Last updated: June 10, 2026.
Yes, sauerkraut can go bad, even though it is fermented. A sour smell, tangy flavor, and some bubbles can be normal, but visible mold, rotten odor, unusual slime, leaking packaging, or unsafe storage history means the safest choice is to discard it.
Normal Fermentation Or Spoilage?
| What you notice | Usually normal? | What to do |
|---|---|---|
| Tangy sour smell | Often yes | Expected in fermented cabbage |
| Some bubbles in active sauerkraut | Often yes | Can happen during fermentation |
| White surface film | Sometimes yeast, sometimes not | Use caution; discard if unsure or if mold appears |
| Fuzzy mold, colored growth, or black spots | No | Discard |
| Rotten smell, unusual slime, leaking jar | No | Discard |
How To Store Sauerkraut
- Follow the label for commercial sauerkraut.
- Refrigerate opened jars unless the label gives different instructions.
- Use clean utensils to avoid introducing crumbs or bacteria.
- Keep sauerkraut covered with brine when the product is meant to stay submerged.
- Do not eat from jars with leaking, swollen, cracked, or badly damaged packaging.
Homemade Sauerkraut Needs More Caution
Homemade sauerkraut should be made with a tested fermentation method, the right salt level, clean equipment, and proper storage. If the batch develops mold, putrid odor, unusual colors, or signs that the cabbage was not safely fermented, discard it.
When To Throw Sauerkraut Away
- Visible mold or fuzzy growth
- Rotten, sewage-like, or strongly unpleasant odor
- Unusual slime or texture change beyond normal fermentation
- Jar leaks, spurts, cracks, bulges, or has a broken seal
- Unknown storage history after opening
- Any doubt with homemade sauerkraut made from an untested process
FAQ
Is fizzy sauerkraut bad?
Not always. Some fizz can be normal in active fermented sauerkraut. Discard it if fizz comes with mold, rotten odor, leaking packaging, or unsafe storage history.
Can you scrape mold off sauerkraut?
Do not rely on scraping mold off sauerkraut, especially from a retail jar or an uncertain homemade batch. Discard it when mold or fuzzy growth appears.
Does opened sauerkraut need refrigeration?
Most opened retail sauerkraut should be refrigerated unless the label gives different directions. Refrigeration slows quality loss and spoilage.
What does bad sauerkraut smell like?
Bad sauerkraut can smell rotten, putrid, or strongly unpleasant rather than cleanly sour. Do not taste it to check.