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Kayak8's avatar

Calling all Chemists . . . what the Hell happened? (details inside)

Asked by Kayak8 (16395 points ) August 2nd, 2011

I made a salad that included boiling water and vinegar and sugar and pouring it over cucumbers, garlic, and onions (not too complicated). I put it in the fridge overnight and then put some in Tupperware for my lunch the next day. I am sitting at work, eating my lunch and open the container—the garlic has turned blue. I mean really blue (aquamarine to be exact). What was the chemical reaction that made the garlic blue?

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19 Answers

josie's avatar

I know the following. Garlic contains lots of sulfer. Sulfer will combine with copper to form copper sulfate which is aquamarine. Some cooking utensils or pots and pans that are copper will do that. Doesn’t sound like your problem, though. Not sure. Are you sure it was garlic and not some alien product like in Invasion of the Body Snatchers?

Jeruba's avatar

Can we see a picture?

flo's avatar

I’m not a chemist but I have heard of it from chemists explaining that it is nothing to worry about. I don’t know this site but maybe it has something? http://www.apinchof.com/garlicqanda.htm
In the first paragraph it says ”Under acidic conditions, isoallin, a compound found in garlic, breaks down and reacts with amino acids to produce a blue-green color.” Again I don’t know how reliable the site is.

flo's avatar

….Additional info: ”...fresh garlic cloves sometimes take on an odd blue-green shade when cooked with acid (tomatoes, in this case). Under acidic conditions, isoallin, a compound…

ETpro's avatar

My first thought was copper sulphate too, just as @josie suggests. But the question is what supplied the copper. There is nothing in your list that’s usually a rich source of elemental copper.

syz's avatar

“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.”

Source

Kayak8's avatar

Wow, we figured out I used fresh garlic and now we figured out that it was immature . . . @Jeruba I pitched it before thinking to photograph it. I will be making the salad again soon (wait a sec, there is still some in the fridge, let me see if more garlic changed color). BRB

Kayak8's avatar

OK, I have strained the stuff still in the primary bowl from the fridge, found two pieces (neither is quite as blue as the two in my lunch but you will get the idea), then took photo, then uploaded photo to computer, then forgot my photobucket password and had the link to reset it emailed to me, then logged in, then uploaded photo and here it is (I hope).

Jeruba's avatar

That’s great, @Kayak8. Now how about a longer shot that shows us these particles in context, with the salad as a complementary setting? I want to get the full aesthetic effect.

Wow, anthocyanins, as in cyan—blue. Lovely word.

Kayak8's avatar

@Jeruba Only for you here is the contextual picture for aesthetic effect! No, I will not portion it onto a silver platter or depict the poor little blue garlic in any other way!

Jeruba's avatar

Thank you, @Kayak8, I love it!

flo's avatar

There are results in Google Here but why is it did you mean “iso + sulpher”?
And, http://www.chemistry-dictionary.com/search-results.php?w=isoallin doesn’‘t recognize it?

flo's avatar

…And Wikipedia doesn’t recognize it. So what does that mean? It doesn’t exist?
http://en.wikipedia.org/w/index.php?title=Special%3ASearch&search=isoallin

Jeruba's avatar

Because “sulpher” is a misspelling.

flo's avatar

@Jeruba oops! Thanks for the correction. I have to get back to this next time.

flo's avatar

But isn’t Google’s “Did you mean…” meant to correct the spellings?

Kayak8's avatar

@flo so what I am witnessing is basically what I would call the “hydrangea effect,” same principle?

flo's avatar

@Kayak8 I have no idea what the answer to that is. I don’t see anything about garlic and blue in the Anthocyanin page, by the way, do you? I entered those key words and I got that, I was in a hurry when I posted it so I didn’t read too much of it. The other thing is if Google can give me sites that refer to the word Isoallin, why does it not recognize it’s existance? Anyway I posted a question about it.

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