As a world-leading expert on white wine vinification, professor and director of general oenology at the university in Bordeaux, and manager of four family properties in Bordeaux, Denis Dubourdieu is called upon for winemaking advice by leading producers all over the world. STEPHEN BROOK meets wine’s most famous scientist.
As a world-leading expert on white wine vinification, professor and director of general oenology at the university in Bordeaux, and manager of four family properties in Bordeaux, Denis Dubourdieu is called upon for winemaking advice by leading producers all over the world. Stephen Brook meets wine’s most famous scientist.
Denis Dubourdieu is a familiar figure around Bordeaux. In addition to his research lab, he runs his family’s wine estates, and advises many other properties. Dubourdieu is a slight figure, often glimpsed with his spectacles pushed onto the bridge of his nose, and with his eyebrows slightly raised in a look of perpetual amused scepticism.
He is renowned for his research into white wine vinification. He explained and advocated the process of skin contact for white grapes before pressing; and elucidated the function of lees-stirring (bâtonnage) during the barrel-ageing of white wines.
As owner, or co-owner, of a number of properties, the success of his methods is put to the test with every vintage. His wife Florence inherited Château Reynon in Béguey, where he has made the wine since 1977; in 1982 they jointly founded Clos Floridène in the Graves, and in 2000 he took over the management of his father Pierre’s celebrated Barsac property, Doisy-Daëne.
Strange, then, that Denis Dubourdieu has made his name studying wine styles that many would consider marginal within Bordeaux. ‘I was born into white wine,’ he explains. ‘My father and grandfather made nothing else. My university thesis was on sweet wines, and I researched the aromas of white wines and the action of fine lees.’
The oenology faculty at Bordeaux University, unlike that at UC Davis in California, is known for the close relations between its academics and the local wine industry. Many Bordeaux professors are also consultants, following a tradition that began with the late Emile Peynaud, who was a winemaker before becoming an academic.
Despite his research background, though, Denis Dubourdieu is now increasingly in demand as a red-wine consultant. ‘What has always interested me, and those for whom I work, is how to produce wines with a certain finesse.’ Today he has clients such as Haut Bailly and Cheval Blanc.
The science of winemaking
As a scientist, Dubourdieu has always been open to technical innovation. So what does he make of micro-oxygenation, by which small, controlled doses of oxygen are injected into wine, during fermentation or barrel-ageing? The idea is to soften harsh tannins, minimise the need for racking, and render the wine more accessible when young. First developed in Madiran to tame the bruising tannins of the indigenous Tannat grape, it has since become very fashionable in regions such as St-Emilion.
‘Every winemaker knows that oxygen is vital to production,’ he replied. ‘The only question is when it needs to be added and how much. In my view, the risk of too much oxygen is greater than the risk of too little. The crucial factor is the ability of any wine to resist oxygen. Overdo a technique such as micro-oxygenation, and all wines will taste much the same, whereas my goal is to bring out the personality of each wine.
‘Micro-oxygenation can certainly make a wine taste better when young, but no one knows its long-term consequences. It isn’t necessarily sensible to make up a girl of 12 as though she were 18.’
Denis Dubourdieu is not against innovation, however. ‘One of the pleasures of being a winemaker is that there’s always room for experimentation,’ he says. ‘The last thing anyone wants of an airline pilot flying a 747, for example, is innovation, but a winemaker can enjoy trying out different techniques.’ Such as genetic modification (whether of yeasts or vines), maybe?
‘Any development of GM vines is a long way off,’ he says. ‘And there is absolutely no need for GM yeasts. Great wine is about complexity, and the role of GM products will be to simplify. So for that reason alone, it’s of no interest – stupid even. I doubt the development of GM yeasts or vines is a real threat, as there is such public opposition. Those in favour argue that a GM vine eliminates the need to rely, for instance, on fungicides. But what they don’t say is that a GM plant has a built-in fungicide!’
Biodynamism is another technique that is spreading fast through many leading estates of Alsace and Burgundy, but is almost unknown in Bordeaux. Why so?
‘The wines produced by this method are often excellent – and sometimes terrible,’ says Dubourdieu. ‘It has not caught on in Bordeaux because by instinct we are sceptics, descendants of the Enlightenment, and not ready for a new war of religion. Anyway, the best estates already follow many of the doctrines of biodynamism – but omit the magic potions.’
He is reluctant to discuss future projects. ‘I’m more confident talking about what has been discovered already. In the past decade we have demonstrated that what creates aromas is the metabolism of yeasts, which takes non-aromatic molecules and liberates odours characteristic of the variety. That means that certain yeasts are better adapted than others to extracting aromas. The yeasts found in Sancerre, for example, are better adapted to cold climates, and by chance also extract more aroma. So we can now explain in scientific terms the typicity of Sauvignon Blanc.
‘We have done research into the aromas produced by wood-ageing, and explained the role of malolactic fermentation in barrel in producing those aromas. We have identified the constituents responsible for the premature oxidation of white wines. The usual suspects are water stress and poorly managed vinification. And we are working on the same problem with red wines that develop pruney, figgy aromas – identifying the molecules responsible for this transformation, which often occurs if the grapes are picked when over-ripe.
Given his vast experience of Bordeaux winemaking, does Dubourdieu feel changes in the vineyard or winery are affecting the typicity of Bordeaux, for good or ill?
‘Certainly vinification methods have changed over the past 15 years. But change is a positive thing. Any winemaker works within the context of his times, of his own tastes, of the techniques at his disposal, and the tastes of consumers. The wines produced in the 1950s, for example, were made in very different ways to those of recent decades, but they are still recognisably Bordeaux.
‘The major changes have been in the vineyard. Practices once considered exceptional – low yields, higher density, leaf-pulling, green-harvesting – are now the norm at well-run estates. The other big change is the growing proportion of Merlot in vineyards. That too is not necessarily to be deplored. In the 1970s a great deal of Cabernet was planted on deeper soils, where it only ripened in exceptional vintages. Far better to plant Merlot on such soils and keep Cabernet for the well-drained, gravel soils where it is unsurpassed.
‘The only thing that might endanger the typicity of our wines is the path of excess: overripe Merlot, over-extraction, over-oaking. Such wines resemble each other too closely, and can tire the palate. But happily I think such wines are falling from fashion.’
And will the typicity of Bordeaux change in the future? ‘Who knows? Perhaps climatic warming will persuade growers to plant more Petit Verdot, which can give excellent results in hot years. But overall I believe Bordeaux will remain Bordeaux, in that most wines will show fine fruit, fresh tannins, moderate alcohol levels.’
Finally, I asked how Bordeaux would cope with growing competition from the New World and even the south of France. ‘For modest Bordeaux produced by more or less industrial methods, the competition could indeed be a threat. On the other hand I believe there is a fine future for white and red Bordeaux produced from good terroirs at a sensible price. They offer a diversity of pleasure rarely matched by the more standardised varietal wines of other countries.’