Impact of climate‐induced compositional shifts of ethanol and acidity on aroma release and perception in red wine: a case study on γ‐nonalactone and massoia lactone

BACKGROUND Climate change-driven warming is increasing wine ethanol, promoting an atypical convergence between pH and titratable acidity (TA), and favouring the accumulation of specific wine volatiles: γ-nonalactone (γ-C9) and massoia lactone (MLac). This study evaluated how ethanol and acidity modulate release and sensory impact of γ-C9 and MLac in red wine. A deodourised commercial red wine was reconstituted into nine model matrices using a 3 × 3 factorial design (12%/14%/16% v/v ethanol; pH/TA ratios 0.40/0.55/0.80) and spiked with γ-C9 and MLac. Headspace release was quantified by solid-phase micro-extraction-gas chromatography–mass spectrometry (HS-SPME-GC–MS), and trained assessors performed triangle tests and rate-all-that-apply (RATA) profiling (orthonasal, retronasal, taste/mouthfeel). RESULTS Orthonasal perception results showed that γ-C9 was discriminated in all low pH/TA matrices, and also MLac was perceivable in high ethanol/low pH/TA matrices. These sensory results were explained by a higher release of the lactones in the headspace of wines with 16% v/v and low pH/TA; however, some sensory differences were not explained by headspace changes, suggesting matrix-dependent perceptual interactions. RATA indicated a shift from citrus/tropical notes towards sweeter/ethereal nuances with greater body as ethanol increased and/or pH/TA rose, while taste ratings showed reduced sourness and increased bitterness at high ethanol/high pH/TA. CONCLUSIONS Overall, these results suggest that ethanol and acidity act as interactive modulators, influencing volatile organic compounds (VOCs) release, their perceptual integration, and taste balance. In this context, enological practices such as wine acidification, essential to counteract climate-induced imbalances, should be carefully evaluated for their potential ability to enhance the sensory impact of γ-C9 and MLac and overall sensory quality in red wines.