Choice of harvest date can modulate the aroma intensity of herbaceous/vegetal, fresh fruit and cooked fruit nuances, thus helping the winemaker to produce wine of different styles and balance. Relationships between the sensory attributes and aroma compounds of Merlot and Cabernet-Sauvignon grapes that were harvested sequentially and the resulting wines were evaluated for two vintages: 2012 and 2014.
The fine-tuning of the harvest date modulated the aromas of the young wine and impacted the intensity of the cooked fruit aromas for both Merlot and Cabernet-Sauvignon. No correlation was observed between the must and wine in terms of the intensity of the cooked fruit aroma. In order to observe an impact on the intensity of the cooked fruit aroma it was necessary to delay the harvest date of Cabernet-Sauvignon by 4 to 12 days in 2012 and 2014 respectively. This value was 7 days for Merlot wines (2014 vintage). Furanones, lactone and ketones were well correlated with the perceived intensity of the cooked fruit aroma in the young wine. In addition, the highest concentrations of γ-nonalactone, 3-methyl-2,4-nonanedione, massoia lactone and furaneol were detected in Merlot wines made using late-harvested grapes. At the measured concentrations, these compounds can explain the aroma of cooked fruit detected in the red wines. Similar results were obtained for the Cabernet-Sauvignon wines made from grapes from a later harvest.
The volatile compounds produced from the lipoxygenase pathway in the grapes were putatively involved in the evolution of the aroma of the red wines from sequential harvest dates, opening up the possibility of managing aroma profiles through harvest date decisions
The findings of the present study show how the late harvest of Merlot and Cabernet-Sauvignon berries can induce a significant modification of the aroma of the wine without, surprisingly, clear modifications to the aroma of the must. This study therefore demonstrates that it is difficult to accurately predict wine aroma through the sensory evaluation of must aroma. In addition, our study shows that a short delay in harvest can induce a significant modification to the sugar concentrations of the must and increase the intensity of the cooked/dried fruit aromas. The molecular basis for these modifications is the increase in the impact of aroma compounds in must and wine, such as furaneol, MND, (Z)-1,5-octadien-3-one, massoia lactone and γ-nonalactone.
Future research is needed to determine if the observations regarding sensory and aroma compound evolution are applicable to varieties growing under different climatic conditions. Finally, these findings may help the wine-producing sector develop tools for preventing cooked/dried fruits aromas in wines, which will be increasingly challenging in the context of climate change.
To find out more: read the article published in Oeno One magazine and watch the videos “Climate change and red wine aromas: focus on cooked fruit notes“
