Wine 101: Acidity in wine

Posted by Christopher Gifford on

Acidity in wine

Acidity is one of the four main characteristics on wine, along with tannins, alcohol, and finally, sweetness.

If you're tasting a wine and you get tart or sour taste, that's acidity.

Now, all wines are "acidic" if we're talking the pH scale. Remember that from school? They hover between about 3 to 4.5. The lower the number, the more acidic they are.

The kinds of acid in wine

There are a few kinds of acid in wines, which have a direct effect on how the wine will taste. The main acids in wine are citric, tartaric, and malic.

How to taste acidity in wine

Just like the tea tasting tannin test, in our tannins article, grab a slice of lemon. And feel how your mouth puckers up and salivates when sucking on it. 

If you've tried Riesling, the "dry" style, a Sancerre or a New Zealand Sauvignon Blanc, you'll have a fairly good idea as to where they sit on the acidity scale, compared to, say a buttery oaky Chardonnay.

Now while tannins shouldn't dominate a wine, nor should acidity. What we're looking for, always, is balance. 

This is where sweetness comes in. Sweetness can really balance out and even nullify the acidity.  

A good example is a dessert wine, like a Sauternes. The interesting thing is that it has both a high acidity and quite a lot of sweetness.

Acidity, food & wine matching

When trying to match food with wine, think about the various tastes in the food. There’s sweetness, sourness, saltiness, and fat. 

Your want to choose a wine which will compliment these tastes.

So, here’s one of my favourite pairings. First the wine, a Sauvignon Blanc from the Loire Valley or New Zealand with its bracing acidity. 

Add to that a Goat’s cheese, St. Maure de Touraine, for example.

The Goat’s cheese has a lovely saltiness and fat balance out the acidity of the Sauvignon Blanc. Or, in reverse, the acidity “cuts through” the fatty flavours of the cheese. A match made in food heaven!

Acidity in wine ageing

As I’ve harped on about before, and will continue to do so, the best wines have a harmony and balance between all characters, acidity, tannin, alcohol, and sweetness. 

And while tannins play their role in ageing a good wine, acidity does too, acting as a preservative so that the wine can live for years. Not just for reds, whites too. Particularly a good Riesling or Sémillon.

Climate & acidity

When wine grapes are still on the vine, early in the summer, they have very high acidity. You’ll probably picked an apple off a tree and can recognise the mouth puckering  bitter tartness, realising it should have stayed on the tree.

Back to grapes, as they ripen through the summer and into the early autumn, the acidity starts to dial down, and the sweetness dials up as the sugar levels increase.

They say wine is made in the vineyard before it reaches the winery. The key is to pick the right moment when the grapes have the perfect levels of  sweetness, ripeness, and acidity. And then pick ‘em.

This is where climate comes in.

Ideally, you want a long growing season, to get the grapes to an optimal ripeness where all their phenolic compounds have developed fully. But you also want cooler night temperatures which allows the grapes to maintain their acidity as they ripen. And this doesn't happen everywhere. Northern & southern extremes, cool sea breezes and altitude play their part. 

Pinto Noir, in particular, likes it cool, as do Sauvignon  Blanc and Chenin Blanc.

In fact, the Loire Valley is probably as far north you can go for a long enough growing season for grapes to ripen, and only just about! 

That’s two from four, tannins and acidity. Up next, sweetness and alcohol.

 


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