Cooking Garlic the "Wrong" Way Can Make It Turn BlueEsther Inglis-Arkell8/18/15 9:30am437EditPromoteGo to permalinkPeople who cook garlic have sometimes been alarmed to see their garlic turn green, blue, or turquoise as it cooked. What the hell happened? Bacterial infestation? Poison added by assassins? Actually, it was just chemistry.