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Unearthing The Secrets Of Wine Ageing

What actually makes wine age? And why do some evolve better than others? Rupert Joy explores the multi-layered mysteries of maturation.

Wine spends most of its life in a bottle. But what actually happens during the wine ageing process is a bit of a mystery.

Laying down wine is not an exact science. Drink a wine too early and you get fresh primary fruit flavours – delicious, but unknit and hardly what you paid all that money for. Drink it too late and the fruit has gone, leaving a dried-out husk. In between, wines go through curious ‘dumb’ periods, when they seem to withdraw into themselves and brood.

But get it right and the rewards are huge: the ethereal fragrance and multi-layered complexity of a great wine at its peak are well worth the wait. So finding expert guidance is important. The trouble is that, despite the wealth of wine expertise that exists, no one fully understands the process of wine ageing.

The theory of wine ageing is straightforward. It is the interaction of oxygen with polyphenols (tannins, colour pigments and flavour compounds), acids and alcohol in a wine that produces change. Potential longevity depends on the quality and concentration of these components. As renowned Bordeaux oenologist Pascal Chatonnet puts it: ‘The ability to limit oxidation is the key factor in wine’s aptitude for ageing. In reds, the polyphenols play the main role; in whites, it’s the acids.’


Wine Ageing -Nature or nurture?

The phenolic elements in red wine come from the grapes – anthocyanins (colour pigments) from the skins, and tannins (structure) from the skins, pips and stalks. Red wines with very low tannin levels tend to degrade fast because they are less stable. Those with a high concentration of polyphenols and a deep colour usually have a longer future. So the quality of the grapes, and what happens in the vineyard, matters.

For Sylvain Piteot, respected estate manager at Clos de Tart in Morey St Denis, ‘The main determinant of a vin de garde is the quality of tannins – and that depends on the ability of a terroir to produce ripe tannins. You can’t make a great vin de garde with unripe tannins.’ Chatonnet agrees: ‘Terroir is key: vinification and barrel maturation are about making the most of a great terroir or compensating for a lesser one.’


Yields are also critical during the wine ageing process. Vines and grapes compete for nutrition: a vine cannot endow 10 bunches of grapes with the same level of phenolic richness as it can five. With higher yields, the ratio of polyphenols to juice is reduced. Vine age is a factor, too: young vines produce bigger grapes with more juice and thinner skins, and their roots are shallower so they suck up more water. The grapes they produce tend therefore to be less rich in phenolic components.

However fashionable it may be to play down the role of the winemaker, a range of decisions taken in the winery also impact significantly on a wine’s longevity. First among these is the length and temperature of maceration, during which polyphenols are extracted from the grapes: a vin de garde may require a longer and hotter maceration to extract the tannins.

The amount of sulphur dioxide added to the wine makes a difference: SO2 has an antioxidant and antiseptic effect, limiting oxidation and eliminating the bacteria that make wines unstable. And filtration can reduce longevity, because it reduces the solids in the wine. Selected yeasts can also play a role, if winemakers choose to use yeasts that help to fix colour.

Oak ageing, and particularly the amount of new oak used, is another determinant for longevity. Oak barrels add tannin, increasing a wine’s resistance to oxidation. The permeability of barrels enables oxygen to interact with the wine, encouraging the tannins and anthocyanins to combine. This combination process helps to stabilise a wine’s colour and structure.

So far, so relatively simple. But, needless to say, there are exceptions that challenge these assertions: some of Bordeaux’s great long-lived wines of the past were made from much higher yields than today, using relatively little new oak, and they were heavily filtered.

And then there is Burgundy. The concentration of polyphenols in such grape varieties as Cabernet Sauvignon and Syrah helps explain why the great wines of Bordeaux and the Rhône are long-lived. But how do you explain the ability of Burgundies – made from Pinot Noir, a grape low in polyphenols and prone to oxidation – to age? As Chatonnet says, these are ‘hardly monsters of phenolic concentration’.

