I have some bread that should still be good for few days that now smells like vinegar. There is no mold, ect. on it that makes it look bad. It is store bought whole grain bread with some oatmeal, if that matters.

Personally, I've never known bread to smell like vinegar, even when it has gone bad. So what would cause it?

  • Did it smell like vinegar when it was just opened? Or did it develop the smell over time?
    – Jolenealaska
    Commented Aug 27, 2014 at 19:09
  • It just developed the smell over the last 2 days. Before that it didn't have the smell. Commented Aug 27, 2014 at 19:25

3 Answers 3


I also emailed KAF my question. They think ferment time is culprit. I will have to give it a try.

Could it also maybe be combo of time + yeast? Bread is still tasty; I am still experimenting.


Here is reply from KAF:

Hello Stephen,

Thank you for contacting us here at King Arthur Flour.

The vinegar-ish smell you describe is from the acids of your fermented dough. If it bothers you, you might try fermenting your dough in a slightly cooler room, or for a shorter time. This should help.

Please let us know if we can be of further assistance or if you have additional questions. If you need immediate assistance, feel free to contact us directly at 800-827-6836.

Thank you again and have a great day!



King Arthur Flour 800-827-6836


Vinegar is acetic acid. It is made when yeast eat starch and produce alcohol which is then consumed by acetobacter bacteria to make acetic acid.

I have a hard time imagining a bread smelling strongly of vinegar but all the ingredients are there. The bread was fermented by yeast and did contain alcohol before it was baked. If the bread was a little underbaked and picked up the right bacteria it could be trace amounts of vinegar.

Other options are that the bread picked up a normal sourdough-esque bacteria and just smells sour without having actual acetic acid.
Either of these options would require the bread to be under baked or very moist.

Anything beyond this would be conjecture.
Maybe the bread was baked with vinegar in it?

  • The bread is very moist. It almost seems more moist now than when I last used it two days ago, though that may just be memory bias. Commented Aug 27, 2014 at 19:26
  • 1
    Regarding the moisture, I have had the same thing happen a few times. Each time it was store bought bread that had gotten drier after keeping it a few days and then it changed and got pretty moist. I never have really tried to figure it out but, it didn't smell like vinegar, it just had a somewhat yeasty smell.
    – Cindy
    Commented Aug 27, 2014 at 20:05
  • I have seen some breads use vinegar as an ingredient - used as a "preservative".
    – GeezerGeek
    Commented Aug 29, 2014 at 17:25
  • If I leave store bought bread out in my kitchen during the summer it eventually gets wet on the bottom. I left a piece of this out a little longer to see what happened, and it started to rot not too long after. Not bread mold, but actual (bacterial?) rot with a smell a bit similar to rotting vegetable matter.
    – Air
    Commented Aug 29, 2014 at 22:42

I'd like to suggest that over-proofed bread produces a very yeasty smell, like the smell of half fermented beer. Easily mistaken for vinegar.

Then a low- less than normal - baking time for this might well produce the smell you are describing. At a relatively fresh state, the bread scent overpowers the residual from the beer brewery.

Source: I fell asleep during the last proofing one time. My kitchen smelled like I was in a beer brewery

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