Erythrosine, also known as Red No. 3, is an organoiodine compound, specifically a derivative of fluorone. It is a pink dye that is primarily used for food coloring. Erythrosine is commonly used in sweets such as some candies and popsicles, and even more widely used in cake-decorating gels. It is also used to color pistachio shells. As a food additive, it has the E number E127 E number: E127 (colours) Chemical formula: C20H6I4Na2O5 CAS Number: 16423-68-0 Molar mass: 879.86 g/mol