Release and perception of γ-nonalactone and massoia lactone in the red wine matrix: impact of ethanol and acidity

Abstract

Climate change (CC) is altering grape/wine composition, challenging wine sensory quality. Rising temperatures increase grape sugar levels, with higher wine ethanol (EtOH) contents, reduce total acidity (TA) converging with increased pH and lead to the accumulation of CC odorous markers such as γ-nonalactone (γ-C9) and massoia lactone (ML). These alterations often require acidification to preserve microbial and chemical stability, and taste balance of wines. The objective of this study is to investigate for the first time the sensory impact of matrix-aromas interactions in wines representative of the main CC compositional effects in their whole.

Model wine matrices (9) were reconstituted from deodorized red wine, using a full factorial design based on 3 ethanol levels (12, 14, 16%), 3 pH/TA ratios (3.2/8=0.4, 3.6/6.5=0.55, 4/5=0.8) and spiked with γ-C9 (155 ppb) and ML (26.8 ppb). The combinations simulated progressive CC impact from proper (12%, pH/TA=0.4, no CC effects), to alarm (14%, pH/TA=0.4, CC influencing EtOH levels with TA corrected by acidification) till dangerous (14%, pH/TA=0.8, CC affecting TA without correction; 16%, pH/TA=0.8, extreme CC effects) scenarios of wine quality.

Discriminating (triangle test: TT) and descriptive (RATA) sensory tests and SPME/GC-MS quantitative analyses, were carried out to test the impact of compositional changes applied to the matrix on the perception and release of γ-C9 and ML and to explore perceptual interactions.

TT showed significant differences in γ-C9 and ML perception in wine with 16% of EtOH and corrected by acidification (pH/TA=0.4), indicating in this condition a combined effect of EtOH and acidic profile on their perception likely driven by physical-chemical phenomena. GC-MS analysis of wine headspace confirmed the highest release of γ-C9 and ML in this condition. Moreover, RATA results showed that in extreme CC conditions (16% EtOH, pH/TA=0.8), the addition of γ-C9 and ML led to a shift in aroma profile: red fruit notes, characteristic of the whole wine, were no longer perceived, while sweet notes became dominant, suggesting a significant matrix effect on the olfactory impact of these compounds.

These findings highlight that CC and corrective actions can significantly impact wine sensory quality. Our study points out that adjusting the acidic profile of wine may favor γ-C9 and ML perception linked to CC and premature aroma aging. These results suggest that in a complex matrix like red wine, adjusting a single parameter may be not enough, and a holistic approach should be adopted.

References

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Piombino, P., Di Fede, R.S., Pittari, E., Moio, L., (2024). Understanding trends of wine sensory quality in the current context if climate change. In book of abstract of 45th World Congress of Vine and Wine, Dijon, France.