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Anyone ever had garlic turn blue-green while cooking?

Kitty Mar 17, 2001 06:09 AM

This happened while I was sauteeing veal last night. I had garlic, veal, capers and artichokes in the pan, and immediately after I added a bit of white wine and lemon, the garlic turned bright blue-green! We ate it anyway and it tasted fine, so it couldn't have been harmful. (after cooking a while longer, the color started to fade a bit) I have never seen this happen in restaurants, and I am sure I have eaten dishes with the same ingredients. What went wrong?

  1. d
    Deven Black Mar 17, 2001 10:29 PM

    I've never seen what you describe, but I assume the garlic was reacting with something else in the pan or the pan itself. I do remember seeing a reaction like this a long time ago and if I had paid more attention to high school chemistry I might be able to give you an idea of what the reaction was. I guess the next step would be to try to recreate the effect. Try doing it with another clove from the same head to garlic. If it happens again try using a different head of garlic. If it doesn't happen with the second head at least you'll know it was the garlic. You could keep changing one item at a time (a different pan, different butter, etc.) until you find out which is the culprit. Happy experimenting!

    1 Reply
    1. re: Deven Black
      maria lorraine Aug 30, 2012 07:38 PM

      Why Does Garlic Turn Blue and Is Blue Garlic Safe To Eat?
      :The colors occur when enzymes and amino acids present in garlic react with the sulfur compounds responsible for garlic’s pungent smell. The reaction causes different multipyrrole molecules to form. Different types of multipyrrole molecules are responsible for the different pigments. The multipyrrole molecule most familiar to us is chlorophyll, produced by plants in the presence of light; however, chlorophyll is not produced by the cooking or pickling processes that turn garlic blue."

      My pickled garlic turned a pale greenish-blue color. What's wrong?
      "According to the Food Network at www.foodtv.com...they looked into the reason pickled garlic sometimes turns blue or green. Garlic contains anthocyanins, water-soluble pigments that turn blue, green or purple in an acid solution. While this color transformation tends to occur more often with immature garlic, it can differ among cloves within the same head of garlic. The garlic flavor remains unchanged, and it totally edible without bodily harm."

    2. a
      Anne H. Mar 18, 2001 11:56 AM

      This question is popping up all over the place lately. I would have guessed a reaction with the metal too, but this is not so.

      This is the most commonly asked garlic question at UC Davis extension

      "Why did my garlic turn blue?

      The answer is: Garlic contains anthocyanins, water-soluble pigments that can turn blue or purple under acidic conditions. This is a variable phenomenon that is more pronounced for immature garlic but can differ among cloves within a single head of garlic. If you grow your own garlic, be sure to mature it at room temperature for a couple of weeks before using it.

      Link: http://cetulare.ucdavis.edu/news/n089...

      3 Replies
      1. re: Anne H.
        Kitty Mar 18, 2001 05:55 PM

        Thanks so much for the info! It must have been the acidity caused by adding the lemon and wine.

        1. re: Anne H.
          rlculpepper Jun 15, 2009 10:07 AM

          I understand the science being cited, but I've been cooking with garlic in this way for a while and haven't noticed the garlic routinely turning blue until recently. I'm cooking in anodized aluminum which is new for me. Could the metal make a difference? Is bulk garlic being treated differently than before? (Irradiated)

          1. re: Anne H.
            maria lorraine Jun 22, 2010 01:06 AM

            That's not correct, sorry. It's not an acid-based (as in lemon juice) reaction.

            The reaction is due to a defense mechanism -- an enzyme -- that is released in the garlic when it is chopped. It reacts with sulfur compounds and amino acids in the garlic, and turns blue. The blue compound is isoalliin, and there is more potential for it in young garlic, the reason garlic bulbs are often stored for two weeks before going to market.

            Here's the scientific notation:
            "The discoloration is due to pigments that form between sulfur compounds in garlic and amino acids. When the garlic tissue is disrupted, as happens in processing, an enzyme is liberated and reacts with it to form thiosulfinates compounds that then react with the natural amino acids in the garlic to form blue pigments. The age of garlic determines how much isoalliin there is in the first place, and the nature of the processing determines how much enzyme is liberated."

            Identification of Two Novel Pigment Precursors and a Reddish-Purple Pigment Involved in the Blue-Green Discoloration of Onion and Garlic, Journal of Agricultural and Food Chemistry, 2006, 54 (3), pp 843–847 DOI: Publication Date (Web): January 12, 2006.

