Exudate-based biomarkers as minimally invasive tools for monitoring meat freshness under refrigerated storage

This study evaluated whether package exudate can serve as a minimally invasive matrix for freshness monitoring in vacuum-packed beef and pork stored at 2 ± 0.5 °C for 21 days. Physicochemical and microbiological indicators, including pH, color, lipid oxidation, protein carbonyls, total aerobic count, and Escherichia coli, confirmed progressive spoilage during storage (p < 0.05). Exudate pH and microbial loads closely reflected deterioration patterns observed in meat tissue. HS-SPME-GC-MS analysis revealed substantial storage-dependent changes in volatile organic compounds (VOCs) in both tissue and exudate. Exudate VOCs responded earlier than tissue VOCs, with 51.6% of beef-exudate VOCs and 43.8% of pork-exudate VOCs significantly altered by Day 7 relative to Day 1 (p < 0.05). Multivariate analyses identified 12 candidate biomarkers in beef exudate and 14 in pork exudate. These findings demonstrate that package exudate provides sensitive and early spoilage-related signals and represents a promising substrate for freshness-monitoring applications.