Purity is often pretty high up on the list of desirable attributes when it comes to fine wine. But this intent is sometimes at odds with the process of winemaking. A process which involves plenty of influence beyond just the grapes. Even in low intervention wines (those that eschew additives, commercial yeasts etc), oak, concrete tanks, stainless steel, glass and cork – are all typically used. Wine is a hugely volatile liquid and much of this equipment’s influence is necessary in order to protect it from spoilage and oxidation.
But each material brings its own texture and flavour. For vignerons obsessed with terroir expression, and therefore wines without affectation, how can winemakers reduce the impact of their tools, while preserving wine’s purity?
The use of stainless steel tanks in winemaking was first introduced in the early 1960s and marked a new chapter in bringing greater fruit purity to wine. Bordeaux legend Émile Peynaud was a key advocate of their adoption. Stainless steel was soon endorsed throughout the winemaking world, bringing a new level of clarity and precision to wine. Its lack of porosity meant that the fruit flavour was less compromised. The introduction of temperature-controlled tanks could also keep fermentations cool, avoiding the loss of the grapes’ aromatics and preserving the vibrancy of the fruit. It is also very effective in protecting the wine against oxidation. But, despite stainless steel’s seeming neutrality, many winemakers have turned their back on it, favouring concrete and oak vessels, and now even tanks made from glass instead.
The issue with stainless steel is particularly noticeable in places like the Southern Rhône, where the Mistral wind plays havoc with wines in steel tanks. Quite how an annual wind that blows through the valley can have such an effect, might seem a mystery to many, but winemakers have realised that this wind causes strong variations in air pressure – resulting in huge amounts of static electricity being stored in vessels that conduct it. A steel tank is much more conductive than a concrete one or the inert oak barrel. It turns out the huge build-up of static electricity can considerably alter the texture of a wine, particularly when it comes to a red wine, rich in tannins.
For Xavier Vignon – one of the Southern Rhône’s most celebrated winemakers, consultants and all-round alchemists – this became even clearer under the dark cloud of Covid. Vignon caught Coronavirus early on in the outbreak, and like many, he lost his ability to smell and taste for a number of months. Professionally, this is potentially disastrous for a wine consultant whose artform is blending. But losing his smell and taste, at least for a time, allowed him to concentrate on other factors when it came to the blend. When I spoke to Vignon, he made a point that fortunately he was sick between March and May – a time when, commercially, he wasn’t required to blend. This however, allowed him to experiment with things beyond flavour. “Without taste you start to concentrate on texture,” he says, “the composition, the balance. This started to dictate my blending and my winemaking.”
Vignon believes the static electricity in stainless steel tanks has a number of negative effects on the texture of the wine. “It destroys the roundness of the wine, it destroys the sweetness. The softer tannins are reduced, whilst the harder tannins stay in the wine.” Static electricity is everywhere. Vignon tells me how a petrol tanker travelling down a motorway can generate so much static electricity that, if not earthed, touching it would be fatal. For wine, Vignon says, “The electricity from the top to the bottom of the tank can be as much as 50 volts; 9,000 hectolitres can produce 600 volts of static electricity!”
While the return to concrete tanks and large old wooden casks is preferable for most in the Southern Rhône, Vignon still believes this is a compromise. “Even in concrete tanks there is iron in the composite, which creates static electricity in the blend,” he explains. The clay amphora – a trendy maturation alternative – also brings its own distinct chalk-like texture, so for him is not a solution.
Inert oak is a successful counter to the problems of static electricity, but it is not a neutral vessel. While oak has an affinity to certain grape varieties – many perceive its ability to accentuate certain fruit and spice characteristics – if on a quest for purity, the use of oak will always be a trade-off.
It is not only oak’s flavour, but its porosity that has the biggest effect on compromising a wine’s purity, particularly with smaller barriques. “The difficulty for small volumes of wine is that it is exposed to lots of oxygen – since the tank is smaller and it is easily affected by atmospheric temperatures as well as humidity, this causes lots of evaporation,” says Vignon. “To protect the barrel from oxidation you therefore need to keep topping up the barrel. Every time you top up, you are adding oxygen to the wine. Therefore, you have to keep adding more SO2 also.” This, Vignon feels, masks purity.
This led him to experiment with ageing wines in the ocean – an experiment that worked to great effect. Wines aged in barrels in the sea saw no change in temperature, no variation in pressure, and no static electricity build-up. This meant there was no evaporation. Therefore, there was no need to top up the barrels and removed the need to continually add more SO2. His experiments resulted in Vignon’s “vinarium technique”, where he suspends barrels of wine in larger tanks of wine – enabling him to age the wines for long periods of time without having to expose them to oxygen. While this might solve oak’s issues of oxidation, limiting SO2 inputs and avoiding the textural alterations caused by static – it still doesn’t avoid the compromise of oak’s flavour impact.
There is one material in winemaking, however, that eliminates this and is starting to make inroads across the fine wine regions of the world: glass. Many top winemakers in Bordeaux, Burgundy and beyond are already experimenting with it – although many are not yet willing to go on record just yet. It is not that they are unhappy with the results, but they feel it is too early to be completely sure. These include the very finest châteaux and domaines around the world.
Glass, unlike stainless steel is inert so there are no issues with static electricity. Glass, unlike oak, is non-porous and therefore does not impart any flavour to the wine. With these qualities combined, could it become the material of choice for the vignerons desperate to produce wines of absolute purity?
WineGlobe is a French company that has started to produce giant spherical glass containers of different sizes to ferment and mature wine. Designed by Michael Paetzold, an oenologist by training, a scientist and a vigneron – he claims they are the first glass vats in winemaking history. After three years of trialling the vessels, the result amongst winemakers around the world has been impressive. David Suire, celebrated Bordeaux wine consultant and winemaker at Ch. Laroque, believes that the making and maturing of wines in glass globes produce wines that “are surprisingly whole, with their flesh... mouthfeel and a radiance of unique purity.”
For Vignon, glass is the logical solution from his own experimentation – so much so, he is in the process of building a winery made completely of glass. Grapes, and the resultant wine will have no contact with any porous or static material in his quest for purity. It has seen him embrace this material with great excitement and it is revolutionising his approach to winemaking. His next hurdle, is how to avoid the cork.
The cork is another porous material that can potentially influence the flavour of the wine. While cork taint has been greatly reduced, it is the cork’s porosity – even as a composite – that is the issue. It is one step away from producing a wine completely unaffected by its materials. Vignon does not have a solution yet, but is experimenting with melting the glass at the top of the bottle neck – therefore avoiding the need for a closure at all. How this works practically and commercially is still yet to be seen.
While it remains too early to say, glass has the potential to become a much more prominent material in winemaking. At the moment, it remains an expensive option – therefore limited to fine wine for now, and even then, there are few, if any, cuvées made entirely by glass. But if the technology allows for it and it continues to find favour in the winemaker’s experiments, it could go some way to solving vignerons’ quest for purity.
