My vinegar smells like acetone (nail polish remover)!

Reginald SmithAll About Vinegar, Making Vinegar15 Comments

If you make vinegar long enough you have to tackle almost every problem. I sometimes get emails and questions about an “acetone” smell from vinegar, very similar to nail polish remover. What does this mean?

First, you must understand the process by which acetic acid bacteria turn alcohol into vinegar. The short chemical pathway is:

Alcohol (Ethanol) + Oxygen -> Acetaldehyde + Oxygen -> Acetic Acid + Water

The middle step is rarely discussed because it isn’t of use to the average vinegar maker. Acetaldehyde is an intermediate step on the way from alcohol to vinegar. And if you get my drift, acetaldehyde in concentration smells a lot like acetone.

So the acetone smell is what happens when the reaction to make vinegar isn’t completely finished. Many bacteria just make acetaldehyde and then start creating the pungent odor. The reasons for incomplete reactions can vary but the top two are lack of air (oxygen) and too much alcohol in the starting mash.

Vinegar fermentation requires oxygen and needs a plentiful supply. That’s why a porous (but not porous enough for fruit flies) cloth like cheesecloth is all you want closing up your jar or barrel. Having enough air usually prevents the issues with stalled fermentation.

The other reason is too much alcohol in your starting mash. As has been stated the starting mash should not have an alcohol content exceeding 10% ABV. I would not go higher than 8% ABV if you are using traditional methods. Too high an alcohol content puts stress on the bacteria. They spend too much energy trying to cope with the poisonous effects of high alcohol concentration and don’t have the resources to ferment vinegar correctly, leaving a lot of acetaldehyde. The solution to this is lowering the alcohol content.

Another thing you can do is put a packet of brewer or baker’s yeast for up to 5 gallons of vinegar to provide nutrients to help fermentation.

15 Comments on “My vinegar smells like acetone (nail polish remover)!”

  1. I make my acv with about 3 1/2 quarts of chopped apples, a cup of organic sugar in a gallon jar and fill to the shoulders with filtered water. No added alcohol or yeast. Cover the jar with a coffee filter secured with elastic, and stir1-2 times daily. It is now 6 weeks old and smells like acetone. Do I understand correctly that the acetone smell will not last as fermentation progresses and I do NOT have to throw it out?

    1. You should not have to throw it out. Once the bubbling stops (meaning the end of alcohol fermentation) you no longer need to or should stir it since you need a mother to form. A lack of a mother can limit oxygen absorption and may be the reason for the acetone smell. I say let it stand for a few weeks and it should get better. If not, add a little bit of yeast (1 gram or less) to give it some extra nutrients.

  2. I started a batch of red wine vinegar for the first time about 4 weeks ago. I added about 1 gallon of Red wine and 2 bottles of red wine vinegar with mother. I covered it with cheesecloth for 2-3 weeks and afterwards placed a lid on it. It now smells like nail polish remover and it seems to sweat inside the jar. Reading your post, I made 2 mistakes. 1. I did not reduce the alc content and 2. Did I destroy it by covering it after 3 weeks?
    Can I now dilute it and maybe expose it to some air and it will turn out ok? Worried about mold etc.

    1. Hi, you should not have covered it with a lid but kept on the cheesecloth until the vinegar is done. However, you have not destroyed or ruined it. You should also make sure you cut the wine at least 1:1 wine to water+mother. If the bottles of red wine vinegar with mother were 16 oz I am guessing, add one quart of water and that should bring the alcohol more in line. If you remove the lid and put the cheesecloth back on the fermentation should resume and the acetone smell should disappear.

      If you are worried about mold, instead of a quart of water add a quart of vinegar (red wine or white distilled) so the acidity is low enough to ensure no mold growth. Mold isn’t a huge problem with red wine mother typically unless the wine itself was heavily contaminated with spores (this happens though it doesn’t cause any health problems with people).

    1. No, your body does not metabolize acetic acid into acetone. The components of acetic acid do contribute to fat or carbohydrate digestion but you should still take it in moderation since excessive acid can hurt your teeth and possibly throat/digestive tract.

  3. Hi Reginald,

    Would you field a few questions for me?

