Yeah—that’s a red flag. If bubbles start rising immediately after opening canned tomatoes, that almost always means spoilage, not safe fermentation.
Here’s how to think about it:
What those bubbles mean
- Commercial canned tomatoes are heat-processed to be sterile
- They should not be actively producing gas
- Immediate bubbling = microbes created gas inside the can
Even if it is technically “fermentation,” in canned goods that’s still unsafe. You can’t tell which organism caused it, and some dangerous ones don’t smell bad or look scary.
Don’t rely on smell or taste
- Spoiled canned food can smell normal
- Never taste to check—just opening is enough info
Toss it if you notice:
- Bubbling or fizzing on opening
- Foamy liquid
- Sour, alcoholic, or “off” smell
- Bulging or leaking can (even before opening)
What to do now
- Do not eat it
- Pour it out carefully, avoid splashing
- Wash hands and any surfaces it touched
- When in doubt with canned food: throw it out
Annoying, I know—but you 100% did the right thing noticing it. If you want, tell me:
- canned whole / diced / crushed?
- brand?
- how long it’d been opened or stored?
Sometimes I can help pinpoint why it happened—but safety-wise, this one’s a definite discard.
