Contribution of Piperitone to the mint nuances perceived in the aging bouquet of red Bordeaux wines

Abstract

During the tasting of a fine, old wine, the aromas generated in the glass are intertwined in an intimate, complex manner, expressing the fragrance of the aging bouquet. This aging bouquet, which develops during bottle storage through a complex transformation process, may result in a broad palette of nuances. Among these, undergrowth, truffle, toasted, spicy, licorice, fresh red- and black-berry fruit and mint descriptors were recently identified as features of its olfactory representation for red Bordeaux wines. Although a targeted chemical approach focusing on volatile sulfur compounds revealed the role played by dimethyl sulfide, 2-furanmethanethiol, and 3-sulfanylhexanol as molecular markers of the typicality of the wine aging bouquet of red Bordeaux wines, its chemical transcription has only partially been elucidated. As the aromatic signature of wine aging bouquet results in a complex mixture of odorants, reconstitution experiments represent a powerful strategy to provide confirmation of odorant identification and understand how sensory interactions between these aromatic compounds modify the overall perception of wine aroma. In that context, a multiple step approach, combining sensory evaluations of red Bordeaux wines and aromatic reconstitutions of wines extract fractions, was used to identify other molecular markers involved. One wine expressing both a high aging-bouquet score and a high mint nuance received particular attention. Various reconstitution and omission tests highlighted the contribution of two specific fractions to the perceived intensity of mint aroma. Then, gas-chromatography coupled to olfactometry and mass spectrometry was applied to those two targeted fractions to identify chemical compound(s) responsible for the mint nuance. A similar analytical process was applied to homologous fractions of minty essential oils to help in characterization and interpretation of the mass spectrometry data. This approach resulted in the detection of piperitone , a monoterpene ketone with an odor reminiscent of mint. The sensory importance of piperitone was also underlined, as its addition at levels found in wines produced an increase in the perceived intensity of the minty character, both in aromatic reconstitution and in wine. Interestingly, piperitone was found at significantly higher concentrations in wines with an aging bouquet, which highlighted for the first time its contribution to the positive mint aroma of fine aged red Bordeaux wines.