Does vinegar spoil and how?

Reginald SmithHealth & Wellness, Making Vinegar, Recipes & Tips, Uncategorized, White Distilled/Spirit Vinegar28 Comments


In Google, type in “does vinegar spoil?” and a variety of results pop up. While responses vary in length and detail, the general consensus is “no”. This consensus is generally accurate, with a few caveats, that I will explain below.

The source of most information about vinegar’s shelf-life comes from a statement on the website of the national association of vinegar manufacturers, the Vinegar Institute. In the interest of full disclosure, I will mention that as a vinegar manufacturer I am a member of the Vinegar Institute. The Institute conducted studies on the shelf-life of vinegar as it relates to its acidity–the most important measure of its shelf-life. Standard vinegar is 5% acidity and 4% is the minimum allowed for sale per FDA guidelines.

What the Institute found was that vinegar has a nearly indefinite shelf life (read: years) and though color may change and sediment may form, the safety of the vinegar was not compromised though the taste and quality may change. This is correct since the main component of vinegar, acetic acid, is relatively stable under the right conditions. Vinegar makers have long known this.

Many fine vinegars are aged for years, if not decades. Balsamic Vinegar of Modena IGP is required to be aged at least 60 days before sale. The high-quality expensive Traditional Balsamic Vinegar of Modena or Reggio-Emilia (DOP, not IGP) is required to be aged at least 12(!) years. It costs $100+ for a reason. Similarly many Chinese vinegars like Zhenjiang (Chinkiang) and Shanxi vinegars are aged 3-6 years for various products. Aging actually enhances the flavors of vinegar, especially if done in certain wood or ceramic containers.

So in the spirit of legal liability I will state that the below is for educational purposes only and not a definite statement of any vinegar I (or another manufacturer) makes:

Now, if you buy vinegar in any store, typically you will see a “Best By” date. This date, by convention, for most manufacturers is two years from the production date. This date is a recommendation to distributors, retailers, and consumers about recommended life for the vinegar. Mostly it is for liability and guarantee purposes and not related to any chemical or biological degradation process. While vinegar can keep for years, no one wants their vinegar sold or returned a decade from now, especially if they don’t know how it has been stored.  So while no one will warranty or recommend you use vinegar past its Best By date, it is possible it is still good.

The longest shelf life is white distilled (a.k.a. spirit vinegar) since there are few other organic compounds to cause random reactions to affect quality. Other vinegars can last as long if the acetic acid content is stable but can have various changes over time. What types of changes?

Color: if you look at the back of most non-organic, non-raw red wine vinegars you will see “Contains Sulfites”. While this is no different from similar declarations on most wines, you would be forgiven for thinking the sulfites were only a byproduct of the original wine used. When vinegar makers use wine, we typically want to eliminate or minimize sulfites since their very purpose is to inhibit the bacteria that make vinegar. However, when red wine vinegar is made by modern processes like the submerged vinegar manufacturing process, its color tends to not be stable.

After red wine vinegar is made, sulfites are added to help keep the vinegar’s color stable through its shelf life. Otherwise it turns a light red over time, looking like reddish apple juice. If you ever want to test this, pour some cheap red wine vinegar into a jar, add a few drops of hydrogen peroxide and wait about a week. The hydrogen peroxide removes the sulfites and the vinegar color will soon change from its nice red. This change is harmless though and does not affect the acidity of the vinegar.

Other vinegars can change color too, often by a process known as the Maillard reaction. There are residual sugars and amino acids in many fruit vinegars that will cause a browning over time not completely dissimilar to the browning you see when you bake food. This can take months if not years though to happen.

Sediment: many vinegars are ultra-filtered to make them clear, but this also removes some flavor and nutritional compounds. Those vinegars that are not ultra-filtered can form sediment over time as floating particles settle. Also, some dissolved compounds can slowly precipitate (become solid and sink) due to the slow progress of the reversible rate of the dissolving in solution. This is all harmless as well.

Mother: most vinegars are pasteurized unless stated otherwise. For those vinegars without mother, sometimes pasteurization is incomplete or they are re-inoculated with vinegar bacteria from the air after opening. If there is any residual alcohol (0.2% – 0.3% residual alcohol is an industry norm), a mother will slowly form and likely sink. This is harmless as well and some would even argue beneficial.

