I have been trying to make homemade vinegar for the past few months. I have successfully made apple cider vinegar, grape vinegar, pomegranate vinegar and so on.

I recently put a new batch of apple cider vinegar 5-6 weeks ago. It was fine, tasted and looked fine. But 3 weeks ago there was a mold on it, I researched and some said to remove and observe, some said to discard (Similar issue 1 similar issue 2)white mold on top of vinegar. It was a huge batch so I didn't want to discard it. So removed mold and continued. Nothing for a week. Today I checked again and there is a thick layer of mold. The color is fine. But the taste is not acidic at all. There is no sweetness of apples like usual. Nothing special about smell though.

I wanted to ask, is there any way I can salvage it somehow? Strain it completely, add some more apples, sugar, and water and let it ferment? Has anyone tried it? or will it all be a waste? Or do I have to discard it? Please help.

Below is the image for reference.

  • No, it doesn't. Sorry. I have read that (as mentioned in my links). Their's taste fine. They have a mother too. Mine on the other hand is not normal mold. Someone suggested its kahm yeast.
    – Freed
    Dec 4, 2023 at 10:34
  • Certainly looks like Kahm yeast. Which I don't consider a major concern, if you actually have a mother under it making vinegar successfully. But perhaps you don't? See also the old saw about "not putting all your eggs in one basket" with regard to the benefits of not doing one huge batch, but rather multiple smaller ones...
    – Ecnerwal
    Dec 4, 2023 at 14:26
  • "Mold on vinegar" questions pop up on the site fairly frequently - the OP probably didn't find all the old ones. And the answers seem to never be specific about some kind of mold. I have now created (a Meta discussion)[cooking.meta.stackexchange.com/questions/3834/] about how we want to treat these questions. There we can decide whether we as a community have the means and ability to provide custom answers to each such question, or if they should be considered duplicates. There is also my (last answer)[cooking.meta.stackexchange.com/a/3827/4638] about mold questions.
    – rumtscho
    Dec 4, 2023 at 16:49
  • @Ecnerwal I don't have a mother unfortunately. That's why the linked answers were not helpful. Since there is no acidity after approximately 2 months now even though all my other vinegars were acidic even slightly at 3 weeks going. What I want to know is if I add fresh ingredients to it, will it work in saving or will it all be a waste? Plus, the eggs in a basket, as mentioned I have been successful in the production of vinegars previously, of different types even. So i felt confident in going for a bigger batch. But it didn't work out.
    – Freed
    Dec 5, 2023 at 6:11
  • @rumtscho I checked reddit, youtube, google and here. I was not able to find about kahm yeast (someone on reddit told me). Each time I wrote about white squiggly cotton on my vinegar, I was given mold, but images of mold was different from what I had. One person even had worms in their vinegar. So, I tried from my side, but nothing helpful was found. I am in favour of a post with all the troubleshooting issues. Just please make sure that it has images as well so we can match our stuff with it. Thanks alot.
    – Freed
    Dec 5, 2023 at 6:15

2 Answers 2


Rather than adding fresh ingredients to it, I would try your fresh ingredients in a smaller jar by themselves until you get acidity/a mother, and then add the working mother to the difficult batch. Or, ask a fermentation friend for a bit of working mother to get there faster.

However, the yeast will have been eating the sugars in the cider to support their growth, so what you'll get from this batch is unknown. If adding sugar, I'd suggest waiting until after adding a mother.

  • Hmm. Got it. I will try that. I already have mothers of my own from previous batches. I will try that. But I am now a little scared due to what the other person (Sneftel) said. But lets see how it goes. Thanks
    – Freed
    Dec 6, 2023 at 15:54
  • If (as it appears to be in the far-away view) it's Kahm yeast, and your closer examination and removal of it is consistent with it being Kahm yeast, it's not toxic. This stack loves to kneejerk to the most dire remote possibility on any food safety issue, and "you said mold!!!" in your question, so that's an entirely expected sort of answer around here. There are fairly good pictorial and behavior resources on distinguishing Kahm yeast from mold on many fermentation information resources. Use them. From what I can see inthe picture, it's white to yellow white and only on the surface. That fits
    – Ecnerwal
    Dec 6, 2023 at 17:07
  • Likewise, on what seems to be the sharpest part of the picture when I zoom in, it appears smooth, not fuzzy (of course it's obviously corrugated itself as it's grown, but I don't see fuzz.) I'm unfortunately familiar with it from sauerkraut, where it's a common annoyance if anything escapes the wights and floats to the top. It's notably not black or green or pink as well as not appearing in the picture to be fuzzy.
    – Ecnerwal
    Dec 6, 2023 at 17:15
  • I have had mold on kimchi which is patch like and tastes weird. This on the other hand is waaay different. I will check and verify from resources as you said that its kahm yeast (possibility is very high). And then move accordingly. Thanks for the clarification and suggestions. Appreciate it.
    – Freed
    Dec 7, 2023 at 18:27

Honestly, it doesn't look good. If there was ever an active acetic acid bacteria culture there (and I don't see signs of one) the mold has long since outcompeted it, eaten up the sugar, and possibly made it chemically inhospitable to bacterial life. You might be able to strain it, boil it to inactivate antibiotics, and add sugar for fermentation, but I would also genuinely worry about toxins (even heat-stable ones) left behind.

Apple juice isn't valuable enough to engage in heroics here.

  • Thank you. I had not thought about the extra toxins and stuff. I would upvote but I can't. Thank you once again. Appreciate your input.
    – Freed
    Dec 6, 2023 at 15:52

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