Anthocyanins (also anthocyans; from Greek anthos “flower” and kyaneos/kyanous “dark blue”) are a group of biological pigments. They are soluble in water and alcohols and insoluble in apolar organic solvents. Anthocyanins may appear red, purple or blue depending on the pH and they are among natural pigments used as colorants. Anthocyanins are mostly found in flowers and fruits but they can also be present in leaves, stems and roots.
Many plants are rich in anthocyanins and many flowers and fruits owe their color to anthocyanins. Roughly 2% of all hydrocarbons fixed in photosynthesis are converted into flavonoids and their derivatives such as anthocyanins. Seed coat of black soybean approximately contains 2 g per 100 g, the highest recorded amount. Anyway, they are also many plants with very low or even without any anthocyanin content. Among plants rich in anthocyanins are blueberry, cranberry, bilberry, black berry, black raspberry, red raspberry, blackcurrant, cherry, eggplant peel, black rice, Okinawan sweet potato, concord grape, muscadine grape, red cabbage and viola.
Anthocyanins are plant pigments of the flavonoid class where flavonoids are natural products derived from flavone. Anthocyanins are formed from anthocyanidins by addition of sugars (very often glucose) to them where anthocyanidins are oxygenated derivatives of flavylium salts.
Examples include: Pelargonidin, an anthocyanidin with a characteristic orange color used in food and industrial dyes; Callistephin, an anthocyanin formed from pelargonidin and glucose, it is found in pomegranate juice, strawberries, purple corn, and also berry skins of Cabernet Sauvignon and Pinot Noir grapes.