Abstract
Barrel maturation of specialty beers involves migration of aroma compounds between beer, wood, oxygen, and resident microbial communities, producing complex changes in flavour stability and sensory depth. This study examines aroma compound migration during barrel maturation of specialty beers. Beer samples were aged in wooden barrels under controlled cellar conditions and analyzed across defined maturation intervals. Wood-derived volatiles, esters, phenolic compounds, organic acids, aldehydes, dissolved oxygen, colour, turbidity, and sensory descriptors were measured. The results show that early maturation increased wood-derived aroma compounds, including vanilla, spicy, and toasted notes. Continued ageing promoted oxygen-mediated transformation, ester integration, and phenolic softening. Excessive barrel contact increased astringency and woody dominance, reducing beer balance. Microbial activity contributed additional acidic and complex aroma layers in selected samples. The study demonstrates that barrel maturation quality depends on controlling contact time, oxygen ingress, wood extraction, and microbial contribution to achieve balanced specialty beer aroma.