If there's a tiny bit of mold on nearly-finished maple syrup (like, a tiny patch in a pot of 1.5 gal), and it's removed and the syrup is brought back to a boil, is there any particular pathogen that would make it unsafe to bottle? Wikipedia says botulism toxin "is destroyed by heating to more than 85 °C (185 °F) for greater than 5 minutes." But is there any other information I'm missing?

I'm fully expecting a lot of "better safe than sorry" comments. Short answer to that is, "yeah I know."

  • 2
    Well, given that many commercial maple syrup bottles come with a note to just remove any "harmless" surface mold, I would guess that you're probably OK, but that's just a guess.
    – Marti
    Commented Apr 3, 2014 at 15:44

1 Answer 1


Not many molds can live in a substance with such a low water activity. They call those things "xerophiles": they're the food equivalent of those bacteria that grow in cyanide and lava and crap like that...Foodie extremophiles.

These are probably some kind of wallemiomycetes. I can't find any information on whether or not they're toxic, but, generally if you have any kind of mold infestation, it will affect the taste.

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