Anthocyanin is a water-soluble pigment,it can follow the concentration of cell sap pH to change the color.The Anthocyanin pigment widely present in purple sweet potato, grapes, blood orange, red cabbage, blueberries, eggplant skin, cherry, red-orange, cranberries, strawberries, mulberry, hawthorn bark, basil, black (red) meter, petunia and other plants.