The quest for growing the finest Chardonnay wines
Discover the latest research from the University of Bordeaux and its Institute of Vine and Wine sciences (ISVV). An interview with Axel Marchal, associate professor at the ISVV, following the publication of the article “Toward a Molecular Understanding of the Typicality of Chardonnay Wines: Identification of Powerful Aromatic Compounds Reminiscent of Hazelnut” in the Journal of Agricultural and Food Chemistry.
Chardonnay is one of the most renowned and popular white grape variety in the world. It originated in the Burgundy wine region of eastern France, but is now grown wherever wine is produced, from England to New Zealand. The aroma of the famous wine created from this variety is most commonly compared to tropical/green fruits (such as pineapple and melon). Notes of butter/caramel, honey may often be remarked as well as woody and citrus nuances. However, the aroma of the finest Chardonnay wines (cultivated in Burgundy, the most highly reputed chardonnay wine growing 'terroir') is different. According to Dr. Marchal, “here the chardonnay presents a complex bouquet which evokes jasmine, verbena, bergamot and hazelnut”. This comparison for Burgundy Chardonnay wines with hazelnut-like aromas can be traced all the way back to 19th century records– a period when such naturalist descriptors were not yet even commonly used!
Despite this perception of a hazelnut descriptor in Chardonnay wines, up until recently, no specific investigation to provide a chemical explanation, had been carried out into the source of the aroma. This all changed when Denis Dubourdieu* (renowned professor in oenology, highly reputed oenologist, passionate wine-maker, academic, producer and consultant all in one) decided to further explore the matter, launching an official research project in 2013. Accompanying him in his research was another specialist, Dr. Valérie Lavigne, as well as Prof. Darriet and his laboratory at the ISVV.
Making fine wines
Not a simple process, making fine wines. A winemaker faces three main challenges:
- Satisfy the customer.
- Differentiate his/her wine from the rest.
- Reveal the true identity of the wine.
A maximum amount of knowledge is necessary to reveal the true taste of the wine, a taste that reflects its origins, its ‘terroir’ and that is inimitable. The mission of research is to bring this information to the wine-making process.
The answer is close collaboration between the wine cellar and the laboratory.
Axel Marchal —
Looking for the source of the hazelnut aroma
In this particular research project, for the first time ever, researchers were trying to detect the aromatic compounds/molecules that give the Burgundy chardonnay a particular hazelnut aroma. They were looking for the answers to the questions:
- Which molecules, within the entire “orchestra” of molecules are responsible for the hazelnut aroma of the wine?
- How do these key aromatic compounds/molecules form?
Analytical chemistry devices are used to identify the molecules within the wine. The process used in this research project, gas chromatography, separates the molecules and permitted the identification of four compounds reminiscent of hazelnut, pyrroles. However these molecules did not provide enough aroma to account for the nuance of hazelnut in wine in terms of their concentration. Nevertheless, work continued and the hypothesis of mixed second key components, thiopyrroles (thiol derivatives), was explored, with success! So not one, but two highly odoriferous grilled hazelnut-like compounds were discovered in Chardonnay wines. A very positive result that provides “new insights into the molecular origin of the volatiles contributing to the identity of typical Chardonnay wines to improve their winemaking and aging techniques.”**
But the research never ends and several questions remain. For example, how do the thiopyrrole molecules actually form? Do other “star” molecules carry the aroma of hazelnut? And what about other key aromatic compounds that are responsible for the very particular aroma of the Burgundy chardonnay. What gives the wine its jasmine, verbena, bergamot aroma? The research thus continues at the ISVV of the University of Bordeaux and promises further revelations. Ultimately, the aim of such research is to reveal and best express the terroir. Axel Marchal concludes, “thanks to the discovery of these aromatic compounds, the wine-making process of the burgundy chardonnay wine may further improve, thus revealing the true personality of the chardonnay and expressing as best as possible its ‘terroir’”.
> Consult another article on wine – this time on wine-tasting as explained by Dr. Marchal.
The Institute of Vine and Wine sciences of the University of Bordeaux is a multidisciplinary pole of research, higher education and development dedicated to facing the future challenges of the wine industry. The current director of the ISVV is Prof. Alain Blanchard who succeeded Prof. Dubourdieu in 2016.
The overall mission of the Institute, as described by Denis Dubourdieu, is to “understand to act” within the processs of vinification. This consists of understanding the different factors and elements that make up a great wine, including the molecules. “If we understand the origin of the aroma, we can better manage the wine-making process and thus achieve the ultimate goal: a wine that best expresses its terroir.” (Axel Marchal)
* Pr Denis Dubourdieu passed away on July 26th, 2016.
** Article “Toward a Molecular Understanding of the Typicality of Chardonnay Wines: Identification of Powerful Aromatic Compounds Reminiscent of Hazelnut”, Journal of Agricultural and Food Chemistry.