Annatto is an orange-red food coloring or condiment made from the seeds of the achiote (Bixa Orellana), which grows in the tropics of South and Central America.
It has several other names, including achiote, achiotillo, bija, urucum, and atsuete.
It is most commonly used as a natural food coloring because it imparts a bright color ranging from yellow to dark orange red, similar to saffron and turmeric.
Its color comes from compounds called carotenoids, which are pigments found in the outer layer of the seed and in many other fruits and vegetables, such as carrots and tomatoes.
Use as an acidiﬁer in place of cheese cultures when making the quick version for Mozzarella cheese or to replace vinegar or lemon juice when making Ricotta.
It is used to acidify milk and cause the separation of solid elements (curdled milk) from liquid (whey). The dose depends on the cheese made.