Alfred Giger

Chemical synthesis project. A new yellow carotenoid

Naturally occurring colorants have been used in food processing for centuries to give meals an appealing color. In the first half of the 20th century, the newly discovered brilliant azo dyes, amongst other artificial colorants (indol, triphenylmethane, and methine dyes), were used as pigments for food coloration. The toxicity and/or allergenic potential of some of these colorants were discovered much later. One of these pigments with a critical safety profile is the azo dye tartrazine, which exhibits a nicely fresh greenish-yellow color. The use of tartrazine is now banned in several countries and restricted in others due to its unfavorable safety profile. With the aim of extending the color fan of nature-identical food colorants offered by Roche and therefore offering a less critical colorant to the food industry, a project was initiated at Roche. The goal was to find a safer, naturally occurring pigment with a color hue similar to tartrazine. This paper discusses the process of how such a project is addressed in industry, as well as how promising candidates were selected from the wide variety of the naturally occurring carotenoids. The syntheses of some of these carotenoids will also be described.