Why did my beans go black?

[Tricotrin]

Last night I cooked some broad beans in a cast iron pot with flour, butter, white wine and oregano. Throughout the process they gradually turned black, and they now look like they've been cooked in squid ink! I would really like to know what turned them black. I assume it's the cast iron pot, but what exactly is going on?

 

[Andy M.]

Welcome to DC, Tricotrin.

Most likely the white wine, an acidic ingredient, is the culprit here. I'd guess the beans didn't taste too good either.

 

[Tricotrin]

Thanks Andy. I didn't realise wine was acidic. (If I had I wouldn't have used it because we just bought the pot and were trying to keep acidic food off it for a while yet. I hope it hasn't taken too much of the seasoning off it.)

Suprisingly, the beans taste OK.

 

[mcnerd]

Anything acidic needs to be done in a non-reactive pan and in your case the cast iron pot probably reacted chemically with the food items.