So the above quality changes are common but do not affect the vinegar’s safety and use. So how can vinegar spoil and become unsafe to use? There are a few main processes which while not common, should be protected against to maximize the vinegar’s shelf life.

Overoxidation: the vinegar bacteria consume alcohol to make vinegar. Alcohol is their food source so you would be believe they lay down and die when the alcohol is substantially exhausted. This is not always so. Some species of vinegar bacteria can engage in a type of metabolism called overoxidation. This is a process by where once they run out of alcohol, they can begin consuming acetic acid and leaving only byproducts of water and carbon dioxide. This gradually dilutes the acetic acid, eventually lowering acidity to a danger zone where bacteria and mold thrive. This is generally only a problem in vinegar manufacturing but can affect home vinegar over long time periods.

Raw vinegars or homemade vinegars are particularly susceptible since they have active bacteria cultures. Raw beer or raw malt vinegar is the worst in my experience since the heavy nutrients of beer give the bacteria plenty of extra push. To prevent overoxidation you have two options:

  1. Pasteurize the vinegar by heating it at 140 F for 30 minutes. This kills the bacteria and will prevent any additional fermentation
  2. When storing for long periods, store in a jar or jug that is tightly sealed to air and has limited air space above the vinegar in the jar or jug. Without oxygen, the bacteria can’t metabolize anything and this drastically extends shelf-life. When aging, vinegar is removed from most oxygen for this very reason.

Inappropriate storage materials: vinegar should typically only be stored in stainless steel, glass, food safe plastic (HDPE or PP only), or wood. Anything else, especially metals like copper, brass, iron, or aluminum will cause problems. Acetic acid will corrode the metal, reacting with it to form salts called acetates. Not only are many acetates harmful, the reaction reduces the acetic acid content lowering the acidity.

Unsealed bottles: acetic acid can slowly evaporate like anything else so leaving a bottle open or not properly closed can gradually lead to lower acidity.

In summary, if you keep your vinegar in a tightly closed container it should keep for a long time. For raw vinegar it is important to limit exposure to air from outside and within the bottle. While a small  to medium sized air pocket in a jar or jug is typically no big deal over shorter time periods (and the vinegar will probably consume it with little change) leaving a relatively small amount of raw, unpasteurized vinegar in an otherwise empty or not tightly sealed container for a long period is not a good strategy as the bacteria could eventually reduce the acidity below usable levels. The less vinegar in the jug, the faster the overoxidation will proceed. For longer term storage transfer this smaller amount to a more appropriate sized bottle with less air exposure.

28 Comments on “Does vinegar spoil and how?”

    1. You can purchase Supreme Vinegar mothers of vinegar on either Amazon (search for Supreme Vinegar mother of vinegar) or call your local homebrew shop. We have wide distribution in homebrew shops across the USA.

  1. Hi,
    Your knowledge is astounding.
    I appreciate your generosity in sharing it.
    I have been making pepper vinegar for years. I start with retail plain white vinegar from the store and then add peppers, garlic, and other spices to make a very delightful mixture. I have some bottles that I made over 20 years ago. Is there a great possibility that these bottles will be dangerous to consume?
    I experiment with other mixtures. One of my favorites is ginger. I have some of this dating back about 20 years as well.
    I just made a basil vinegar yesterday that is sensational.
    Do you have advice on how to insure maximum safety?

    Thank you.

    1. Hi, it is hard to tell without measuring the acidity. If the bottle remained airtight over the 20 years, there is a good possibility it is ok. Email me at and you can arrange to send a sample for testing.

      To ensure long term acidity, keep the bottle/jar tightly closed not allowing any extra air to enter.

  2. Hello… I m worried because I have a large vat (many gallons) of raw apple cider vinegar I used to infuse some roots and spices and, while I placed a lid on it and strapped that lid down with a ratchet strap, it’s not airtight. It has been three months now and I am going to bottle it immediately. Do you think that three months is enough to have decimated that vinegar or is it still salvageable? Thank you!

    1. If it is a large vat and strapped down, it may still be ok after 3 months. Even if it is not airtight, check to see how big a mother has formed since that will tell you roughly how hard it has been fermenting. If there is not additional mother, fermentation may have been very slow and you might be ok. Check the pH. If significantly higher than 3.5 you may have issues. The best thing to do honestly is ship a small sample to a wine lab that will measure acidity for about $20. That way you can be certain.