    I make red wine vinegar the slow way. When I first start a batch, I dilute the wine with 2 parts wine to 1 part water — I’ve noted that you recommend a 1:1 ratio to bring the ABV down to under 8%, so I may adjust, accordingly. Here’s question #1: It seems like the acetified wine that has been converted becomes the “diluting agent” for all new wine, so after getting production of acetic acid going, I don’t need to continue to dilute wine additions, right? (This stands to reason, especially given your responses to comments above, but I hoping you’ll just confirm this.)

    Question #2:
    Also, I’ve noted that an HDPE container that is open at the top is more efficient at converting alcohol to acetic acid than an HDPE container that follows the design of a traditional Orleans Process (OP) oak barrel. As you know, much of the design of the OP barrel is dedicated to minimizing the disturbance of the mother-of-vinegar (MoV) on the surface. Here’s what’s puzzling to me: when I introduce new wine in the open container, I create a lot of turbulence, which may or may not sink the MoV. If it sinks, I remove it.

    It would seem that the open container method, which may sink the MoV, handicaps the whole acetification process relative to the OP design. However, when I actually test this out, this is not the case. In fact, it’s the opposite: the open container is more efficient than the OP design. I’ve noticed that with the OP design, I still find that the MoV sinks (but maybe not as frequently as with the open container).

    Here are some theories of mine:

    — Maybe the MoV is not as important to the conversion of alcohol to acetic acid as we think. That is, maybe the acetic acid bacteria (aab) in solution is what really drives the conversion process (not the MoV), so the MoV is just a result of this conversion at the surface, where oxygen contributes to the equation.

    — Maybe the open container allows more oxygen to flow across the solution’s surface than the OP design. More O2 overcomes any of other downsides of the open container design.

    *Maybe there is something special about the use of an oak barrel rather than HDPE in the OP design. For instance, maybe oak “breaths” better throughout its contact surface, allowing more O2 to enter the system than just at the surface of the vinegar/wine solution.

    — Maybe the sweating on the “ceiling” of the HDPE OP design drips on the MoV as it forms, which disrupts its development, thereby slowing the acetification process relative to an oak OP design. (I have no idea how much dripping happens on the interior surface of an oak barrel, but I suppose sweat at the top could be absorbed into the wood, somewhat.) In the open container design, there’s no “ceiling” (only cheese cloth), so there’s no dripping.

    I realize there are a lot of variables here, but do you have any thoughts as to why an open container outperforms the OP design as I’ve described? Clearly, oak is much preferring in the aging process and in “rounding out” the vinegar’s sharpness, but I’m only interested in the acetification stage above — not aging. Do you see any advantages of oak over other materials in the initial acetification stage?


    1. Hi, let me give you some feedback:

      Question #1: Yes, after the first batch you only add full wine (sulfites removed) as a diluting agent, you do not need to add any additional water.
      Question #2: You seem to have a very good handle on vinegar making. Here are my questions/thoughts:

      a. For the OP process is the HDPE bucket vertical or horizontal? If vertical with a cover, the open top process will probably be more efficient due to better oxygen flow as you mention. Traditional OP design as a barrel laying on its side. If you laid an HDPE bucket on its side and drilled a hole for air (while only having it about 1/2 – 2/3 full of wine) it should theoretically be faster since there is more surface area contacting air laying on its side than upright.

      b. You are right to remove sunken mother as it might absorb oxygen from the wine and slow fermentation

      c. The mother being important can vary on the species of bacteria present. You do not have to have a mother as you note since bacteria in solution can still do the job. A lot of people who get my mothers ask why it isn’t 100% solid and I let them know even a small amount of mother and bacteria multiply rapidly. I have had multiple cases where the bacteria did full fermentation without a mother. Some acetic acid bacteria don’t form mothers at all (these are mostly industrial strains). It depends on the type of liquid and the bacteria present. All things being equal the mother should accelerate the process by concentrating bacteria and improving gas exchange with the air but a lot of variables go into it. At the end of the day, if it works, it works!

      d. Sweatings on the ceiling can disturb the young mother as you mention which is why a towel or cheesecloth covering is better than a closed lid. You don’t have to cover at all if you aren’t worried about fruit flies.

      e. Oak is good for aging and not necessary for acetification. I know several of the commercial slow-vinegar makers in the US and a common practice is to use stainless steel or food grade HDPE tanks for acetification and only use oak (completely full barrel to stop fermentation) for aging. Also they typically age for vinegar profile flavor not excessive oak flavor.