The Burgundy question

Aubert de Villaine of Domaine de la Romanée-Conti finds the wine ageing process a mystery. He cites the domaine’s Romanée-Conti Grand Cru 1975 as an example. ‘1975 was a very poor year: the wine was very thin, low in tannins and colour. Thirty years later, this wine is sublime, with all the delicate aromas typical of this grand cru.

‘The longevity of Romanée-Conti is hard to explain. It is always paler than our other grands crus such as Richebourg and Grands Echezeaux, and lower in anthocyanins, tannins and acidity. Yet despite coming from the same vegetal material and being vinified in the same way, it ages better and has more finesse than the others. I can’t explain why this is so. Some wines just seem to have a talent for ageing.’

Over in the Rhône, Jean-Louis Chave, whose iconic red and white Hermitages are highly sought after, thinks there is an

‘X-factor’ to longevity: ‘Of course the interaction of tannins, acidity and alcohol helps determine a wine’s ageing. But the key role is played by an additional factor, one with no scientific name – minerality. The mistake producers make today is to tire out young wines by using techniques such as micro-oxygenation for reds and bâtonnage for whites, which makes them gain in weight but lose minerality’.

Significantly, while most red wines age primarily on their tannins, some seem to age on their acidity. A Burgundy with a very high pH (low acidity) would be unstable, but a Bandol with the same pH would not, because Bandol has much higher tannin levels and tannins have an antiseptic effect. ‘But high acidity is not necessary in itself,’ insists Piteot. ‘Some great years like 1947 had low acidity and have evolved well.’

Long-lived whites

If you’re confused by what makes red wines age, try whites. With white wines, the wine ageing process seems to have little or no correlation between phenolic content and longevity. White wines have much lower phenolic concentration than reds, yet grape varieties like Riesling, which are very low in polyphenols, can age superbly for decades.

The world’s longest-lived white wines, such as top Sauternes, German Beerenauslesen and Tokaji, tend to be high in acidity and sugar, and are often also affected by botrytis. It is thought that acidity in particular, but also sugar and botrytis, play important roles in stabilising white wine. Another key factor is barrel fermentation and maturation, where a wine’s prolonged contact with the lees (dead fragments of yeasts) seems to help stabilise it.

As Chatonnet points out, ‘Acidity is not in itself a guarantee of harmonious ageing. Muscadet [which is high in acidity] ages a lot less well than ripe, or even over-ripe, Chardonnay. But acidity does directly influence other factors such as bacterial stability, the anti-oxidising role played by SO2 and the speed with which polyphenols oxidise.’

Given all the uncertainty, why bother to age wines? Is longevity really so important? Aubert de Villaine thinks so: ‘A great wine is by definition a wine that will age well.’ Jancis Robinson MW agrees. ‘Really great wine is great because of its complexity of tertiary flavours, which can only be achieved over a long period in bottle. I would say that Condrieu is perhaps the most obvious example of a potentially fine wine that is not particularly suitable for bottled wine ageing. But I can’t think of any other fine wine that shows its charms so early.’

Of course, not all long-lived wines are necessarily as harmonious as their shorter-lived counterparts. It is all about balance. There has been much speculation about the future of the 2003 vintage, which tended to be relatively low in acidity. But Piteot has ‘no doubt that the 2003 Burgundies will be long lived – and keep longer than the more classic 2002s and 2004s – because the tannins were very ripe. But they will never have the balance and freshness of the 2002s.’

Chave says many people who lay down wine don’t really know what to expect. ‘It is a paradox of our time that people look for rich, concentrated, powerful wines that will age – without understanding that wines lose their fruit and power as they age. They think that the architecture will last, whereas all that is left with age is the patina.’ He continues, ‘Old wines are extremely good value nowadays because the recent, publicised vintages are the most sought after. In the past, a great wine’s reputation came with time. Today, a wine becomes “great” in the interval between the harvest and the en primeur tasting the following spring.’

