Mechanistic basis and process modulation of wood-aged beer aroma: A critical framework for predictive design

Wood aging in beer has re-emerged as a strategy to generate complex sensory profiles that couple fermentation-derived aromas with wood extractives and, in the case of reused cooperage, previously adsorbed volatiles. Compared with wine and spirits, however, wood-aged beer remains more difficult to interpret mechanistically because outcomes are shaped by interacting effects of wood-related inputs, beer matrix constraints, microbial activity, and process conditions, while inconsistent terminology continues to hinder cross-study comparison. This review reorganizes current knowledge of wood-aged beer aroma formation and modulation within a mechanistic framework, aiming to support more interpretable experimental design and transferable process guidance across research and practice. We first summarize directly extractable wood-derived odorants, emphasizing how wood species, processing regime, format, dosage, and usage history shape the extractable pool. We then examine how the beer matrix influences extraction, redistribution, and aroma delivery. Finally, we discuss microbe-mediated transformations of relevant precursors and their process-level implications for microbial selection and inoculation strategies. Collectively, current evidence suggests that wood aging in beer is best understood as a coupled wood-beer-microbe-process system rather than a simple extractive event. Within this multivariate system, future progress will require marker-based interpretation of dominant formation processes, clearer distinction between primary aroma levers and conditioning background variables, and stronger sensory-causal validation of candidate markers. Integrating sensomics with flavoromics may further connect chemical signatures to sensory relevance and marker-condition relationships, while authenticity- oriented fingerprinting can provide an additional verification layer for predictive aroma design in wood-aged beer.