My vinegar smells like acetone (nail polish remover)!

Reginald SmithAll About Vinegar, Making Vinegar46 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.

46 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.

      1. Even, I make my ACV just the way Sharon did. After 7-8 weeks it smells like alcohol but when diluted with water, the taste is okay. I have started selling it as well. Is it a good idea to sell Homemade ACV or is there any commercial idea to do so. I am from Nepal (South Asia). Sometimes I make it a Glass Jar and many times in a Plastic Jar.. Does it affect as well?? Kindly, suggest. Thank you

        1. The good news is there is no health or safety issue from this smell. The most likely cause is that there is a bit higher residual alcohol in the ACV than you might want. When the jar is closed, the bacteria try to metabolize this alcohol to acetic acid but cannot since the closed lid limits the oxygen. The fermentation becomes stuck and gives off an alcohol/nail polish removal smell. Typically for raw vinegar limit the final alcohol to less than 0.5% ABV, 0.2-0.4% ABV is best. Are you capable of measuring acid and alcohol content yourself? If not are there food/wine labs in Kathmandu that can do it?

    2. What can I do with 5 gallons of hononey vinegar that smells like acetone?! Is there an alternative use?

      1. You can dilute it down to water to a Brix around 1.06, add yeast to ferment to mead and then add mother (raw vinegar + solid mother) at 1/4 volume to ferment honey vinegar.

  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).

    2. Hi,

      I had a peculiar situation when making my apple cider vinegar.
      The first batch I made came out pink.
      I’m wondering if it’s due to the Apples I used, which were red, or if it’s due to mold or a water born bacteria, Serratia marcescens. Please advise. Thank you.

      1. Probably due to the apple skins. If alcoholic and acetic fermentation proceeded properly and at a good pace, other bacteria should not have been able to grow.

        However, if there is a foul odor or fuzzy residue on the mother, it is spoiled by mold so should be dumped.

      2. Hi my fermentation seems to gone wrong with mostly white fuzzy and one black patch. It’s floating on top(two months of fermentation at 25 celcius. Should I just remove it and continue?

        1. Hi, this is probably mold if it is fuzzy. You have to dump it, sterilize the jar, and start over.

    3. I just strained the apples smells like turpentine should I put apples back in jar and leave a few weeks

      1. The apples in the jar may be part of the problem if they are impeding the formation of mother or airflow. Leave them out and make sure the vinegar is open to air and see if it improves after a couple weeks. If you added a lot of sugar and the alcohol is high, the problem may persist. Increase water content by 25% and this should dilute the alcohol enough to not impede fermentation.

    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.

    2. Okay need help. So I had 2 batches or acv going. One that was sugar. Apples. And filter water in a jar, it grew a beautiful mother. The second was based off some random woman’s blog post same ingredients but the jar was sealed……which led me here because it developed a STRONG acetone smell. Soooo here’s what I did. Mixed the two, added more fresh apple. And divided the very thick mother between the two like you would a kombucha scoby. Do you think I just destroyed both batches? Or do you think the mixing of the two plus new food might save them????

      1. Hi, if you had just removed the lid of the second batch and covered with a cheesecloth or other air permeable covering you could have just done that and been ok most likely. You probably did not destroy the batches though. The acetone smell was because the vinegar was starved of air and could not complete the conversion of alcohol to acetic acid. Keep monitoring them and both batches should be fine.

  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.

  8. After first stage fermentation (2 weeks – strong alcohol smell after 10 days) and straining off the fruit From my gallon jars, I am seeing a white film covering the liquid in about 4 days and a strong smell of acetone – I do not see any reference to the white film in your former inquiries – I see suggestions to add a tablespoon of vinegar with mother or a couple grams of brewer’s yeast and stir – what do you recommend? How often should I stir? Do I need to worry about the white film? If I try to spoon it off it breaks up into the liquid.

    1. Hi, how strong was the sugar at the beginning? If you have a strong alcohol smell the most likely issue is the alcohol content is high so I would dilute your mash. You don’t have to add raw vinegar, just add about 1/5 by volume of water to lower it some and see if that improves things. You need an ABV under 10%, preferably under 8%.

      The white film is likely a type of mother (some can appear like this) but it has issues forming perhaps due to the strain of fermentation in high alcohol conditions.

  9. Hey there, I am hoping you are still answering these questions/comments, as it seems you are pretty thorough and “on it.” Here is my method

    I juiced apples (after removing much of the wax they put on for display, by dipping into boiled water and rubbing with dry cloth) and placed into large 1.5gal with cider brewers yeast and topped it with an airlock to produce the alcohol. (Perhaps too high ABV) and stopped the process when the bubbles stopped activating the airlock. Then I put in a mother that came with it’s vinegar in a 6oz jar. it’s been 4-5 weeks now and a decent mother had formed about 1/4inch thick. After the 2nd or 3rd weeks I added about 1/4 cup of Braggs as well because the mother was slow to form. I also have had a cheese cloth toed around the top and put the plastic lid on (it has about a 1 inch diameter hole in the middle) so perhaps I started by making the ABV too high and followed that by restricting the oxygen with the cheese cloth + lid combo. My biggest concern is when I go to fox the errors, and I have to move the mother, she will no longer float on top and create that barrier from the air… what do you suggest ?

