Why would you make your own vinegar at home? Well, as with most food products, the homemade version tastes better than a mass-produced, store-bought version -- homemade wine vinegar will be stronger and more concentrated, with a more delicate, complex flavor.
It also makes a nice gift or hostess present. You can (and should) start with a higher-quality wine than is surely used to produce store-bought brands.
And it's quite simple to make. Perhaps you've even accidentally made wine vinegar in the past by leaving an opened bottle of wine out too long (this clever wine-resealing device can help you to avoid that, by the way, if you'd rather drink that wine!).
To start, you will need a good-quality wine (red or white) that's not too strong (about 10 to 11% ABV) because too much alcohol inhibits the activity of the bacteria that transform the wine into vinegar. If the alcohol content is too low, on the other hand, the vinegar won't keep well.
There are several ways to proceed:
1. The simplest is to leave an open, 3/4-full bottle of wine in a warm place for a couple of weeks.
It's really that simple. This technique yields just one bottle, however.
2. For a steady supply of vinegar, pour 1 quart (4 cups) of wine and 1 cup of vinegar into a wide-mouthed glass jug with at least 1 gallon capacity. Keep the container sealed with a lid, but open it for a half hour every day to let it breathe.
In a couple of weeks the madre (mother), a viscous starter, will have settled to the bottom of the jug, while the vinegar above it will be ready for use. Add more wine as you remove vinegar for use, to keep the level in the jug constant.
3. If you want to make wine vinegar in larger batches, you will need a 1-gallon (3.78-liter) cask that has a spigot at one end. If it's new, rinse it with vinegar and let it dry.
Next, fill it to within a couple of inches of the top with wine and place it, unsealed, in a place that's about 68 degrees Fahrenheit (20 degrees Celsius). In a couple of weeks, the wine will be vinegar. Drain it from the cask using the spigot. Replace the vinegar removed with more wine, adding it into the cask through a length of hose or a funnel, so as to leave the mother undisturbed.