New style: Wine Ageing 

Some have suggested that modern, ‘softer’ wines age less well than those made in the past. Chatonnet says this is a myth. ‘The suggestion is absurd. Aged wines were appreciated historically because wines were often undrinkable young due to unripe grapes, high acidity, random malolactic fermentation and very astringent tannins.

‘If you go back a bit further in history, to the end of the 18th century, a year’s young wine was actually sold at a much higher price than older wine because it was hard to guarantee that it would keep well, let alone age, due to microbial transformations.’

What about those legendary century-old bottles that critics rhapsodise about? The cellars of Bouchard Père & Fils in Beaune hold an amazing collection of old wine, dating back as far as 1846. Christophe Bouchard himself is an enthusiast for old wines and wishes more consumers had the patience to wait. But he agrees that 19th century wines were not inherently any more ageworthy than those made today.

Ultimately, identifying the zenith of a wine’s evolution is almost impossible – and a matter of personal taste. Robinson puts it neatly in her book Vintage Timecharts: ‘In a sense, one never knows for sure when a wine has reached its peak until that peak is past and the wine begins to show signs of decline.’ One thing’s for sure though – once a wine is past its peak, there’s no turning back.

Rupert Joy is a diplomat and occasional wine writer

Jancis Robinson On When To Open Those Most Prized Bottles

What are the key things that you look for when estimating a wine’s potential longevity?

‘With red wines, you need a certain charge of tannin but also a real core of flavour and extract, and a good balance of – or at least sufficient – acidity and alcohol. With white wines my judgments are probably more experiential, but intensity of flavour is one factor, and there seems to be some correlation between high acid levels and ageing potential.’

Do dense, rich New World wines tend to age less well?

‘I suppose the famous Ridge Monte Bello 1971 and the Stag’s Leap 1973 that showed so well recently [in the 2006 re-run of the 1976 Paris tasting] could have been described as ‘dense, rich wines ‘ when they were made, yet they have lasted superbly, whereas the Freemark Abbey Bosche

1969 didn’t. It’s a question of balance, I think, rather than New World v Old World, as the latter’s Bordeaux of the 1970s had not aged as gracefully at that tasting.

I am concerned that many high alcohol/low acid wines will not age particularly well, but it’s probably too early to tell. This is a relatively recent phenomenon.’

What are the most remarkable long-lived wines you have tasted?

‘I have tasted wines from several very ancient bottles at Hardy Rodenstock tastings, of which the most memorable was an 1811 Yquem. A dry Steinberger Riesling made at Kloster Eberbach in 1897 was a marvel earlier this year, as were an 1865 Montrachet and an 1865 Clos Vougeot from Bouchard Père et Fils’ cellars.’

The Best Bets For Wine Ageing

For the reds, the classic Old World keepers are the safest bets: classed-growth Bordeaux; great Burgundies; the best Rhônes from Hermitage, Côte Rôtie and Châteauneuf-du-Pape; top Sangiovese-based wines from Tuscany (Chianti, Brunello and so on); great Barolo and Barbaresco from Piedmont; the best Tempranillos from Spain’s Ribero del Duero and Rioja; and, longest-lived of all, port. For Old World whites, great German Rieslings, the best Burgundies and white Rhônes, dry and sweet Chenin Blancs from the Loire, top Alsaces, Sauternes, Tokaji and vintage Champagne.

The New World is more of a lottery – not because its wines age inherently less well, but because they are less homogenous. The New World has established classics with proven ageing ability, such as Australia’s Penfolds Grange and California’s Ridge Monte Bello Cabernet. A few regional styles like Coonawarra Cabernet or Hunter Valley Semillon have developed a reputation for longevity; and producers such as Australia’s Penfolds, Wynns and d’Arenberg consistently make wines that age well. South Africa’s Kanonkop even suggests a drinking curve on the back label of its excellent Paul Sauer blend. But for the most part, it is a question of personal experience (and an element of risk-taking).

Some of the wine world’s lesser-known treasures can develop beautifully in bottle. These include Château Musar from Lebanon, Mas de Daumas Gassac from Languedoc and Portuguese reds from the Bairrada, Dão and Colares regions.

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