    1. Hi, yes I am still answering questions! So if you used juiced apples I highly doubt the ABV was too high, even if it was fermented dry (no sugar left) as you suggest. For apple juice, getting higher than 6% ABV is rare. If the mother has grown and is on the surface it should be fermenting nicely. The air hole should be sufficient, only the surface area of the mother is a limiting factor if there is even a small hole for air in the lid. Don’t worry if the mother falls, it should re-form as long as there is alcohol left.

      Now you may want to remove some to test to see when it is done. For information on the differences in pH and acidity see this link. A wine lab can do titration for you. Let me know if this helps.

  10. Hi Reginald.
    Cracking post.
    So, I’ve got a lovely ACV and mother going, she’s a beauty and I’m very proud.
    However…I’m a bit concerned about my attempt at red wine vinegar, she’s in a glass jar, lidless but covered with muslin. She pongs of cheese…and not in a good way, she has had scaley looking flakes, some sdiment and possibly a grey looking moldy film.
    Can you please help me?
    A)is the smell normal?
    B)Is it a problem?
    C) if it is a problem can I fix it?
    D) Should I obtain red wine mother from somewhere and start again?
    Thank you in advance
    Lou x

    1. The bad cheese smell and moldy film are strong evidence mold has seized the fermentation. Unfortunately there is no cure for this but to dump it and sterilize the vessel to start over. When starting vinegars, it is best to add raw vinegar in addition to the mother at about 1/4 of the volume of alcohol you want to ferment. Not only does raw vinegar have a lot of bacteria to help fermentation, it lowers the pH and raises the acidity making it inhospitable to mold.

      You can use your ACV mother to start it while adding a bit of regular vinegar to protect against mold but you may not want your ACV mother to sink until it is done so you can wait to use that fermentation or get a new mother.

  11. Thanks my friend. Ahhh tis as i feared :-/
    We shall forge ahead having dispatched the funky brew.
    Cheers and all the best (I’m sure I shall be in touch Lol)

  12. Hi Reginald. What a great find your site is.
    I am new to learning about vinegar making but have made some very passable vintages from apple scraps and raisins in the past. Now I have discovered about vinegar mothers and two stage fermentation etc. I seem to be rather less successful.
    I have been given a big jar of freshly pressed apple juice (which actually tasted rather watery) so I added a couple of tablespoons of brown sugar and put it to ferment. It developed fairly rapidly in my warm kitchen and eventually got covered with a delicious smelling yeast..
    When it had stopped bubbling I strained it to remove the yeast and then covered it with kitchen towel to ‘vinegarise’. It has become fairly acidic but the yeast has formed again and I see no signs of a mother forming.
    What does this mean for the flavour of my vinegar, but more importantly, will it be safe to drink or will we get digestive problems from the yeast?
    I have managed to order a bottle of raw ACV with mother for future trials, but would love to know about this particular issue if you are able to give me some ideas.
    Thanks for your time and consideration.

    1. Hi let the yeast ferment the cider dry (until the bubbling stops). Then a mother will form and it will ferment properly. Dead yeast are not unhealthy and actually have nutrients so I would not worry about it. Next time, after the bubbling is done, add the raw mother and ACV to jump start vinegar fermentation.

  13. I had this happen due to lack of oxygen. Will it fix itself now that I’ve opened up the jars? Or does lack of oxygen create too much acetaldehyde to overcome?

  14. Hi Reginald. Great blog, thanks. I have been making ACV for some years, generally in a 55 gal open top drum. We make hard cider so I put fully fermented cider into the drum, add mother and let it sit until done. This worked well for several years. Since we needed a bit more ACV (we sell it in our farm store), I took an IBC tote which was about 2/3 full (roughly 175 gals) of fully fermented hard cider, added mother and put in an aquarium bubbler with multiple diffusers with a fine screen over the 6″ hole at the top of the IBC. All I got was really weak vinegar with an acetone flavor and no mother formation. Reading over previous posts, it seems the problem could be lack of air, owing to the inability of the liquid to absorb enough oxygen from the bubbles. Wondering your thoughts. Could also be a temperature problem — I struggle to keep the IBC over 65-70 degrees F. Is there a definite temp that is too low? Thanks

    1. Hi, here is my take after years of experimentation—you see the aquarium bubbler tip a lot on the Internet but I have yet to see it work practically at scale. The issue is, even with a diffuser stone, the oxygen absorption in a typical container is low unless you are using a column. There is a commercial bubbler method but it requires tall pipes with high length to surface area ratios since it takes a long length for enough air to be absorbed.

