Postmortem aging promotes umami formation, yet its mechanisms differ markedly among chicken edible tissues. We compared glutamate (Glu), inosine monophosphate (IMP), enzyme activities, and umami intensity in eight tissues during chilled aging. Skeletal muscles showed clear Glu accumulation and moderate IMP degradation, whereas internal organs exhibited minimal changes in both metabolites. Cartilage displayed little metabolic response due to limited substrate levels. Δ analyses revealed distinct tissue-dependent patterns of Glu increase and IMP behavior. Spearmanʼs rank correlation showed only weak, non-significant associations between Glu change and aminopeptidase activity (ρ = － 0.54) and between IMP change and 5′-nucleotidase activity (ρ = － 0.40), indicating that enzyme-metabolite relationships varied substantially across tissues. These findings demonstrate that umami formation during postmortem aging is driven by divergent tissue-specific responses, reflecting enzyme-dependent amino acid release in muscles, minimal IMP turnover in organs, and substrate-limited metabolism in cartilage.