4

We had broad beans last night (in a risotto - yum!)

I emptied the beans from their pod, blanched them, then removed the skins from the individual beans before putting them into the risotto.

I never got round to cleaning up the pan in which I had blanched the beans, and when I came into the kitchen this morning I discovered that the water in it was a brown-ish/orange-ish/bronze-ish colour (still entirely transparent, though). There was no colouring at all after I'd blanched the beans, and I didn't do anything to the pan in between - just left it on the hob.

Does anyone know what the colour is, and by what mechanism it appeared overnight?

2 Answers 2

2

Speculating - (colloidal) rust - from iron in the beans - via oxidation.

3
  • see jake's comment. Both possibilities seem plausible. Any test we could do to prove it one way or the other? Anything that would react distinctively with either oxidised iron, or tannins?
    – Brondahl
    Oct 14, 2016 at 11:56
  • Is there elemental/metallic iron in beans that you could oxidize (in which case there might be a market opportunity for stainless beans), or is this complete nonsense? Oct 14, 2016 at 15:19
  • Could also come from the water - clear water iron...
    – Ecnerwal
    Oct 16, 2016 at 21:45
2

no, definitely not rust from the iron content in the beans, the amount of iron in Broad Beans is far too small for that. It is more likely the tannins from the beans.

1
  • This seems plausible. Any test we could do to prove it one way or the other? Anything that would react distinctively with either rust or tannins?
    – Brondahl
    Oct 14, 2016 at 11:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.