      1. Hi, I had remnants of wine bottles that I put in a large glass container in the laundry room some months ago. The container is covered on top with only cheesecloth. We’ve been monitoring the smell and we’ve tried the contents against store bought vinegar this morning. It’s certainly got a high acidity but is richer and more colorful than the store bought. Wondering how to check it’s actually become “wine vinegar” and at what point we should be bottling and sealing it from the air or can it be kept open as it is?

        1. Hi, I think it is already wine vinegar. The only way to test if vinegar is “ready” is to send it to a wine lab to measure titratable acidity or measure it yourself with a wine testing kit. It should be minimum 4% but between 5-6% is best. If it tastes acidic and the pH is below 3.5 then it could be used for anything except canning relatively safely.

  3. Firstly thank you for your site and the informative information. I understand why leaving ageing vinegar open to air, could eventually turn to water. How do the Balsamic manufacturers manage to counter this, as they age their vinegar for years, in open wooden barrels? Does it have something to do with the refilling process? Would love to hear your thoughts on this.

    1. Hi, thanks for your comment. You are correct that for balsamic vinegar sometimes a river stone or cloth is the only thing covering the bung hole. To my knowledge, the main reason the bacteria do not oxidize acetic acid to water is that once the alcohol runs out in balsamic vinegar fermentation, they have another food source besides acetic acid. Since balsamic vinegar has such a high content of simple sugars (i.e. glucose), the bacteria metabolize these instead to gluconic acid. Overoxidation is not necessary. Most vinegars have very low sugar contents so the acetic acid becomes the food source.

  4. My daughter left red wine vinegar out in the car for a day, in 100° heat. She also realized the caps were not totally on and there was some leakage. Are they still good, or should we toss them?

    1. It will be fine. It takes weeks for overoxidation to ruin a batch. Close it tight and place it back in the cupboard.

  5. Hello.. I have recently made my first vinegar using green grapes from our home by washing them and separating them then I let them dry and put them in jars and plastic bottles with leaving enough space for oxygen then I closed them with cloth tissues and elastics and left them for 40 days then I filtered them well into plastic bottles I do not know what is their type (I have glass bottles bu I was afraid because their caps are made from metal) and I am afraid that my vinegar stay contains alcohol because at the begining the bottles were shrinking (I thought they need oxygen) and now everytime I open the bottle a sound of air or gaz gets out of the bottle like when you open a coca cola bottle and today when I opened a bottle I heard that sound too and then it started to effervesce and it spilled everywhere I do not know whether my vinegar is good or I have to discard it because I am afraid of poison my father who loves vinegar or to drink alcohol because I am muslim. Thank you so much for your efforts and I hope you can answer me soon.

    1. Hi, quick question, did you cover the dried grapes in water? I think so I just can’t tell exactly from your post. If your jar is releasing gas upon opening it is still fermenting to alcohol. Best to let air into the bottles (though cover the openings) to let alcoholic fermentation finish and vinegar fermentation start. A key sign of vinegar fermentation is the formation of a mother of vinegar on the surface of the liquid. Once you get that leave it for about 6-10 weeks to complete vinegar fermentation.

  6. Awesome info. Grateful for this webpage.
    Question, pls. Is PET a bad plastic for storing vinegar? I was alarmed when you only mentioned HDPE and PP.

    1. It is FDA approved and is the default for most supermarket vinegars below 1/2 gallon. There is controversy around plastics I will not get into since it is not my expertise but for home vinegar making, HDPE is the most agreed upon best material. PET bottles are hard to clean anyway and should not be reused.

  7. I left a jar with a mother (commercially purchased) , red wine, and water covered with layers of cheese cloth…and truly forgot about it.
    When I opened it up, there was red liquid…at good inch, no bad odor, and what looked like mold floating on top of the red liquid.
    Not sure what to do…
    Is the “mold” just the mother? My guess is the”vinegar “ is safe…but that’s just a guess .
    Do I toss it or?
    Thank you

    1. By last do you mean maintain acidity? If it is kept in a closed container, the vinegar strength should not deviate. If mixed with dishwashing detergent it will probably maintain even if not closed to air since the detergent kills the acetic acid bacteria.

