Curcumin (/ˈkərkjuːmən/, diferuloylmethane) is a bright yellow chemical produced by some plants. It is the principal curcuminoid of turmeric (Curcuma longa), a member of the ginger family (Zingiberaceae). It is sold as an herbal supplement, cosmetics ingredient, food flavoring and food coloring. As a food additive, its E number is E100. Chemically, curcumin is a diarylheptanoid, belonging to the group of curcuminoids, which are natural phenols responsible for turmeric's' yellow color. It is a tautomeric compound existing in enolic form in organic solvents and as a keto form in water.