          2. c
            Caitlin Wheeler Mar 19, 2001 09:38 AM

            Anne H. is probably right, since she has scientific evidence to back up her claim, but I did notice after cooking artichokes the other day (plain, boiled with mayonnaise, no garlic) that the leaves turned blue green after a couple of days (I'm a lazy dishwasher) Maybe it's related?

            1 Reply
            1. re: Caitlin Wheeler
              kitchenhelper Sep 2, 2010 11:29 AM

              Two days of unwashed mayo and artichokes? No offense, but I think what you experienced is called "mold."

            2. l
              lgss Jun 16, 2009 04:42 AM

              I've had it happen, freaky at first sight, but fine. I've also have sunflower seeds in baked goods turn green.

              1. m
                moh Jun 16, 2009 04:58 AM

                My mum pickled some garlic in vinegar, and they turned blue green. The odd thing is, she has done this before and they have been fine, so I don't know why these ones turned blue green.

                1 Reply
                1. re: moh
                  Lance23 Aug 21, 2009 09:16 AM

                  Vinegar can contain trace amounts of copper from being distilled in copper vessels. The acid copper combination together with a sulfur compound in fresh garlic turns it green. Copper pots or even other pans with trace amounts of copper can produce the same result while cooking.

                2. l
                  lawgirl3278 Jun 16, 2009 07:41 AM

                  It's happened to me when I've added lemon to the garlic.

                  1 Reply
                  1. re: lawgirl3278
                    BamiaWruz Jun 20, 2010 01:34 PM

                    This always happens to me when I make an egyptian dish called Fattah and I sautee the garlic and add vinegar to it to top the rice. Turns blue, Looks unappetizing but tastes great.

                    Has to be the lemon.

                  2. l
                    Lance23 Aug 21, 2009 09:13 AM

                    Acidity releases sulfur naturally occurring in the garlic which combines with trace copper either from your pan or from your water or already present in the garlic, which forms copper sulfate a greenish blue compound. It is considered harmless in trace amounts involved in cooking. I have heard that this only happens with fresh picked garlic or bottled fresh refrigerated garlic. Fresh garlic aged a week or two is less likely to turn green.

                    3 Replies
                    1. re: Lance23
                      Cpt. Rawhide Jun 20, 2010 12:25 PM

                      Ahhh, it is great to get the answer to this strange phenomenon. I noticed this occurrence when I inserted whole garlic cloves into a pork roast and rubbed it with Dijon mustard. I thought that it might have been a chemical reaction with the garlic and the mustard, but it is interesting to know it can actually happen with anything acidic. I was bemused and amused by the colourful aquamarine addition to the presentation as you cannot usually find such a shade in the food found on Earth.

                      1. re: Cpt. Rawhide
                        wendymc Sep 2, 2010 02:56 PM

                        I had to google 'can lemons turn my garlic green' and this post came up with the search results. My recipe called for microwaving 2sliced lemons with some peeled garlic in a bowl. As the lemons heat up, the juice extracts and it turned my garlic blue-green! I just need to know now if it's still OK to eat. I guess I'll find out.

                        1. re: wendymc
                          lgss Sep 2, 2010 03:24 PM

                          Yes, it's ok to eat.

                    2. davinagr Aug 30, 2012 11:16 AM

                      I am making homemade dill kosher pickles and the same phenomenon is happening, I was trying to retrace my steps to see why this happened. I semi crushed the garlic with a metal knife, also used refrigerated garlic cloves that come in a container from my local market already peeled. The brine I'm using is just salt and herbs and spices. I'm wondering if it's the refrigeration as mentioned by other posters and the utencil used to smash the garlic maybe. I hate the way it looks; looks moldy-ish but glad to hear it's safe.

                      4 Replies
                      1. re: davinagr
                        Lance23 Aug 30, 2012 03:02 PM

                        the copper can be in a pan or in the vinegar itself if the vinegar was made in a copper kettle then the combination of copper vinegar (acid) and sulphur in the garlic makes the green color. the vinegar doesn't always contain copper and sometimes it may happen overnight or over a few days. If its raw like in a vinegarette you may not notice any change. Cooking it speeds up the process, refrigeration would slow it down a little but its chemistry. If all three sulphur acid and copper are present you get green stuff.

                        1. re: Lance23
                          maria lorraine Aug 30, 2012 03:38 PM

                          It's a natural sulfur reaction from the garlic. See my post of Jun 22, 2010 01:06 AM above.

