Is there a temperature range on which onions turn into the black color with bitter taste? Excuse me if this can be found elsewhere on internet, but I am not sure where to look.

1 Answer 1


Time matters. Onions have a lot of water in them; as that boils off they caramelize and then move to burning as they dry out more, while being held at one temperature. Thus, there's no single "temperature at which they burn."

  • 4
    There's also whether you keep them turning or wander off & forget ;)
    – Tetsujin
    Commented Oct 1, 2023 at 14:03
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    It sounds like you're talking about a pan temperature where they burn, because dryer onions are able to heat up closer to the pan temperature, farther above the boiling point of water. Or does loss of water actually affect the temperature at which chemical reactions can take place inside a cell of onion plant matter? (Knowing what temperature the actual onions cells can safely reach would be interesting but not directly helpful, since in cooking it'll be insulated by a layer of vaporizing water, and you need higher pan temperatures to make things happen in reasonable time, right?) Commented Oct 2, 2023 at 5:59
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    Presumably liquid water would keep the internal temperature under 100°C. Burning would only happen above that temperature.
    – bdsl
    Commented Oct 2, 2023 at 8:21
  • I'm sure there is a specific (or rather a range) of temperatures where onions burn just like anything else. It's just not useful. What you need to know is what they look like when they are done to your liking.
    – JimmyJames
    Commented Oct 2, 2023 at 20:17
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    @Tetsujin - That's always been my downfall with cookery, making something really nice and then ruining it at the last minute by leaving it on the heat as I go off and do something else
    – Richard
    Commented Oct 2, 2023 at 22:34

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