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The Science Of Wine Aging

The Science Of Wine Aging

The aging process is one of the most important factors when it comes to wine: find out how physics and chemistry affect it

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The glass is there, before us. We pick it up carefully, so as not to warm it. Following a ritual of tiny gestures, we take in its colour, odour, and then, finally, we taste it. Of course, we’re talking about wine: but what makes a wine more or less valuable? The explanations could fill an entire encyclopaedia, but today we’re going to examine one of the most important factors when it comes to wine: the aging process.

Wine that’s just been recently produced is a mixture of substances that often don’t blend well amongst themselves. Just the passage of time causes a reaction that generates new aromas, which are what then characterizes a precise wine. There are various substances responsible for this process, but the ones we’ll concentrate on are the esters and tannins. Esters are created when the alcohol from the wine reacts with its own acids, and are what gives the wine its perfume. Esterification is a very unstable process, and is influenced by the wine’s acidity, which in turn is determined by the quantity of hydrogen present in the liquid. This is why the aromas and perfumes can be so varied according to the age of the wine: a slight variation of acidity can transform a fruity aroma to a buttery one.

Tannins, especially in red wines, are even more important. These are polyphenols, astringent substances, which is why a young wine – rich in polyphenols – tends to leave an unpleasant “dryness” in the mouth. On our palate, tannins tie to the proteins that lubricate our saliva, making it less slippery. But once a wine begins to age, the tannins begin to transform. They alter the colour of the wine, making it darker, and lose their astringency – thereby giving the wine a more delicate flavour. The transformation of tannins is at the base of a proper aging process, despite the fact that scientists have only recently been able to explain what happens to these elements during this process. After only a few weeks of aging, a wine’s tannins undergo a reaction called “glycosylation”, a process that ties the tannins to the sugars present in the wine.

This is why it’s often thought that the more a wine ages, the better it will be: tannins eventually are entirely transformed, as are the esters and the other compounds. The truth is, wine is subject to a range of instable reactions, where there’s a constant flux between “before” and “after”, and vice-versa. An ester, for example, can be re-transformed into its original reactants. This means that, while the passing of time can help improve a wine, it also increases the risk of exposing it to factors that may compromise its quality.

Which is why it’s so important to be aware of certain specifics. First of all, we should avoid subjecting wines to temperature fluctuations, maintaining it between 12°-15°C. Humidity should be between 70%-80%, which will ensure that the cork doesn’t dry out and let in unwanted air. This is why bottles should be kept tilted at an angle, with the cork always in contact with the wine. And of course, direct light should also be avoided – it’s ideal to keep wine in the dark – as should any kind of vibration, so that the bottom residue of the wine (which should never be filtered) gets deposited, and not mixed together with the liquid. Following these simple suggestions will ensure that our wine is conserved in the best possible manner, and the aging process takes place properly. But for how long? This varies according to the type of wine and the vintage, but in general, 5-7 years is sufficient for the majority of wines. After which point, it’s time to open a bottle and raise a glass.

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