Analysis of Potential Markers of Pork Freshness Based on Volatile Organic Compounds

Bacteria and endogenous enzymes generate volatile organic compounds (VOCs), which are posited to be the primary source of undesirable flavors in spoilt pork. Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was employed to assess the fluctuations in VOC concentrations in pork stored under tray packaging at 6-8 °C for 10 days, while total volatile basic nitrogen (TVB-N) and total viable counts (TVCs) were used to determine the quality of the pork. During storage, TVCs steadily increased, reflecting the growth of spoilage-related microorganisms, while TVB-N levels surpassed the spoilage threshold early, indicating an acceleration of the degradation process. Nine VOCs associated with pork spoilage were found by partial least squares discriminant analysis (PLS-DA), fold change (FC), and t-tests. The substances comprised ethyl acetate, acetoin, 3-methyl-1-butanol, 3-methylbutanal, 1-octen-3-ol, hexanal, vinyl acetate, 2-methylaziridine, and heptanal. A univariate linear regression analysis revealed a strong positive correlation (p < 0.001) between the gaseous total volatile basic nitrogen (G-TVBN) and the storage duration. Given that G-TVBN accurately reflects changes in pork freshness and the progression of spoilage, these results highlight the potential for dynamically monitoring the freshness and spoilage processes of pork.