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Feb 28, 2013 09:05 AM

Changed color

On Saturday, I made purple mashed potatoes, see pc. They have a distinct purple color when fresh. However, when I went to put leftovers in my lunch this morning, they were very blue. This is the second time I've refrigerated leftovers and had a color change. The first time, I didn't really make a note of it, but now it's got me wondering... Why do purple mashed potatoes turn blue when you refrigerate them?

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  1. It's probably something to do with anthocyanins. We know they are heat-sensitive (cooked red cabbage or onions turn blue unless acid is added). Try adding a little wine or vinegar
    next time you make purple mash and see what happens with the leftovers.

    1. oxidation.
      At least they stay purple through cooking. Purple string beans, sadly, turn green when cooked.
      Anyone know if this is true for purple cauliflower?

      In addition to acid, if they were held in an airtight environment they might stay more purple. You could cover them in a layer of fat like pate or confit.

      5 Replies
      1. re: splatgirl

        I read online that white mashed will turn gray due to oxidation.. was wondering if that was the case. Blue is nice, but I love the color of the fresh purplr mash and the blue was intense.

        I, too, was disappointed when my purple string beans turned green.

        1. re: splatgirl

          Purple cauliflower turns green if boiled, but not if roasted.

          1. re: sr44

            Not all purple cauliflower turns green when boiled. There are several varieties out these days that remain purple after boiling or steaming. Really outstanding in appearance when combined with white & the orange "cheddar" varieties.

          2. re: splatgirl

            "Anyone know if this is true for purple cauliflower?"

            It depends on the variety. There are several out now that remain purple after cooking.