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In the image above, the dark green rings are ferrous sulfide rings, caused when the sulfur from the egg white reacts with the iron in the egg yolk when the egg is overcooked.

I was wondering, given the same circumstances, why do we not see our scrambled/fried eggs coated with this layer of ferrous sulfide?

  • $\begingroup$ I'm voting to close this question as off-topic because it is Food Science and not Biology in terms of SE Biology. $\endgroup$
    – David
    Apr 15, 2019 at 13:21
  • $\begingroup$ Although I htink David's concerns are valid, I disagree with him as our cooking stack doesn't typically attract these types of food science questions that are more focused on science vs food, and it certainly doesn't typically provide an answer that would adequately address the OP's science-leaning question. This question is probably most on topic either here or at Chemistry SE. $\endgroup$ Apr 15, 2019 at 17:54
  • $\begingroup$ @QuIcKmAtHs, I recommend that you do a bit of research on your own and indicate that you've done so more explicitly here. In doing so, you should be able to convince us that this is in fact a biology-related question (regarding biochemistry) and not simply a chemistry question. $\endgroup$ Apr 15, 2019 at 17:55
  • $\begingroup$ It would seem obvious, at least in part. 1) Proper scrambled and fried eggs are not overcooked, and it's a lot easier to determine when they are properly cooked when they're not in the shell. 2) Scrambled eggs are just that - scrambled - so even if ferrous sulfide did form, it would be mixed in rather than forming a visible ring - though I admit I have vague memories of greenish scrambled eggs from boot camp :-( $\endgroup$
    – jamesqf
    Apr 16, 2019 at 1:46
  • $\begingroup$ @theforestecologist thank you for your comments, I will take note of them. $\endgroup$
    – QuIcKmAtHs
    Apr 16, 2019 at 14:08

1 Answer 1


Scrambled eggs can change color, but you perhaps haven't run into a batch that shows discoloration. It is the same chemical reaction:

Why Scrambled Eggs Turn Green

When serving a large group, a buffet can provide enough food for everyone without the need to spend all of your time in the kitchen. Breakfast is a fairly simple buffet to set up, but there are special challenges when it comes to scrambled eggs. When scrambled eggs sit for a while, they tend to turn green or gray. This is a chemical reaction that happens as hydrogen sulfide in the egg white reacts with the iron in the yolk to form iron sulfide.

Via: https://living.thebump.com/lemon-juice-keep-raw-eggs-turning-green-cook-them-8383.html


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