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Sep 16, 2006 08:53 AM

Why did my blend of raw ginger, garlic & onion turn aqua?

Freaky. I tossed some white onion, yellow onion, garlic cloves and fresh ginger in the blender for a butter paneer masala recipe. I had a little too much, so I put the uncooked portion in the fridge, and shazam! it turned sort of aqua-y in color. It's not old enough to be mold, so I'm gussing that there is some nifty chemistry thing going on. Anyone have a good guess?

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  1. I reckon it could be the bleach in the garlic, we made preserved lemon holding liquid and had whole cloves of garlic with a bit of white skin on them.. after sitting there for a while a wierd bluish colour came from the garlic cloves..???maybe !! ????

    2 Replies
    1. re: pinktori71

      Thanks! I've been a little weirded out, so I'm glad someone has had a similar experience. Anyone else?
      By the way, how did your lemons turn out and what do you like to use them in?

      1. re: Bananna A.

        Lemons turn out good.. nice in cous cous, and sometimes as a garnish.

    2. Remember in high school chemistry class those little strips that were used to test pH level, they turned different colours? Those strips are made using anthocyanins, water-based pigments that naturally occur in the plant world. Anthocyanins change colour according to the pH level of a solution (base = green/yellow, neutral = blue/purple, acidic = red). Anthocyanins in garlic appear on the base end of the scale because the vegetable is low acid.

      Probably what happened here is that the sulfur compounds released by the onions mixed with water released by the ginger (or did you add some water?) to create a weak sulfuric acid (the same reaction that makes us cry when cutting onions). The sulfuric acid changed the pH level in the mixture causing a reaction that turned the anthocyanin in the garlic blue. The change occurs on a molecular level, altering light absorption and reflection, similar to the way leaves change colour in the fall.

      It is harmless to eat.

      1. Two possibilities:

        Garlic contains a compound that turns blue under acidic conditions (vinegar, wine, lemon juice. I wonder if ginger is acidic enough?

        Chopped garlic can turn blue under non-acidic conditions if the sulfur compounds in the garlic react with copper to form copper sulfate, which is blue. I think there is also a possibility that other metals (iron, aluminum) might react with different color results(?) It only takes a trace of metal... tap water

        Bottom line is that if either of these things happen, your garlic mixture is still safe to eat and there should not be any taste change.


        1 Reply
        1. re: PamelaD

          This is so interesting! I just ate garlic bread I cooked, with the following ingredients: lemon juice, salt, pepper, garlic and butter. It was wrapped in aluminium foil also, and turned greenish blue...made me think exactly of copper sulfate from a science experiment at high school, and also of the copper patina on metal (I am a ceramic artist, so have some chemistry interest and knowledge), so my guess was that copper was involved somewhere along the line. Yay science!

        2. I've actually seen a blueish-aqua tint to ginger, just under the skin.

          Never had anything like this happen with garlic. Good to know so I won't faint dead away if it happens in future.

          1. Thanks, folks!
            I will not fear, but embrace the bluish mix, though it continues to be a rather unappetizing color after I add the tumeric and tomatoes for the masala.

            Hmmm, wonder if it would look funny in soup?