A sensory study of the ageing bouquet of red Bordeaux wines: A three-step approach for exploring a complex olfactory concept

• Wine professionals conceptualized wine ageing bouquet into eight semantic classes.
• A core of seven aromatic descriptors structured its sensory definition.
• Three of them were found significant for wine discrimination.
• Free association task and citation-frequency help to define this complex concept.

The ageing bouquet, which defines the overall quality of fine wines, counts among the most fascinating but least known phenomena in oenology. Its complexity and subtlety are highly-valued attributes, together with the perfume and flavour of a fine wine.The aim of this work was firstly to explore whether wine professionals shared a common representation of the ageing bouquet of red Bordeaux wines and then to move on how they perceive and translate its main sensory characteristics. In a first step, a large panel of wine professionals including winemakers, wine-science researchers, oenologists, wine consultants, and graduate students in oenology were invited to answer a questionnaire about their personal definition of the wine ageing bouquet concept. The lexical field generated through a free association task revealed that conceptualisation of the ageing bouquet involves a wide variety of quality dimensions, where intrinsic attributes, such as sensory clues, complexity, balance, and positive ageing evolution, play an important role. Importantly, this step showed the occurrence of a confusion of the ageing bouquet with a reductive fault of wine among the panel and emphasised the need for a careful selection of assessors before moving on to the next wine tasting steps.In a second step, 30 red Bordeaux wines were assessed by 13 wine professionals from the Bordeaux area who were selected among the best skilled ones thanks to the initial step of our study. They were initially required to score to which extend each tasted wine represented a qualitative ageing bouquet. Then, they were invited to freely express their individual sensory descriptions for those with the highest scores. A profile of aromatic attributes of the ageing bouquet typicality of these wines was then compiled on the basis of the frequency citation method. Although all wine professionals were not consensual in their assessment of the typicality of individual wines during tasting, they were able to express a collective representation of the main odour characteristics of a wine’s ageing bouquet. Their olfactory representations tended to highlight a pool of seven main aromatic notes: undergrowth, truffle, toasted, spicy, liquorice, mint, and fresh red- and black-berry fruits. As a third step, a validation of these seven more frequently elicited aromatic descriptors was addressed through a profiling of their sensory intensity by the panel. Three out seven (undergrowth, truffle, and spicy notes) were turned out significant for wines discrimination among the assessors. Overall, this study provides new insights into the ageing bouquet concept in red Bordeaux wines and offers an interesting framework for carrying out subsequent conventional quantitative sensory analysis as well as initiating qualitative and quantitative chemical work.