My recent post on Madeira got me thinking about acidity, one of the most under-examined aspects of wine — at least from the point of view of the average wine consumer. Admittedly, I am a little bit obsessed with acidity and all things sour. I used to eat lemons as a little kid, there’s a crystal bowl of gummy sours on my desk at work, and just the thought of limeade or a sour cherry pie makes me salivate.

Actually, that’s kind of the point. Acidity makes you salivate, and saliva helps you digest food. That’s one of the many reasons why wine accompanies food so nicely. (It’s also one of the reasons why drinking Italian reds, which often tend to be high in acidity, makes me really, really hungry.) Acidity also imparts a freshness to wine that keeps it lively, and keeps the alcohol and/or sugar from becoming too cloying.

If you’re a fan of Sauvignon Blanc, you know what I’m talking about. That zesty, resfreshing quality makes it nice to sip on its own, and even nicer to drink along with goat cheese, grilled fish or shrimp cocktail (among other things). But acidity also plays a role in red wines, too. Red Loire wines, made primarily from the Cabernet Franc grape, as well as Pinot Noir and Sangiovese (Italy’s most planted red grape and the basis for Chianti) are all known for their ample acidity. These are all grapes that tend toward the more acidic. But the climate the grape is grown in plays a big role, too. So for example, a Pinot Noir from Sonoma’s warm Russian River Valley (I’m partial to Dutton-Goldfield, myself) is generally going to have less acidity than a red Burgundy (also made from Pinot Noir) where the weather is cooler and the sun is more elusive. A lot of wine insiders pride themselves on enjoying wines with elevated acidity. (Full disclosure: I’d put myself in that category.) Part of the appeal is that these wines do go really well with food. And when you’re tasting dozens of wines a day, your palate gravitates towards livelier, lighter wines, rather than syrupy 15% alcohol monsters with little acidity that sit heavily in the mouth.

As with everything, balance is all. Too little acidity and the wine feels dull and heavy. Too much, and you feel like the enamel on your teeth is dissolving. But just the right amount brings everything into focus — think of how a squeeze of  lime brightens up a plate of fish tacos and makes the whole thing work.