Bixin is a natural carotenoid pigment extracted from the seeds of the annatto tree (Bixa orellana). It is the primary coloring agent in annatto, widely used as a food additive (E160b) to impart orange-red hues to dairy products, oils, and processed foods. As a lipophilic compound, it exhibits antioxidant properties and is stable in fats but sensitive to light and oxidation. Bixin is the monomethyl ester of the dicarboxylic acid norbixin, which is formed upon alkaline hydrolysis. Its conjugated polyene structure is responsible for its vibrant color and biological activity.