributed to its complex chemical composition. Filtration is essential for improving vinegar clarity and stability, yet its impact on bioactive and flavor-related compounds remains unclear. In this study, high-performance liquid chromatography and gas chromatography-mass spectrometry were used to analyze compositional changes in Zilin Shanxi aged vinegar before and after filtration. Results showed that filtration, through membrane retention and interfacial adsorption, selectively modulated organic acids, amino acids, flavonoids, volatile compounds, and taste-active peptides, thereby altering the sensory profile. Post-filtration, total acidity, amino acid nitrogen, and salt-free solids slightly decreased but remained within national standards. In contrast, reducing sugars and total esters increased significantly, improving the sugar-acid balance and enhancing taste smoothness. The total content of volatile pyrazines increased, although some individual compounds decreased. High-molecular-weight flavonoids were partially removed, while low-molecular-weight monomers increased. Peptide profiles also shifted, particularly for umami-related peptides. These findings provide a scientific basis for optimizing filtration protocols in traditional vinegar processing and support the development of standardized strategies that preserve functional compounds while improving sensory quality.