Annatto, also called Roucou, is a natural plant extract used to dye an assortment of foods, textiles, and body care products. Primarily, it is used as red food coloring in a wide assortment of foods. The food additive number for annatto is E160b, allowing consumers to identify it on a label even when it is not listed by name. Two compounds give annatto its unique red color: bixin, and norbixin. The compounds are very similar chemically to beta-carotene, the substance which makes carrots red.

The achiote tree, botanically known as Bixa orellana, provides the source for annatto. It prefers loamy soil in tropical conditions at low elevations, and can range in height from almost shrub-like to a full grown tree. Achiote has heart shaped green leaves and rose-pink to white five petaled flowers. When the tree fruits, the pulp around the fruit can be processed to make annatto, and the seeds are preserved for use in cooking. The trees have been used in food for centuries by Latin Americans, and their products were introduced to Europe by early explorers in the 1500s.

An alternate name for achiote seeds is the “poor man's saffron,” because they are often used to color foods. The seeds are steeped in hot water to extract the characteristic red color, or they are fried in oil to color the oil. The flavor of the seeds is slightly sweet and also peppery, with a touch of nutmeg. The seeds are known by a plethora of native names, including atsuwete in the Philippines, where the plant was imported by the Spanish, and urucum.

The red annatto dye extracted from the pulp is used in an assortment of industries. Another alternate name for the achiote tree is the “lipstick tree,” a nod to the use of annatto in cosmetics. Annatto is also used to dye textiles. However, the largest use of annatto is as a food coloring. Annatto appears in preserved meats, cheeses, sweets, and numerous other foods. It is safe for vegetarians, since it contains no animal products and is not processed with animal materials, and is also approved for religious diets.

Food dyes can sometimes cause allergic reactions. It can be difficult to pin down the source of the reaction, since so many dyes are added to processed foods. Children seem to be especially susceptible to additives like annatto. If allergic reactions cannot be linked with common allergens like wheat, dairy, or nuts, testing for sensitivity to food dyes may be a good idea.