      The bubbles also constantly disturb the surface preventing mother formation.

      The temperature is on the low end but not the end of the world, I have spontaneous fermentation often at that temperature; below 60 degrees seems to be where it grinds to a near halt.

      I would test the alcohol to make sure the bubbler didn’t reduce the alcohol too much and if the alcohol content is still good, just let it rest and see if the mother forms naturally. You may want to add more mother if you have some as well.

  15. Thanks for the reply. For making 300-400 gallons/year of ACV, what type of vinegar production would you recommend? Generator? Diffuser? Orleans?

    1. You could definitely do that with Orleans for minimal investment. Typically for commercial Orleans production, the vinegar is fermented in stainless steel tanks or FDA approved HDPE plastic drums. I would give yourself two months for fermentation and two months for aging (fermentation might get quicker, especially in summer but this is a good start). For 400 gallons per year you need a continuous working volume of 133 gallons of fermentation + aging.

      For the fermentation vessel, you can use an up right 55 gallon drum or steel tank upright to ferment. If you want fermentation faster, use a 53 gallon barrel on its side but in this case I would use 2 53 gallon barrels which will only be filled 2/3 full to allow air and maximum surface area. The lateral surface area is more than the upright and gives the mother more surface area for fermentation. Be sure to clean most of the sunk mother out after fermentations though you can leave some to start the next fermentation.

      Then, when the vinegar is done, fill up a 55 gallon oak barrel (no air space) and plug it to make it airtight for aging. You can use a used spirit (bourbon, rum, etc.) barrel for flavor. That should get you what you need for annual production. Let me know any other questions.

  16. Hi Reginald,

    I’m an experienced homebrewer and have been playing with malt vinegars. After a few successful batches, I’ve started having trouble with acetaldehyde. My method is I mash, skip the boil, and ferment for 2 weeks to land around 5-8% ABV depending on my grain bill. I acetify in a glass 1 gal jar covered with cheesecloth, pitching a hunk of the previous batch’s mother to get it started. After a couple months, the acetone-like smell becomes overpowering, and letting it rest another month or two doesn’t seem to help. Is the answer just even more time? Oxygenate somewhere in the process? Less or more head space in the jar? I get mothers that grow pretty thick, like up to 2 inches and likely beyond if I let them go. Wondering if the thick mother is smothering the vinegar, I’ve tried removing them and letting them reform, but that doesn’t seem to help.

    Also, it’s my understanding that a mother is comprised of cellulose. What is the acetobacter converting (aka what is it stripping from the beer) to make cellulose?

    1. Hi, the two main reasons for acetaldehyde (indicating a stuck fermentation) are lack of air and too high alcohol content. I don’t think either of those should be an issue if your maximum ABV for your starter is around 8%. You also should not lack nutrients since beer/ale are the best nutrient rich vinegar bases in my experience. Thick mothers facilitate bacteria metabolism and usually aren’t the culprit.

      What temperature are you fermenting at? Is it below 70 F / 21 C? This could slow down bacteria metabolism and cause issues too.

      Another thing I would try is instead of just adding a mother to the ale, add about 1/4 to 1/2 volume (relative to ale) raw malt vinegar from a previous batch. This lowers the starting ABV while allowing the final acidity to be the same. You may have (by luck) gotten an acetic acid bacteria with a low alcohol tolerance in your mother.

      You are right, the mother is cellulose and the carbon used to make it comes from the alcohol to an extent but residual simple sugars in the ale are actually what drives mother growth the most. That is why things like malt vinegar can have huge mothers but vinegar from distilled alcohol, not as much.

  17. Hi, Reginal: Just stumbled on your website and I’m brand new to making fruit vinegars. Two weeks ago, I started a raisin vinegar, adding a bit of sugar, covering it with a coffee filter, stirring 1x daily and it does not have an pleasant smell…it stinks. Is it supposed to have a very unpleasant smell? Does it need another feeding of sugar (its got bubbles on top)?

    1. Hi, the ‘stirring’ aspect for making vinegars is a bit overrated, it isn’t really necessary. For starting fruit vinegars you should add brewer’s yeast at the beginning after adding sugar to start fermentation immediately and prevent bacterial spoilage. It probably spoiled since the yeast fermentation to alcohol did not get going before the spoilage bacteria took hold. I would start over, boil the mixture after you make it (before adding yeast or mother) and once it cools to room temperature, pitch in brewery’s yeast. After up to a week of bubbling, the fermentation should stop and then pitch in the mother to start vinegar fermentation.

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