Vinegar is a crucial cooking ingredient. Obviously, it’s the cornerstone of vinaigrette and many other salad dressings, but it can also spark up sauces or make a tenderizing marinade. And, as it turns out, it’s easy to make a version vastly better than what you can buy.
When I first started making my own red wine vinegar in 2006, I asked my wife to set up a blind tasting: my first batch versus the hodgepodge of red wine vinegars we had on our pantry shelf.
When she brought out the small bowls, we both started laughing. One of the vinegars had a rich, ruby red color. The others — including some upscale ones — were wan in comparison. The next most colorful vinegar was a pale salmon. So much for the blind tasting.
When it came to flavor, the other vinegars didn’t stand a chance. I never buy wine vinegar anymore. I think about bringing mine when we vacation at some rented apartment, because I know whatever’s there will be thin and coarse.
Vinegar making is basic science. In the presence of oxygen, Acetobacter bacteria feed off of alcohol and convert it to acetic acid. That acid, plus the water from the wine, creates vinegar. Even industrial vinegar makers rely on this basic biology.
Acetobacter is everywhere, even — in small amounts — in wine. In theory, you could leave a half-full bottle of wine on the counter and it would turn into vinegar. In practice, this rarely works for me. Give yourself a leg up by using an existing culture, called a mother, and adding wine to that. Get a mother by asking a vinegar-making friend — we love to share! — or visiting a store that sells it. Oak Barrel Winecraft in Berkeley, California, is my go-to source for vinegar supplies.
Your best bet is to start with red wine, since it generally has fewer sulfites than white wine; sulfites retard vinegar production. Once your batch is going, you can add post-party dregs or do what I do: buy $10 table wines from a decent wine store. Commercial producers buy low-quality wine off the bulk market, so you’re already at an advantage.
The bacteria need oxygen, but that’s easy to get. Leave your vinegar container — a large glass jar if you don’t want to shell out for a barrel — open to the air, covering any openings with cheesecloth to keep out the little circus of wine flies you’ll soon own. I periodically — once a day when I’m fretting and once a week when I’m not — whisk the vinegar into a frenzy to give the culture a bit of a rush, but plenty of people don’t do that. (Industrial vinegar makers do essentially the same thing, whirring the liquid with a rotor to drastically increase the surface area of oxygen in the liquid. They can change wine into vinegar in just a day!)
Acetobacter also likes to eat. And though they’ll chomp away happily at some alcohol, too much will kill them. The actual tolerance varies by species, but I try to never add liquid that’s more than ten percent alcohol by volume. You’ll quickly realize that no one makes wines with that little alcohol, so I dilute my wine with water until it’s the right level.
The math on this is easy. Round off your alcohol percentage, say 14.5 percent, take the number in the ones place, multiply by ten, and that’s the percentage of water you need to add to your wine before adding it to the vinegar. For instance, that 14.5-percent wine rounds to 15 and thus needs 50 percent more water relative to the wine. No need to get out the gradual cylinders here, though. I just eyeball it in a measuring cup and err on the side of more water.
Note that there’s a one-to-one correspondence between the alcohol level and the level of acidity. A ten-percent wine vinegar will become a ten g/L vinegar, about twice as acidic as commercial brands. In other words, when you’re using your own vinegar, don’t blindly add whatever a recipe calls for. Add to taste.
Every vinegar maker I’ve heard about seems to treat their vinegar stash differently. I’ve read that Alice Waters pulls vinegar out of her barrel when she needs it. Some people bottle theirs. Some bottle it after filtering or pasteurizing it. I strain mine through cheesecloth into bottles and then leave the bottles in a cool spot for six months to mellow.
And how do you know when it’s done? I just go by smell. I smell my batches regularly and when they smell like vinegar and not nail polish remover — the result of ethyl acetate, which the bacteria can also make — I consider them done. Six weeks or so is usually enough, though I’ve had some go two months. I leave about one-third of the batch in the container and add more wine to start the process again.
These days I keep red-wine and white-wine vinegars going. I’ve had some batches go bad (a fungal infection in my barrel, stuck transformations that leave the batch smelling only like nail polish remover and never like vinegar), but I’ve always just picked up and started again. As food preservation goes, vinegar is one of the most casual, least labor-intensive, and least finicky projects I’ve ever undertaken.
And you won’t believe how amazingly good it is.