When thinking of wines in terms of maturation, images of tranquil, dusty cellars are conjured up, lined with bottles of wines that have been resting in the dark for years – or even decades. But what does it mean to age or mature a wine? What actually happens to the precious liquid over time? And why are some wines made to age, while others are more for immediate enjoyment? Let’s investigate.
First off, a common misconception is that only red wines are suitable for ageing. This is not true, and white wines can age as gracefully and sublimely as their red counterparts. When white wines age, the colour will change gradually from a vibrant hue – often yellow with a greenish tinge – to a richer, more straw-like colour. With extended time in the bottle, the wine can even start browning in the bottle. Younger white wines have more astringency and acidity, but over time this integrates into the wine, leading to a smoother mouthfeel. Primary fruits and fresher aromas give away to tertiary characters, which are usually towards oaky, biscuity notes that come to the fore. White wines that have been oaked (e.g. Chardonnay) as well as wines with high acidity and low pH (e.g. German Riesling) are also very suitable for maturing
Young red wines display more purple hues (very visible if you look at the rim of the wine, in the glass). As the wine ages, this purple hue fades and a brick-red colour develops over time. The ageing process also influences the tannins. In young wines, tannin molecules are small enough to interact directly with your tastebuds – so when you sip a young red wine, the tannins taste more pronounced. As the wine ages, these small tannin molecules start clumping together (a process called polymerization). Once this starts to happen, the molecules cannot interact with your tastebuds. The polymerization of tannins smooths out the wine, bringing a lovely silkiness to it.
Eventually, these polymerized tannin molecules can drop out of the wine, forming sediment. The sediment does not affect the wine negatively and can be dealt with by carefully decanting the bottle. As with the white wines, there is a shift from primary aromas (fresh fruit characteristics) to tertiary ones (tobacco, cigarbox and leather).
Ageing is essentially an oxidation process, so how a wine ages will be influenced by the type of closure it is under. Glass stoppers (a curiosity, but used throughout the world) can in many ways trap the wine in time, allowing almost no perceptible maturation. Screwcap closures with tight seals will slow down the ageing of the wine. DIAM corks are more permeable, which will allow more evolution than screwcaps, and natural cork will allow the most pronounced maturation of a wine.
But how can you tell which wines will age well, and which will not? Price is not always a sure-fire indicator, but typically more expensive wines will likely age better, due to more judicious use of oak and extraction (i.e. more tannins). Producers with a known track record of wines that age beautifully is also a good indicator that a younger vintage will share the same pedigree. Certain cultivars are also more suitable for ageing, such as Cabernet Sauvignon, compared to a wine typically made in a lighter style – such as Cinsault or Grenache Noir. Other factors that can determine the ageing potential of a wine include the acidity: wines with a higher acidity, like Nebbiolo and Pinot Noir, can be predisposed to a better maturation potential. Sugar is another factor that plays a role – acting as a preservative, ‘sticky’ wines (including straw wines and noble late harvest wines) often age incredibly well.
How you store wines when you age them is key to ensuring the best result. The best way to store wines is on their side, and away from direct light. Temperature is key – you are aiming for between 10°C and 13°C. Above 15°C, the wine matures at a faster rate, and heat can even push the cork out and allow even more oxygen into the bottle. Don’t store them at too low temperatures, though; under 10°C, the evolution of the wine slows down to the point where the chemical processes that drive maturation come to a halt.
Lastly, looking at the maturation of larger format bottles – in theory, the larger bottle should age at a slower rate than the standard 750ml. The ratio of air (headspace) to volume is smaller in magnums, double magnums etc. This effect can be compromised if the larger format bottle is filled and closed by hand, as this could let in more oxygen, which will accelerate the ageing process.