Annatto is a colored pigment extracted from the Central and South American plant Bixa orellana.
The color comes from the resinous outer covering of the seeds of the plant, and is composed of the carotenoid pigments bixin and norbixin, and their esters.
The central portion of those molecules is the same as that of the molecule ?-carotene, and the yellow orange color of annatto comes from the same physical chemistry origins as the orange color of ?-carotene.
Annatto is used in foods to provide color in cheese, butter, margarine, and microwave popcorn. It is often used as a substitute for the expensive herb saffron. It also has anti-oxidant properties.
The seeds are also used as a flavoring in the form of a powder or a paste, but the main use is as a coloring agent.
Because annatto binds well to the proteins in dairy foods, it is often used to add color to milk products such as butter, cheese, or puddings.