  8. I found (4) 1 gallon jugs of top off wine in the our cellar. 2 were remnants of Grape wine making and 2 from Elderberry wine making. The jugs are dated 2008. The wine ones were covered with plastic and rubber bands. The elderberry had air locks, but the water had evaporated. I strained the grape wine ones, resulting in a liquid that smells like a sweet vinegar. I think we have a balsamic -type result. The elderberry wine had a very large Scoby- like we get on Kombucha only this one weighs about 5 lbs. . The strained liquid has a sweet smell. When it settled out, a wet b brown crumb like residue is at the bottom, but a thinner liquid is on top. Both grape and elderberry liquids are dark brown. The elderberry smells slightly sweeter than the wine one. Do these sound like consumeable vinegars?

    1. Hi, you need to measured acidity to see how “done” they are. They should be at least 4% acidity. We offer such a service for a small cost or you can use a local wine lab but tell them that they should measure titratable acidity only assuming acetic acid. My guess, however, is that it is probably decent vinegar though the evaporation of liquid in the elderberry may have influenced things in ways that are hard to predict.

  9. I made pear vinegars this fall the ph ranged from 2.4 to 3.25 .most have lost their acidity and around ph 4.0.
    When the ph was around 2.5 to 3.0 could I have added. Potassium sorbet to keep the acidity and still have the probiotic in tact.?
    If so how much per gallon?
    ?2. Are there any probiotics left when the ph is over 3.5?

  10. Hi. I have 3 bottles of herbed vinegar about 25 years old band am wondering if they are still edible?The herbs have remained in the bottle and the seals are cork and wax. Fluid levels have remained constant, with about an 8th of an inch of air at the top.
    The whole herbs have gone from their initial vibrancy to a greenish brown color, and have fragmented. The vinegar appears fairly clear. Thanks, Dianne

    1. Hi Dianne, I can’t say anything for certain but it very well could be good still. I would take a 100 mL sample and send it to a wine lab to measure titratable acidity. If over 4% you are good.

  11. Hi there, very helpful website I must say. I use an organic unpasteurised balsamic vinegar to make a fig balsamic. I buy the vinegar in bulk , so a gallon, but I don’t normally use all of it at once. I normally cook the vinegar and remove it off the heat 5 mn after it has reached a boiling point. I then marinate the dry figs and spices for a couple of days before processing it and bottling ( bottles are sterilised). In your opinion, what would the shelf life be. I normally keep my bottles in the fridge and they last at least 6 months if unopened. I would love to hear your thoughts on that.
    I live in London and I am about to open a cafe where i can market my dressings. I will be sending some samples off for testing but was wondering whether there is something i should be aware of in order to get a good outcome.
    Thank you

    1. Hi, thanks for your comment. Balsamic vinegar shelf life, like all vinegars, is theoretically indefinite but industry practice is two years for the best by date. Final acidity should be at least 4% but most balsamics are around 6%.

      You mention 6 months and spoilage. If they are kept closed, the vinegar should be fine, even if not refrigerated. Make sure pH and acidity are good and in line with UK regulations before marketing it since it shouldn’t go bad if kept closed.

  12. I think I just experienced the effects of overoxidation! I have a very small quantity (about 300ml, which is perhaps my first mistake) of raisin vinegar I’ve been making. It was very boozy after fermenting the raisins, and as I’ve been tasting throughout the acetic acid fermentation process, tasted at one point quite like a strong malt vinegar. It’s only been going for about two months, but when I tasted today, there was NO vinegar flavor left! It just tasted like a bland, watery, kinda gross flavor, not too dissimilar to that band-aid flavor that some Hefeweizen beers have.

    Did my low volume allow for expedited evaporation of the acetic acid? Is there a method for knowing when to stop the alcohol to acetic acid conversion so that you don’t go too far? What’s weird is that it still had a mother growing on it…

    1. Yes, the low volume made the fermentation go much more quickly. It is not so much acid evaporation as it was the rapid fermentation due to the small volume. This often happens if you store vinegar in bottles with low liquid level or a non-airtight seal. Once it tastes strong you should test acidity to see where you will need to stop. Testing acidity should be done via titration such as a wine kit or a local wine lab that tests titratable acidity.

      To stop fermentation put it in as small a bottle as you can to fill up most of the volume and close it with an airtight (preferably screw) cap.

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