It's All In The Tannin – Wine 101

Lizzie, our web guru, has asked me to reply to a question about why wine improves with age. Someone asked the question on a forum, and the Wikipedia answer in response was “When properly stored, wines not only maintain their quality but many actually improve in aroma, flavour, and complexity as they mature.” Not very helpful.

And of course it isn’t true of all wines – in fact it isn’t true of most wines. It’s easier to understand if we restrict ourselves initially to red wines.

Let’s Look At Red Wine

Glass of wine being pouredWines do change over time, but mostly that just means they go off. Most obviously, their colour degrades. If you take a wine from last year, and compare it with a 2004, for example, you’ll see the new wine is very purple.

Although on their own they’ll both look a lovely, deep red (assuming they’re any good), comparing one with the other, you should easily be able to decide that one is ‘purple‘, the other ‘ruby‘.

This colour degradation will continue over time until the wine becomes almost brown, and eventually begins to break down and appear as sediment in solution.


The way to slow down this degradation is to have high tannin levels in the wine to start with – the tannins give structure to the wine, and allow it to be stored for a long period of time.

This doesn’t mean that adding a lot of tannin to any wine means it can be kept for decades. The balancing act is that if a wine is to be stored over a long period, it must have high tannin levels. With high tannin levels from the pips and skins, the wine can be stored longer in oak, and even in new oak, without overpowering the wine. Length of time in oak, and the use of new oak, both add to tannin content of a wine.

Cabernet Sauvignon

Cabernet Sauvignon Grapes on a VineThe classic red wine grape with high tannin content is cabernet sauvignon. This is the traditional grape used to add ‘structure’ to a wine. That’s why clarets can be stored for so long.

Wine makers in Chianti found that improving techniques were producing wines worth keeping longer. So they introduced small amounts of cabernet sauvignon to give the wine the necessary structure to hold it all together while the wine aged and mellowed.

But Not All Wines Improve With Age

So, not all wines improve with age. As I’ve explained, if a wine does improve with age, it needs high levels of tannin to provide the structure that prevents the wine from degrading.

Then it’s a question of luck – does all that tannin from the grapes and the barrels produce a taste that is pleasing on the palate? High levels of tannin in a young wine taste very bitter – you can gauge the level of tannin by swilling the wine around the front of your teeth. If they feel rough and dry, that’s tannin, a foolproof test.

Wine Warning

These wines need to be left for the maturing process to work its miracle. That’s why some wines come with a warning – not to be drunk for 5, 10 or even 15 years. Almost always this means the winemaker has decided that the best this wine can ever get is if it is matured for x years with y amount of tannins from leaving the wine on the skins, and z amount of tannins from storing in oak for a certain amount of time, with a certain percentage of new oak.

Changing any of these variables will change the time when the wine is at its optimum, but the pleasantness of the wine at the new optimum will be less, in the view of the winemaker.

And the longer the winemaker has decided is the optimum time, the more undrinkable the wine will be as a young wine. For example, a really high quality Pauillac like Mouton Rothschild will be primarily cabernet sauvignon, kept for a while on the skins and stored primarily in new oak. After 12 years it will be mellow and beautiful. After 3 years it would be very bitter indeed.

It’s About Balance Too

But you can’t take a Vin de Pays de l’Herault, or an ordinary Pinotage from California, leave the skins in, use lots of new oak and store it for 20 years. Yuk! Very, very acidic, with no balancing fruit. It’s about balance. Is the wine fruity enough to take a heavy dose of tannin sufficient to store it for long enough to allow the fruit and the acid to evolve to equilibrium? That’s a wine you can age – and it sounds very much like a good quality claret to me!

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