Cyanidin

Cyanidin is an anthocyanidin, a type of flavonoid pigment found in many plants. As the aglycone form of cyanidin-based anthocyanins, it contributes red to purple hues to flowers, fruits, and other plant tissues. Anthocyanidins are typically present in nature as glycosides, such as cyanidin-3-glucoside, which influence their solubility and stability.

Natural sources of cyanidin include red onions, red cabbage, strawberries, raspberries, blueberries, cherries, grapes, and purple corn. It is also found in various edible flowers and ornamental fruits. The concentration and form of cyanidin can vary with plant species, cultivar, ripeness, and growing conditions.

Chemically, cyanidin is a flavylium cation whose color is highly sensitive to pH. In acidic environments it tends to appear red, becoming purple as the pH approaches neutrality, and shifting toward blue at higher pH. In foods, cyanidin commonly exists as glycosides (for example, cyanidin-3-glucoside or cyanidin-3-rutinoside); glycosylation and acylation affect its stability, solubility, and pigment behavior during processing and storage.

Biosynthesis occurs via the plant phenylpropanoid pathway, proceeding through the flavonoid pathway to form anthocyanidins, which are subsequently glycosylated. In humans, cyanidin glycosides are absorbed and metabolized to various conjugates and undergo enterohepatic circulation and excretion.

Applications include its use as a natural food colorant (E163). Cyanidin and related anthocyanins are studied for antioxidant activity and potential health effects, but clinical evidence remains inconclusive. They are generally considered safe at typical dietary exposures.