My mother pickled a bunch of garlic recently and it turned blue soon after. She has had this happen once or twice before where some turned green, but this time all of them turned really blue.
I tried Googling it, but only found mentions of it being a chemical reaction (that much is obvious) and mostly just speculation as to the causes and prevention, but little discussion on the safety of blue/green garlic. There are a couple of of question here about cooked / old garlic and onions turning green, but they have the same information as the other pages.
The few mentions of safety that I can find only go so far as to say that “it’s safe”—we assumed as much when we didn’t die after eating some last time—but they do not give any sort of explanation or proof to that effect. Chemical reactions are by definition change, which means that something that was safe can become not so.
Does anyone know of any information as to the safety of blue/green garlic (particularly pickled) that expounds on “it’s safe”, perhaps with some sort of test or experiment?
Best Answer
Since it was pickled, I believe it was a reaction with the vinegar causing it to turn green. Harold McGee has a good article on the very issue. He also goes into some detail in another artical here. I have heard various factors that can affect it, like the presence of dissolved metals, and the age of the garlic prior to being canned. However, I don't have any other info on those...
I do believe it's safe, assuming no other signs of spoilage are there.