Anthocyanin refers to the pigment found in both red grapes and beets that gives them their red color. Anthocyanin is the same element that is responsible for most of the color in red, purple, and blue fruits and flowers. When foods containing Anthocyanin are combined with a substance that is too alkaline, the color will change from red to purple and begin to fade. Adding an acid will prevent this and will even reverse the effect after it has occurred, changing the purple color back to red.