                          1. re: Lance23
                            KaimukiMan Aug 30, 2012 08:06 PM

                            just like in a pool. it was never the chlorine that turned hair green. chlorine is a bleaching agent. what turned hair green was copper leached out of the pipes by high chlorine levels. now that most pool pipes are pvc green hair is very rare.

                            1. re: KaimukiMan
                              maria lorraine Aug 30, 2012 08:45 PM

                              Copper does not play a role. It might in other blue/verdigris reactions but isn't the cause of blue-green garlic

                              Here's the explanation from food scientist Harold McGee in the New York Times:

                              "I hear every year from cooks who have been alarmed at seeing normally pale garlic turn bright green and even blue, sometimes when the cloves are pickled whole, sometimes when they’re chopped and cooked with other ingredients. I was really rattled the first time I puréed raw garlic, onion and ginger together...[and] when I fried the purée the entire mass turned turquoise blue.

                              "According to chemists at the China Agricultural University in Beijing, aging the garlic gives it a chance to accumulate large quantities of one of the chemicals that generate the color; fresh garlic doesn’t green much at all. And a strong green color develops in Laba garlic only with acetic acid, the main acid in vinegar (also found in sourdough), because it’s especially effective at breaching internal membranes and mixing the cell chemicals that react together to create the green pigment. The pigment itself turns out to be a close chemical relative of chlorophyll, which gives all green leaves their color.

                              "Two recent reports from the House Foods Corporation in Japan detail exactly how the garlic and garlic-onion pigments develop. Their creators are the same handful of sulfur compounds and enzymes that give the allium family its unique pungent flavors. Under the right conditions these chemicals react with each other and with common amino acids to make pyrroles, clusters of carbon-nitrogen rings. These rings can be linked together into multipyrrole molecules.

                              "The ring structures absorb particular wavelengths of light, and thus appear colored. The two-pyrrole molecule looks red, the three-pyrrole molecule looks blue and the four-pyrrole molecule looks green, as does its cousin tetrapyrrole, the chlorophyll molecule. Like chlorophyll, all the pyrrole pigments are perfectly safe to eat.

                              "A mixture of onion and garlic favors a blue hue. All the pigments result from a combination of enzyme activity and simple chemical reactions, so you get the most intense color by puréeing the garlic and onion to mix enzymes thoroughly with their targets, then holding the purée on low heat to speed the enzymes without denaturing them, and finally heating it to a simmer to speed the nonenzymatic reactions."

                              Here's the link to the entire explanation in the New York Times:
                              "When Science Sniffs Around the Kitchen":

                              The part on garlic turning blue is just over halfway down in the NYT article.

                              Here's the link on Harold McGee's Curious Cook website:

                        2. RealMenJulienne Aug 30, 2012 12:33 PM

                          This has happened to me when I made roast chicken with a garlic-lemon-herb crust. My question is, why doesn't it happen in a vinaigrette?

                          1 Reply
                          1. re: RealMenJulienne
                            Lance23 Aug 30, 2012 03:03 PM

                            Se my above reply :-)

                          2. k
                            kseiverd Aug 30, 2012 04:53 PM

                            Happened to me a while back when I was doing some green bean pickles. Blanched green beans, thing sliced onions and red bell peppers packed into jars. The brine... kinda bread& butter. The smashed agrlic cloves turned almost a NEON color in the hot brine?? Was assured but somebody/somewhere that it would have no effect on flavor... and wouldn't kill me!?!

                            1 Reply
                            1. re: kseiverd
                              bearfromobx Aug 30, 2012 05:07 PM

                              Neon Dilly Beans - Way too cool for words...

                            2. b
                              bearfromobx Aug 30, 2012 06:05 PM

                              I'm prone to agree with the copper reaction as well; the blue green color isn't produced by many chemical reactions without some level of copper involved and sulfur in garlic loves to react in an acidic envornment. The first thought that comes to mind is the color of a copper roof as it weathers.

                              1. TrishUntrapped Aug 30, 2012 07:52 PM

                                As others have said, garlic does not seem to turn blue from the acid. I make lemon garlic chicken cutlets all the time on the stovetop (chicken dipped in flour, egg, and breadcrumbs, lemon, butter, garlic, chicken stock, parsley). In fact it's my signature dish. Most times the garlic stays white but I'd say one in 15 times the garlic turns bluish/green.

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