Time-dependent accumulation of biogenic amines and microbial succession during dry-aging of beef: safety implications

Dry-aging of beef under controlled temperature, humidity and airflow reshapes the surface microbiota and may influence biogenic amine (BA) accumulation. In this study, culture-based enumeration, 16 S rRNA gene profiling of combined crust + inner meat, and validated HPLC quantification of BAs were integrated to track safety- and quality-relevant changes over 60 days. Sequencing showed Pseudomonadota and Bacillota consistently >95 % of reads; communities were dominated by Pseudomonas, Brochothrix and Psychrobacter, with Acinetobacter rising at mid-aging. Alpha diversity peaked at day 35 (Shannon 1.33 → 2.12; overall P = 0.0225; day 35 vs day 1, adjusted P = 0.0069) and became heterogeneous by day 60. Culture confirmed a surface-led, aerobic succession: crust counts increased and Pseudomonas reached 5.6 log CFU/g at day 60, whereas inner-muscle counts declined across groups; pathogens were not detected. In the inner meat, cadaverine rose from non-detectable to 31 ± 37 mg/kg at day 60 P < 0.001), spermine peaked at day 35 (52 ± 14 mg/kg; P < 0.001), while histamine remained <5 mg/kg and other BAs showed no significant change. All inner-meat BAs remained below commonly cited concern ranges, though late-stage variance indicates sporadic hot spots, likely reflecting diffusion from the crust and proteolysis-enabled precursor supply. Integrating microbes and metabolites identified two ecological–metabolic tendencies linking psychrotrophic genera with polyamines or diamines. In practice, day 35 emerges as a quality “sweet spot,” whereas approaching day 60 warrants tighter surface management and targeted monitoring of pseudomonads, Enterobacteriaceae and cadaverine/putrescine.