Microalgae have three main pigments: chlorophyll that absorbs blue light; red carotenoids that absorb blue and green light; and phycobilins that absorb green, yellow, and orange light. These pigments have been used as natural colorants in food products. In many countries biodyes have replaced artificial dyes, which are currently prohibited.

p-carotene is a carotenoid found in all higher plants and algae. p-carotene acts as pro­vitamin A and may be used as a natural food color. Phycolibins are water-soluble pigments and are found only in red algae or cyanobacterias. Most members of cyanophyceae contain blue pigment (phycocyanin), although several species may also contain erythrin. Phycoery- thrin and phycocyanin can be used as natural pigments in food, medicine, and cosmetics, avoiding the use of artificial pigments that are carcinogenic (Richmond, 1990).