Food coloring is the obvious answer.
Natural pigments are widely used in the food industry and have been studied extensively. Long before the art of food coloring, however, was the natural coloring of plants which surround us. Betalains are an example. DOPA-dioxygenase is the key enzyme involved in betalain biosynthesis. It converts 3,4-dihydroxyphenylalanine to betalamic acid, a yellow chromophore.