Flavonoids as Natural Pigments

The flavonoid family comprises the most widely distributed group of secondary plant metabolites consumed by humans, and are responsible for, or contribute to, the color of many foods. The color of flavonoid pigments ranges from white-cream to orange-red and purple-blue. Anthocyanins represent the most common group of natural flavonoid colorants on the market, being responsible for most of the orange-red to purple-blue colors in nature. In this chapter, an overview about the chemical structure of flavonoids, their biosynthesis, and applications is given. Important mechanisms which induce color loss of anthocyanins through chemical rearrangement are discussed and strategies for color stabilization are explained. Furthermore, also yellow flavonoid pigments, tannins, and pyroanthocyanins are discussed as important representatives. This chapter closes with a discussion of legal regulations which determine usage of flavonoids as food additive.