Sourdough Starter Smells Like Acetone

Sourdough starter can smell like acetone because of overactive wild yeast. Luckily, the acetone smell of your starter can be easily fixed in just a few days. So definitely don’t throw out your starter!

New starters can often develop an acetone smell when they are less than two weeks old. The wild yeast that exists naturally in wheat is expanding and reproducing as it tries to establish itself and may overdevelop which creates a chemical reaction that produces the acetone smell. Over time, as your starter matures, the acetone smell will naturally go away. Just keep feeding your starter and you should be good in a few days!

Mature starters can develop an acetone smell as well if they are too wet or too hungry. If you are using a high-hydration starter recipe, the very wet starter may have an excess of liquid which causes the wild yeast to overdevelop and cause the acetone smell.

Another reason mature starters create an acetone smell is that they are hungry and underfed, triggering another chemical process that produces the acetone smell. Giving your starter a regular daily feeding will correct the acetone smell within three to five days.

A sourdough starter that smells like acetone may also be reacting to warmer temperatures. A kitchen (or wherever you keep your sourdough starter) that is warmer than 77°F or 25°C will cause the wild yeast to eat quicker and become hungry sooner. This is another example of an underfed starter creating an unpleasant acetone smell because it needs more food. If you cannot adjust the temperature of where your starter lives, consider feeding it more often (twice a day instead of once for example).

Can I use my sourdough starter if it smells like acetone?

A sourdough starter that smells like acetone usually means that the starter is hungry and needs to be fed. Therefore, you should not use the starter if it smells like acetone because the underfed starter will not raise your bread adequately and you will be left with a flat loaf. It will be perfectly fine to eat, but not as delicious as a well-risen loaf.

Flat sourdough

Can I use a sourdough discard that smells like acetone?

You can use the sourdough discard that smells like acetone, especially for things like pancakes and waffles where you are less concerned with how much they will rise. However, I wouldn’t use it for sourdough pizza as you do want a nice rise from that dough to give you those tasty air bubbles. The smell of the acetone will dissipate through the cooking process.

You make pancakes with sourdough discard even if it smells like nail polish remover. It’s because the smell is caused by lactic acid that is produced when bacteria break down natural sugars. The smell will not be present in your pancakes, but you can reduce it by keeping the discard in the refrigerator. Pancakes made with sourdough discard are a great way to make use of something that would otherwise go to waste!

If you’re baking a loaf of sourdough bread you are expecting a significant rise in the crumb created by the starter emitting gas, and a sourdough starter that smells like acetone is likely underfed and will give you the desired result.

Sourdough starter smells like nail polish remover

Sourdough starter can smell like nail polish remover due to overactive wild yeast that is naturally present in the flour. It doesn’t matter what type of flour you are using, all types of wild yeast can produce this smell in a young, overly wet, or underfed sourdough starter. However, all of these problems in your starter can be fixed so definitely do not discard it.

A young starter that smells like nail polish remover simply needs to be fed twice a day for its first two weeks and the smell will naturally go away. Easy peasy!

Overly wet sourdough starters may have some separated water form on the top which will smell like nail polish remover. Simply skim as much of the water off the top as possible and consider adding 10-20% more flour to your daily feedings until the nail polish remover smell is gone.

An underfed sourdough starter can also smell like nail polish remover and the fix is easy: feed it! A properly fed starter that isn’t overly wet will not smell like nail polish remover.

Why does my sourdough starter smell like paint?

A sourdough starter that smells like paint is most often due to overactive wild yeast and can be easily remedied. Just like for sourdough starter that smells like acetone or nail polish remover, a starter that smells like paint is common in very young starters (less than 2 weeks old) that haven’t fully established themselves yet. Simply keep feeding your young starter for another week or two twice a day and the smell of paint will go away.

If you are using a high-hydration sourdough starter recipe you may end up with a starter that has too much water content in it. This makes the sourdough starter out of balance between water and flour and the yeast will be underfed. Simply adapting your starter recipe by adding a bit more flour will address the imbalance and your sourdough starter will stop smelling like paint within a few days.

Wondering what else your sourdough starter can smell like? Check out my master list of sourdough starter smells.

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