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Dec 8, 2008 04:29 AM

Why did my soup turn black?

I made lentil barley soup yesterday in an enamel on steel Le Creuset stockpot and it turned a most unappealing shade of black. Why?

The ingredients, added all at once and cooked for 90 mins, were lentils, barley, carrots, onion, leeks, garlic, herbes de Provence, Italian sausage, chicken stock, and salt.

The soup tastes fine but is visually unappealing, to say the least.

The black substance has now stained the pot and the usual suspects of baking soda and vinegar and Bartenders Friend didn't help.

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  1. I'd be scared of the pot! I can't think of anything in the soup that should cause this. The whole thing seems weird.

    Did you maybe clean it with something strange that left a residue?

    1. As Morganna said, that really IS weird! I'm interested because your soup recipe sounds eerily like the one I planned on making this week with the inclusion of chopped spinach... in just such a pot!

      Did you rinse the lentils before adding them to the pot? Sometimes just rinsing isn't enough, though. You have to sift through them with your hands to make sure there are no foreign bits of stone and such.

      5 Replies
      1. re: Gio

        It's never happened to me with spinach but I added some c ooked russian kale to a bean soup the other week and it turned a purplish black. Really awful looking. I've added regular kale to soup many times and never had anything but good results.

        1. re: Ellen

          Purplish black? Sounds like something to make on Halloween. Russian kale is also called Red Kale. I wonder if there's a pigment in the stalk or leaf which is released during the cooking process. I've cooked regular kale many times too with no color change. Did you eat it anyway?

          1. re: Gio

            Come to think of it, it may have been tuscan kale. I tossed the whole batch. I used a piece of country ham to season it that ended up overwhelming it. I tossed in previously cooked kale to "save" it but it didn't, and the icky black color just made it easier to toss it. Life is too short to eat mediocre food, including my own.

        2. re: Gio

          To answer everyone's thoughtful questions -

          I did rinse and sort the lentils and rinsed the barley as well.

          They were brown lentils.

          Before yesterday when I tried to get the stains out, all I'd ever used to clean the pot was Dawn dishwashing liquid.

          1. re: Velda Mae

            Do you think it was the lentils that produced/leeched the dark liquid?

        3. What color were your lentils?

          Stains on you pot are nothing to worry about unless it affects the flavor of other dishes you cook in the pot. Cook with it a few times and I'm sure the stain will go away or dissipate.

          1. Do you have hard water? I do and I have experienced the same thing. Certain ingredients react with the minerals in my water and create some unusual effects. The most spectacular was a fennel broth that I used to make risotto--I was too cheap to throw it out. It was an alarming shade of prussian green. Not something I'd serve to others, but it tasted good.

            I've noticed a similar, but less severe effect, with black beans, peaches and other fruit. If I think it's going to be a problem I try to use bottled water for the recipe.

            I have on pot that is discolored, but since it doesn't transfer to new dishes I ahven't worried about it.

            2 Replies
            1. re: dct

              No, my water is fine and I've made this soup several times before but have never experienced this odd coloration. I called Le Creuset and followed their instructions to simmer 1 part Tide with 3 parts water for 20 mins up to two times and the pot is now restored. Like your broth, the soup tastes fine but is really unattractive.

              1. re: Velda Mae

                Thanks for the cleaning tip--it's my Le Creuset that is discolored.

            2. Sounds like a sulfur reaction. All your sulfurous ingredients interacted with the enamel/metal.

              Is every single thing you added in your ingredient list in your OP?

              Read more here:

              I'd also call Creuset. Your pot may be inadequately enameled. You do mean enamel on cast iron, not steel, right? Sounds like the black is ferrous sulfate (cast iron + sulfur).

              5 Replies
              1. re: maria lorraine

                No, I mean enamel on steel. It's a stockpot. I also own LC enamel on cast iron pots and have never had a problem with them.

                Yes, I listed every ingredient in my OP.

                I also called Creuset who gave me instructions for cleaning but didn't seem concerned about the item.

                Turns out my sister made the same soup last week in the same pot and didn't have a problem. I've also made this soup many times before and have never had this problem.

                1. re: Velda Mae

                  I have two Le Creuset pots that were given to me by my SO's grandmother before she passed on. She had them for years, possibly 30+! One is tiny, just big enough to fit four eggs for hard cooking or to warm up a single serving of soup. The other is bigger, perhaps 2QT. She obviously used this one a lot more often, because while the tiny one looks like new, the bigger one is no longer shiny and white inside. It appears that most of the enamel has worn away. I've used it many times. It's still a great pot, but I'm finding that with everything I make, the interior gets more discoloured and scruffy looking. I'm concerned that we're exposing ourselves to something unhealthy that we shouldn't, now that the enamel's worn away. Should I be tossing this pot and investing in a new one, or is this like a cast iron skillet: the rougher it looks, the more seasoned it is? I cooked black beans in it once and it is now a shade akin to kidney beans inside the pot. Is it time to say goodbye to my beloved LC pot?

                  1. re: 1sweetpea

                    My advice is to call Le Creuset. Their customer service is outstanding, as is their product warranty.

                  2. re: Velda Mae

                    Ah, the LC enamel stockpot -- I know the one you mean.

                    I still think it's a sulfur reaction. Write Harold McGee at his website.
                    It'd be great to know the answer. Lots about sulfur reactions with vegetables
                    on the internet.

                    1. re: maria lorraine

                      We used to have the purest water in the world. Chemicals have changed this for ever. This photo is of a brand new aluminum pot (bought yesterday!) and was used only to boil filtered tap water for tea. Not only did it stain the pot black where the water touched it, but the water turned very dark and has an unpleasant taste. It also causes dryness of the mouth. I will investigate further tomorrow, as pure water is not only healthy, it is essential for quality taste in food and beverages.