I grew tomatoes this year and then made sauce out of them about 3 weeks ago (tomatoes, onion, garlic, basil, olive oil, salt). When I opened the jar I heard the distinct sound of C02 releasing. I looked in the jar and saw a good amount of bubbling. No visible mold in the jar. It doesn't smell bad, just fermented.

I've made a variety of pickled and fermented foods before and never had a problem eating those. Kimchi comes to mind as a similar food where the fermentation comes without adding any starters, just salt, cabbage, and spices. For some reason the fact that i didn't intend to ferment the sauce is making me second guess eating it. Is it possible to use salt/vinegar to kill off any bad bacteria lingering in the sauce? What if I were to convert the sauce into a fermented ketchup?

  • Can you give us some additional details? What did you do with the sauce after you put it in jars? Was it refrigerated? When you made the sauce, how did you prepare it - was it canned, for example? This sounds really dangerous, but I'm not an expert, so I strongly encourage you to wait to eat anything until you get an answer here.
    – Catija
    Commented Sep 1, 2017 at 22:14
  • It's not fermented, it's spoiled.
    – SnakeDoc
    Commented Sep 1, 2017 at 22:21
  • 2
    Sounds like a great way to get botulism. Please, please don't eat this. No amount of cooking can remove the toxins that are possibly present here.
    – Catija
    Commented Sep 1, 2017 at 23:30
  • 1
    I generally agree with not eating this, but it's incorrect to say that the toxins can't be neutralized. Botulism toxin (specifically) actually can be neutralized by cooking. "Though spores of C. botulinum are heat-resistant, the toxin produced by bacteria growing out of the spores under anaerobic conditions is destroyed by boiling (for example, at internal temperature greater than 85 °C for 5 minutes or longer)." [who.int/mediacentre/factsheets/fs270/en ]
    – Ecnerwal
    Commented Sep 2, 2017 at 2:39
  • 1
    The fact that that it was "improperly canned" but then refrigerated also cuts against botulism, which is otherwise a great bet (onions and garlic are very likely to have spores.) Botulism is supposed to be effectively inactive below 38F. so if it's been under refrigeration since it was made, something's going on, but it's probably not botulism.
    – Ecnerwal
    Commented Sep 2, 2017 at 2:48

2 Answers 2


Do. Not. Eat.

The assumption that it fermented enough to be safe because it fermented some is likely incorrect. Lacto fermented food recipes are specifically formulated to encourage the rapid and significant growth of lactic acid producing bacteria which lowers the ph so quickly that it overwhelms pathogens which are also trying to grow. Even then, consuming lacto fermented vegetables before they hit a ph level of 4.6 is still not safe. Almost no tomato sauces would be acidic enough to discourage pathogen growth on their own.

Even if the lactic acid in the sauce slowly built up enough to kill all of the live pathogens with acid alone, many food pathogens create toxins (Shiga, Botulism Toxin, etc,) and those could still harm or kill you, even if you heated the sauce up to serving temperature. Though botulism toxin can be neutralized by boiling for some amount of time, after looking around for a bit, I haven't seen anything that guarantees Shiga or other common toxins do too. Is it worth it?

There are lots of pathogens which thrive in that very environment, and plenty that produce gas as waste. You don't know what was growing in there, or what it left behind.


Y'all are overthinking WAAAAAAAAAY TOO MUCH, this product probably won't be pleasant for much other than kimchee, however it absolutely will not hurt you, the acidic value alone is not an environment for ANY bacteria

  • That's just my take on it, I'm a bartender and we ferment all kinds of things in AND out of the refrigerator for weeks at a time.... look at Kamboocha Tea, how is it made...
    – Peejat
    Commented Mar 19, 2019 at 22:23
  • There's a big difference between controlled and accidental fermentation as ChefAndy explains. Fermentation recipes are set up to quickly induce the growth of the desired bacteria. If fermentation happens accidentally, who knows which bacteria have grown. Commented Mar 20, 2019 at 8:23

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