Acidity

We often talk about a wine being high in acidity. Frequently, that's a good thing, but what is it? How do we know simply by tasting whether a wine is high in acidity or low in acidity or somewhere in between? What are these acids? Are they safe?

Let's start out by figuring out what we mean. We could be talking about total acidity which some might refer to as titratable acidity. Or we could be talking about the strength of the acidity which is measured in pH (a scale of 0 to 14 where the stronger the acid, the lower the pH and water having a pH of 7).

Which one is it that we are concerned with? Really, it's not quite either one. 

What we are looking for is the freshness, the tartness or sourness of the wine. Is it crisp? Ot is it fatty, for example? Wines with high acidity can balance out the rough tannins that give us the sweetness and the bitterness in a wine.

To understand, let's consider the lifecycle of a grape. One of the celebrated moments in wine country is veraison. This is that point in time when the color of the grapes changes significantly. They go from youth to adulthood. They go from growing to ripening or maturing. Immediately before veraison, the acidity of a grape is at its highest and the sugar content or sweetness is at its lowest. If you want to test it, find a winery that you can get to easily and a proprietor or winemaker willing to play along. Visit early in the season and taste a grape or two. Go back several times during the season as it gets closer to harvest and taste the grapes again.

Where do these acids come from? In the grapes, they occur naturally just as they do in other foods. Try an asparagus or a brussels sprout. These are vegetables that kids tend to not like, but adults are much more likely to have an affinity for them. COuld it be that our confort with acidity increases as we go from that point in life when we are griwing to that point when we are maturing? As we mature, do we go from sour to sweet (lots of parents of teenagers surely want to know)?

In young grapes, and frankly even in more mature grapes but at lesser levels, we find three primary acids -- tartaric, malic, and citric -- in grapes with the levels of acidity varying significantly by grape species. 

Acids are used during the winemaking process as well. We've learned a number of times about malolactic fermentation, the process by which overly tart tasting malic acid is converted to softer, smoother, sweeter, lactic acid. Other acids may be added to maximize the preservation effects of sulfites or to stabilize the color of the wine. In red wines, for example, when you see a wine with a significant blue tinge to it (Carmenere, Syrah, etc), the wine is typically low in acidity.

So, when you are tasting a wine, how do you know how acidic a wine is and do you care?

If you get a pins and needles feeling on the sides of your tongue, that is the acidity acting in your mouth. Of course, if there is too much of it, the wine tastes offensive. On the other hand, if there is none, the wine tastes flat and flabby and frankly fails to define the flavors in the wine. 

There is a delicate balance here. A hallmark of a great winemaker who produces great wines is getting the level of acidity right in her or his wines.