Anthocyanins are plant pigments that can be found in blue, dark-blue, purple, and red vegetables and fruits. They are present in eggplant skin, blackberries, blueberries, raspberries, black currants, grapes, cherries, oranges, red onions, red cabbage, and so on. The color of the anthocyanins depends on the acidity of their surroundings; they turn red in an acidic medium, blue in an alkali medium, and purple in a neutral environment.