When cooking fresh cranberry shell beans, is there a way to set the color so that they don't turn from lovely rose to unappetizing gray?
Alas, no. Heat breaks down the pigment. Maybe it'll help if you think of the cooked beans as Borlottis.
Nope - it's what they do! But they sure taste wonderful.
Actually, I discovered a "kind of" answer when I recalled that Julia Child advised adding a shot of red wine vinegar to red cabbage for the same reason, to help set the color. So I did that and the beans came out much pinker, kind of a dusty rose. I have an enormous crop of these beans, so am still curious if anyone else has an opinion.
I mispoke when I said the heat broke down the pigment--cooking breaks the sort-of sacs that hold the red pigments, and they dissolve into the water.
Acid does tend to keep red pigments red and it works well with cabbage. The problem I see with using it for cranberry beans is that acid (the vinegar) strengthens cell walls, and adding it during cooking could make the beans permanently tough. A lot of people do the opposite of adding acid (they add baking soda) to help beans cook. mainecook, did you add your shot of vinegar at the end? I can imagine that would help restore a little color but not a heck of a lot, because most of the pigment is completely gone. Come to think of it, I make lots of cranberry beans with oil and vinegar, and I've never noticed any return to rosiness. Fun topic. If I had yours big crop, I'd set up a few experiments.
Maybe I will run a bean lab.
That tablespoon of red wine vinegar didn't make them tough at all. Perhaps being just picked helped there. They were lovely (went into a colorful succotash).