Allura Red AC is a red azo dye that goes by several names, including FD&C Red 40. It is used as a food dye and has the E number E129. Allura Red AC is also known as FD&C Red 40 It is usually supplied as its red sodium salt, but can also be used as the calcium and potassium salts. These salts are soluble in water. In solution, its maximum absorbance lies at about 504 nm. Orange-red colour used in sweets, drinks and condiments, medications and cosmetics, A red synthetic azo dye introduced in the early eighties to replace Amaranth, E123, in the United States of America where E123 is prohibited E number: E129 (colors) Chemical formula: C18H14N2Na2O8S2 CAS Number: 25956-17-6