      I hope this helps.

  4. Thank you for your detailed response, Reginald.

    Both the open top contain and the container that followed the traditional OP design were kept side-by-side, under the same temperature conditions, etc. The open top is vertical, while the OP is on it’s side, creating more surface area than the open top. That’s why I am baffled about the outperforming open top. As you say, if it works, it works.

    Thanks again!

  5. Hi Reginald,

    I’ve gotten into making vinegar at home thanks to the NOMA guide to fermentation book. I bought an aquarium pump and just juice things like apples, carrots, etc. and add vodka. I was hoping you might weigh on a few issues I’ve had.

    1. I’ve noticed that although they claim starting alcohol % = final acetic acid conentration I haven’t found my vinegars to be very acidic. When I compare them to vinegars I buy from the supermarket that are 5% I feel like even if I start with a 6 or 7% alcohol, it won’t taste as acidic as the 5% supermarket stuff. Am I doing something wrong? I’ve looked at papers online and some claim that the conversion rate isn’t exactly 1:1.

    2. After I finish making my vinegar it is absolutely gorgeous. I’ve noticed however that after a few months it develops an acetone-like smell. It really reminded me of nail polish remover which is what led me to this post. What could be happening in my mason jar that could be leading to this problem?

    3. I also notice that sometimes (not everytime) a few days after I finish making a vinegar and putting it in a mason jar, I’ll notive a build up of gas. I’ve spoken to winemakers and they say that it could possibly be malolactic fermentation. What do I do to either avoid this?

    Would love your thoughts!

    1. See my comments below:

      ” I’ve noticed that although they claim starting alcohol % = final acetic acid conentration I haven’t found my vinegars to be very acidic”

      Two things: first, the papers you found are correct. The alcohol % = final acetic acid concentration is the theoretical max according to the formula. In reality you usually only get 0.8-0.9% acidity for every 1% ABV.

      However, taste is not the best way to compare acidity, you should titrate it (or pay $20 to a wine lab who can do it). Commercial vinegar usually isn’t aged long so the sharp taste is also a byproduct of that. Long aged vinegars or vinegars made with slow methods that take weeks or months should not taste as acidic since they age and mature more which reduces the sharp taste.

      “I’ve noticed however that after a few months it develops an acetone-like smell.”

      The acetone smell probably occurs since there is still alcohol left but in the mason jar you keep it in, the air flow or quantity is not enough for complete fermentation so the acetaldehyde builds up. The solution is to either

      1) fill the jar completely with vinegar allowing no air for fermentation
      2) pasteurize the vinegar by heating to 140 degrees to 15 minutes or so
      3) let the vinegar fermentation continue a bit longer to use up the rest of the alcohol

      “I also notice that sometimes (not everytime) a few days after I finish making a vinegar and putting it in a mason jar, I’ll notive a build up of gas.”

      Given you are using vegetables it just might be malolactic fermentation. If your vinegar is at least 1% acid (which I am guessing it is) the yeast should be dead. You can pasteurize as above to prevent this.

  6. I’m at my second attempt and have made pineapple vinegar, however the mother that was on top slowly vanished. It still smells correct like the last batch of ACV I made. It still has a week left, is there something wrong? Should I cover it with a lid instead of the cheesecloth?

    1. By slowly vanished do you mean it sank? Mothers can’t dissolve since they are made of cellulose which is not water soluble. If it was only a film though it could have been a strain that doesn’t make a solid mother and fermentation is still ongoing. If the acidity and taste work out, it should be ok. Don’t cover it with a lid unless you want to stop fermentation completely since the bacteria need oxygen for fermentation.

  7. Hi,

    Which is a better pickle? A well fermented sweetness or a highly acidic one?

    Left my pickles in the fridge for too long and it lost its acidity, so I added some commercial apple cider vinegar to it. Now it tastes highly accidic with an alcoholic stench.

    Personally prefers the acidic one (I use it for cooking) but is worried about the health effect from the excess acetaldehyde.

    1. Hi, whichever is better depends on personal preference. If you used store bought vinegar for the pickles, there will likely be almost no acetaldehyde to worry about and very little alcohol (less than 0.5% ABV). I wouldn’t be concerned about those health effects specifically.

Leave a Reply

Your email address will not be published. Required fields are marked *