Blue garlic

[gbhunter]

I put garlic into homemade tomato soup base..just to see what it would taste like. It was really good :-) But, when i removed my cheesecloth containging the garlic..it was blue! Is this normal, has anyone ever had this happen before?

[Pete]

Sometimes this occurs when garlic is cooked with an acid. According to some things I have read, isoallin, a compound found in garlic, is broken down by acid then reacts with amino acids and turns a blue-green. I find that this doesn't affect the flavor, but it can look really strange. It has also been my experience that this happens more often with older garlic.

[Chef Rob]

More on the subject........looked into the reason pickled garlic sometimes turns blue. Garlic contains anthocyanins, water-soluble pigments that turn blue 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.

garlic contains sulfur compounds which can react with copper to form copper sulfate, a blue or blue-green compound. The amount of copper needed for this reaction is very small and is frequently found in normal water supplies. Raw garlic contains an enzyme that if not inactivated by heating reacts with sulfur (in the garlic) and copper (from water or utensils) to form blue copper sulfate. The garlic is still safe to eat.

Garlic exposed to direct sunlight can also turn green and acquire a bitter taste.