Safety of Blue / Green Garlic 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?
The answer is anthocyanins, the same that can turn ginger blue and are responsible for purple snap beans and cabbage. The reaction occurs relative to pH and is perfectly safe. Anthocyanins are present in their range of colors in many foods including cabbage, ginger, garlic, and berries. When used as an additive, they have the E number E163.