Sunday, July 4, 2010

What Makes Wine Turn Into Vinegar?

From the You Asked Department

UPDATE: This article has been updated. Click here to find out what makes wine turn into vinegar.

I'm no expert, but I do feel silly when someone asks me a question about wine that I can't answer; especially when the question seems plain and simple. I was standing in line at the airport in Naples a few days ago, on my way home for the first time in 1 year and 4 months, and I met a fellow traveler. He'd spent some time in Bordeaux recently and loved the wines. We talked a bit and then he asked, "hey, are you like a wine writer or something?" Yeah, I responded, I've been studying the wine-making process in Italy for the last 16 months of my life. At this point, I'm feeling pretty good and helpful, then he stuns me: "So, what turns wine into vinegar?"

I do not have a certification in wine. I have never taken a single class on wine. I have tasted a lot, taken notes, and spent hundreds of hours talking with winemakers around the world. Sometimes we're walking in vineyards; sometimes we're in their refreshing cellars; sometimes we're on the roof (x2). Usually, I don't worry too much about my lack of schooling. I believe in self education. My parents were very independent. But sometimes, when technical and scientific questions about wine do arise, I think again.

Is wine about flavors and people or sulfur levels and pH balances? Well, both of course. But, as a wine writer, I prefer to talk about excellent wines at low prices, and to talk to the people who make them. Atmosphere is half of an article on wine, the other half being fact. Scientific analysis is one way that we attempt to understand wine. It is also one way that we try to understand the world, and the world, like wine, is something very beautiful and strange that often cannot be neatly explained. The taste of a glass of wine is beyond words, though we struggle to say something... anything... blackberry, for example, or elegant.

I do enjoy talking about the technical side of wine with winemakers, but not because I find it particularly interesting. It's more like remembering dates in history, or the Big Names: It gives you a series of markers by which to navigate the world of wine. It's my belief that most readers of wine publications are more interested in finding great bottles and being momentarily transported to vineyards all over the globe than they are in learning the amount of sulfur that one winemaker used during one year to kill the bacteria in his wine. Am I right? You tell me. What do you care about?

The scientific approach to wine most interests me when I'm in a curious mood, and The Traveler's question was a damn interesting question: What turns wine to vinegar? Why is this question interesting? I don't know, but it is.

So, anyway...

The Answer

Wine cannot turn into vinegar.

As I mentioned above, winemakers try to kill as much of the natural bacteria that come with the grapes as possible, however, as with all living things, a little bacteria always remains. This bacteria however, is not the kind of bacteria that creates vinegar. One of the most common types of bacteria found in wine is Brettanomyces bruxellensis, commonly known as Bretts. A yeast, Brett's ability to create unwanted smells and flavors is directly linked to unclean winery equipment. It does not make wine vinegar, it merely makes a wine taste bardyardy, or bandaidy. This is one example (debatably) of spoiled wine. Wine can become gross, or spoiled, but it cannot become vinegar.

Unless.... you add the bacteria that turns sugar into acetic acid. This is known as a "mother" among vinegar makers. I recently helped a farmer in the Lazio region of Italy transport a demijohn of 30-year-old vinegar across his barnyard. It had a thick cloud at the bottle of the demijohn, and this is the mother: a unique bacteria that makes vinegar. If you have a mother (and I hope you do), you can turn all of your old wine to homemade vinegar.

Alright, that's enough of wine 101. Any questions?


Anonymous said...

Sorry but I think you are a bit wrong on this. The alcohol in the wine (ethanol) gets oxidised over time by the oxygen in the air to form a carboxylic acid (ethanoic acid also known as acetic acid). Vinegar is just very dilute ethanoic acid.

Mattie John Bamman said...

Thank you for your precision. I've written a more complete answer to this question here:

I think the problem lies in defining vinegar. The short answer is that wine might naturally turn into vinegar if the right conditions are met. However, it might also turn to acetone, and for purposes of cooking, no one wants to cook with that.

Again, thank you for setting the facts straight.