Vinegar is one of those entirely misunderstood but constantly used edibles. It’s mixed into salad dressings and marinades, used as an eco-friendly household cleaner, and even applied topically as shampoo and a skin toner.

But what is vinegar, and where does it come from?

Put as simply as I can, vinegar is the secondary fermentation of sugar. In nature, something sweet like fallen fruit or broken honeycomb will initially be colonized by yeasts, who will convert some of that sugar into alcohol. The alcohol is then colonized by bacteria in the Acetobacter family, which oxidize it into acetic acid, which we know as vinegar.

So basically, vinegar is what happens when a bunch of bacteria decide to get wasted. Fair enough, but that’s not really what’s so cool about maintaining a vinegar culture at home. Oh no, friends, what’s exciting about maintaining a vinegar culture at home – or its cousins kombucha and jun – is that Acetobacter, like the turtles and snails of the bigger world, builds its own house. A giant, gelatinous gooey film that gets larger and larger over time, your very own microbial blob! – known technically as a pellicle.

Vinegar pellicles after harvesting out of Mason jars

The pellicle serves some functions for the Acetobacter chewing away at their little bar below. First, because it forms at the surface where oxygen and alcohol meet, it creates a barrier between the world and the microbe’s food source. This means that other organisms are physically excluded from joining the fray. Unsurprisingly, that big blob is a pretty good “Keep Away” sign for the front door.

Second, the pellicle may help the organisms regulate oxygen to the liquid below. This is important because Acetobacter oxidizes alcohol, creating a chemical reaction that transforms your booze into an acid. This is a fantastic thing if you’re a vinegar brewer, but slightly less cool if you’re into making beer or (especially) wine and end up with a five gallon batch of unintentional sours. It happens.

So how do you make vinegar at home?

What kind do you like? The names are highly descriptive – apple cider vinegar is brewed from hard apple cider, red wine vinegar is made from red wine, malt vinegar begins life as beer, and so on. Rice vinegar includes an initial step with koji to slice up all those long starch conglomerations into little sugar molecules that yeasts can then eat.

If you live in a place that has grocery stores that carry vinegar labeled “Live” or “Raw” or “With the Mother” (Bragg’s is a common producer in the US), you can start there. While the pellicle, also known as Mother of Vinegar (MoV for online shorthand), is an impressive bit of construction, the fact is that unpasteurized vinegar is teeming with the microbes that made it. I’ll write a more thorough how-to later, but for now, try this:

  1. Get a one-quart Mason jar or other decently-sized vessel
  2. Fill it one-quarter full with live vinegar
  3. Top off with cider, beer, or wine (dilute slightly if it’s particularly strong)
  4. Cover with a towel, coffee filter, or other breathable lid, held in place with a rubber band or similar.

Put it out of the way in a warmish area and leave it alone. Some people prefer to brew it in the dark, but I haven’t found a difference. In warm weather, you should have a noticeable skin at the surface in a week or two. For me, brewing in winter means the pellicle may not even form until the temperature changes, but your mileage will vary.

Completed vinegar can take weeks to a few months to finish. I’ll have more on this later, because as much as I love everything I make, dropping acid is especially fun!