Tomato vinegar is made through a two-stage fermentation: first, yeast converts the sugars in tomato juice into alcohol, then bacteria convert that alcohol into acetic acid. The whole process takes roughly two to three weeks, requires no specialized equipment, and produces a tangy, savory vinegar that works beautifully in dressings, marinades, and braises.
The challenge with tomatoes is that they’re low in sugar compared to fruits like apples or grapes. Tomato juice typically measures around 5 °Brix (a scale of sugar concentration), which is only enough to produce about 2.5% alcohol. That’s borderline for making vinegar with any real bite. The fix is simple: you add sugar to the juice before fermentation begins.
What You Need
The ingredient list is short. You’ll need ripe tomatoes (the riper the better, since riper fruit has more sugar), granulated sugar, yeast, and optionally a vinegar mother or unpasteurized vinegar with live cultures. For equipment, you need a blender or food mill, a wide-mouth glass or ceramic jar, cheesecloth or a tight-weave kitchen towel, and a rubber band.
Avoid metal containers at every stage. Acetic acid reacts with metal and will give your vinegar an off taste and potentially leach harmful compounds.
Preparing the Tomato Base
Start with about 2 kilograms (roughly 4.5 pounds) of ripe red tomatoes. Wash them, remove the cores, and blend them into a smooth juice. Strain through cheesecloth if you want a clearer vinegar, though leaving some pulp in won’t hurt the fermentation. You should end up with roughly 1.5 liters of juice.
Now address the sugar problem. To get enough alcohol for a proper vinegar, you want to bring the sugar content up to around 10–12 °Brix, which means roughly doubling what the tomatoes provide naturally. Add about 4 tablespoons of white or brown sugar per liter of juice and stir until dissolved. Brown sugar adds a slightly deeper, more caramel flavor to the finished vinegar.
Stage One: Alcoholic Fermentation
This first stage turns sugar into alcohol. You have two options for getting it started.
The reliable route is to add wine yeast, sometimes sold as champagne yeast at homebrew shops. Dissolve the yeast in a small amount of warm water (around 30°C) to activate it, then stir it into your sweetened tomato juice. A little goes a long way: about 1% of the total weight of your juice, so roughly a teaspoon per liter.
The wild route skips the store-bought yeast entirely. Tomatoes, like apples, carry wild yeast on their skins (that faint white dusty film you sometimes see on fruit). If you leave sweetened tomato juice in an open container covered with cheesecloth, wild yeast will eventually colonize it. This takes longer and is less predictable, but it works.
Whichever method you choose, seal the jar with an airlock or cover it tightly with cheesecloth. You want to let carbon dioxide escape without letting flies in. Keep the jar at a steady temperature around 30–32°C. A warm kitchen counter or the top of a refrigerator often works well. Fermentation typically takes 5 to 7 days. You’ll see bubbling in the first day or two, and the liquid will start to smell mildly alcoholic. When the bubbling stops, the sugars are mostly consumed and you’re ready for stage two.
Stage Two: Acetic Fermentation
Now you convert the alcohol into acetic acid, which is what makes vinegar taste like vinegar. This stage needs a different microorganism: acetic acid bacteria. These bacteria are aerobic, meaning they need oxygen to work, which is the opposite of the yeast in stage one.
The easiest way to introduce them is to add unpasteurized apple cider vinegar “with the mother,” the kind sold at health food stores. Pour in about half a cup per liter of your fermented tomato liquid. The cloudy strands in the bottle are colonies of live bacteria that will colonize your batch. You can also use a piece of vinegar mother from a friend’s batch or a previous vinegar project.
You don’t technically need to add anything. Acetic acid bacteria exist naturally in the environment, and if you leave the alcoholic liquid exposed to air, they’ll find it on their own. But adding a starter culture speeds things up significantly and reduces the window where something could go wrong.
Transfer the liquid to a wide-mouth jar (more surface area means more oxygen contact) and cover it with cheesecloth secured by a rubber band. Place it in a warm spot, ideally around 30–35°C, out of direct sunlight. The bacteria need consistent airflow, so don’t seal the jar.
Over the next two to four weeks, the liquid will gradually turn more acidic. After a week or so, you may notice a translucent, jelly-like disc forming on the surface. This is a new vinegar mother, a mat of cellulose produced by the bacteria. It’s a sign that everything is working. Don’t disturb it.
How to Tell When It’s Done
Start tasting after about two weeks. Dip a clean spoon in and smell it first: you should get a sharp vinegar tang with a distinct tomato undertone. If it still smells noticeably alcoholic, give it more time. The flavor should be bright, sour, and clean.
If you have pH test strips (available cheaply at homebrew or pool supply stores), check the acidity. Commercial vinegar sits at around 5% acidity, with a pH typically between 2.4 and 3.4. For a safe, shelf-stable product, you want to reach at least that 5% acidity mark. Industrial processes can achieve this in as little as 24 to 48 hours with forced aeration, but home fermentation at natural oxygen levels takes longer.
One important note: Penn State Extension advises against using homemade vinegar for canning or pickling, because the acidity of home batches is inconsistent and may not reliably prevent microbial growth. Your tomato vinegar is great as a condiment, dressing ingredient, or cooking acid, but don’t rely on it for food preservation unless you’ve verified its acidity with a titration kit.
Straining and Bottling
Once the flavor and acidity are where you want them, strain the vinegar through a fine-mesh sieve or cheesecloth to remove sediment and any pieces of the mother. If you’d like an especially clear vinegar, strain it a second time through a coffee filter, though this can take a while.
To stop fermentation and stabilize the vinegar, you can pasteurize it by heating it to 70–75°C for about 10 minutes. This kills the remaining bacteria and prevents the vinegar from continuing to change in flavor or developing new mother cultures in the bottle. Let it cool completely before bottling. If you prefer a raw, unpasteurized vinegar (which retains live cultures), skip this step but expect the flavor to continue evolving slowly over time.
Pour the finished vinegar into glass bottles with tight-fitting lids. Ceramic containers also work well. Store them in a cool, dark place like a pantry or cupboard, ideally between 10 and 15°C. Avoid windowsills, spots near the stove, or anywhere with temperature swings. Refrigeration isn’t necessary and can actually dull the flavor and cause cloudiness. Stored properly, homemade tomato vinegar keeps for well over six months.
Mold vs. Mother: What to Watch For
During the acetic fermentation stage, you need to distinguish between a healthy vinegar mother and mold. A vinegar mother is smooth, pale, and rubbery or gelatinous. It forms as a continuous disc on the liquid’s surface and may be white, beige, or slightly translucent. It won’t smell bad; it’ll smell like vinegar.
Mold, by contrast, is fuzzy. It often appears as distinct spots of white, green, blue, or black fuzz sitting on the surface. Mold typically means something went wrong early in the process: the alcohol level was too low, the environment was too cool, or a contaminating organism got a foothold before the acetic bacteria could dominate. If you see fuzzy growth, discard the batch. A slimy or smooth film, on the other hand, is almost certainly your mother doing its job.
Using Tomato Vinegar
Tomato vinegar has a savory, umami-rich quality that sets it apart from apple cider or wine vinegar. It’s particularly good in vinaigrettes for salads that already include tomatoes or roasted vegetables. A splash in gazpacho or tomato soup adds depth without additional tomato flavor piling up. It works as a deglazing liquid for pan sauces, pairs well with grilled meats, and can brighten a pot of beans or lentils in the last few minutes of cooking. A small amount stirred into Bloody Mary mix replaces both the vinegar bite and some of the tomato juice.