Starter smells like acetone
Why a sourdough starter smells like acetone, nail polish remover, or sharp alcohol, and how to fix it without starting over.
If your sourdough starter smells like acetone, nail polish remover, or sharp alcohol, it is usually not ruined. It is probably hungry, too warm, underfed, or sitting with too much acid buildup.
what the acetone smell means
Acetone-like aroma is a stress signal. The starter has consumed available food and is producing sharper alcohol and acid compounds. It often happens after a long time between feedings, in a warm kitchen, or when the starter is kept at a very small feeding ratio.
quick fix
- Keep 10g starter and discard the rest.
- Feed 50g water and 50g flour. This is a 1:5:5 refresh.
- Keep it at 72-76°F if possible.
- Repeat once or twice until the smell turns pleasantly tangy, yeasty, or yogurt-like.
- Bake only once it doubles predictably. Then use the beginner sourdough boule recipe as a control bake.
how to prevent it
- Use a larger feeding ratio when the kitchen is warm.
- Do not keep too much old starter in the jar.
- Move the starter to the fridge if you bake less than twice a week.
- Use a clean jar every few feedings so dried acidic residue does not build up.
where to go next
If the starter smells fine but will not rise, read why won't my starter rise. If it rises but the loaf is heavy, go to dense sourdough loaf.
Crosodo Blog entries are recipe and craft notes from working cottage bakers. Recipes assume working with an active starter and basic equipment. Cottage food sales are governed by your state's law — see our state directory for legal details.