Friday, June 24, 2011

Tannin Story

The Gazette-Montreal

Wine: The skinny on fat tannins



Cabernet sauvignon grapes growing in Australia’s Coonawarra region. Many winemakers would pick them at this stage, but by leaving them on the vine longer, the tannins become softer.

Photograph by: Bill Zacharkiw, Special to The Gazette

MONTREAL - I received an email asking what I mean when I write about “fat” tannins with respect to red wines. It’s been a while since I have delved into the more technical side of winemaking, so here’s “the skinny” on tannins.
What exactly is a tannin?
Tannins are the cause of that drying sensation in your mouth when you drink a red wine. They are a group of chemical compounds that can be found in diverse sources like fruits, tea and wood. They find their way into a wine via the stems, skin and seeds of the grape, and from the wood of barrels. They are a constant preoccupation during the grape-growing and winemaking process, because how they are dealt with has a profound effect on the style of the wine that makes it into the bottle.
To understand the different qualities of tannins, you need to know why they are there in the first place. For the grapevine, tannins act as a defence.
When young, grapes are green and taste extremely acidic and bitter because the seeds of the fruit are the vine’s way of reproducing, but the plant only wants its fruit to be eaten when the seeds are ripe. The green colour of the grape skin not only camouflages the bunches among the leaves, but more importantly, if an animal does find them and decides to have a little snack, the unripe and aggressive tannins in the skins and seeds will give the grape a horribly bitter taste that drives off the nibblers.
As grapes ripen, the skin colour changes, making it stand out and more attractive. At the same time, it becomes less acidic and sweeter to the taste, and most important, the tannins become less bitter. This is called “phenolic” ripeness.
One of the problems in the past, especially in cooler European climates, was that grapes were not picked when fully ripe, and the wines had what we call “green tannins.” These are quite harsh, and very drying in the mouth, like a tea that has been steeped for a few hours.
Winemakers strive for ripe tannins. Along with acidity, tannins are the most important structural element of red wine. White wines are made differently; with the juice spending next to no time in contact with the skins, so tannins don’t play an important role in its structure. In reds, they serve as a preservative and give it potential for aging.
They also provide the wine with structure and backbone, like a picture frame, focusing the fruit and other flavours.
The two types of ripe
So if it is simply a case of making sure the grape skins and seeds are ripe, what’s the problem? Well, as I have mentioned in previous columns, ripeness is a very relative thing. The tannins and seeds are only part of what a winemaker looks at when grapes are growing.
The other thing that happens as the grape ripens – which, in wine lingo, is referred to as veraison – is that as the sugar levels increase, the acidity decreases, which is also known as sugar ripeness. (Think of how tart an unripe apple is compared with one that is ripe.)
The problem is that these two “ripenings” don’t always happen at the same time. In hotter regions or during very hot vintages, the grapes ripen so fast that sugar ripeness is often achieved well before phenolic ripeness. (This happened in much of Europe in the heat wave of 2003.)
This phenomenon puts grape growers in a bit of a bind. Because the tannins aren’t quite ripe, the grapes have to be left on the vine longer. By the time the skins and seeds have finally caught up, there is very little acidity left in the grapes and sugar levels have skyrocketed.
So while there are many factors explaining why alcohol levels have crept up so much during the past decade, one of the reasons is because winemakers are waiting for phenolic ripeness.
One person’s sweet is another’s fat
Another thing has happened to grape growing and tannin management that is also tied in with this idea of relative ripeness. If you are a fan of cabernet sauvignon, or compared a wine from California with one from Bordeaux, you might have noticed that the Californian wine will be much less mouth-drying.
Much of the movement in modern winemaking has been to make wines as easy to drink as possible from the get-go. And one of the things winemakers focus on is tannin ripeness.
While “what is ripe” has changed with respect to grape flavours – many winemakers hate anything resembling a green or herbaceous note in their wines – the same can be said for tannins.
When I taste with New World winemakers, they often refer to the quality of the tannins in their wines as “sweet” because they have taken tannin ripeness to an extreme – at least in my view.
While green tannins are extremely hard and bitter, classically ripened tannins are still a bit drying. These wines, like traditionally made Bordeaux and Chianti, can be a bit dry if you drink them on their own in their youth. These are the type of tannins that I often refer to as “gritty,” “firm” or “tight.”
Wines that have traditionally been made for cellaring have these types of tannins. As the wines age, these tannins become less drying. How this process happens is still not fully understood, but essentially the tannin compounds bind together to form chains. The end result is that they dry out the mouth much less.
But many people don’t want to wait for tannins to soften in bottle. In more modern wines, especially those from California and Australia, they want “sweet.” This sensation comes from higher alcohol levels, riper fruit flavours, new oak barrels and, yes, from riper tannins.
By leaving grapes longer on the vines, the tannin compounds start to modify themselves directly on the vine. Again, how they do so is still not fully understood, but when the grapes are turned into wine, they do not dry out the mouth and why they are referred to as sweet.
While I agree that they do not give a bitter taste, I find they don’t “hold the wine together” nearly as well, making the wine feel too rich. This is why I often refer to them as fat, though I will also use words like “soft,” “round” or “plump.”
Is one style better than another? Much of it depends on your palate preference. I don’t put sugar in my espresso because I like bitter, and my palate was formed during the 1990s by European wines, which tended to have a lot of bitterness. Many of you have started with sweeter, New World wines.
Is there a perfect tannin level out there? No. Much like everything in wine, it is about personal preference.

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