Optical properties and structural coloration of chocolate

Chocolate consists of cocoa butter, cocoa particles, sugar, and additives, which together determine its taste and optical properties. The optical properties of chocolate play a vital role in consumer perception, representing type and quality in the blink of an eye. Here, we present a comprehensive analysis of the optical properties of white, milk, and dark chocolate, while demonstrating how to craft orange to blue chocolate via a thin food-grade coating. Using Mie theory, we show that chocolate can be treated as a turbid solid, where cocoa butter acts as a glass-like dielectric while all other ingredients contribute to its scattering and absorption. We expect the proposed coating to be easily adapted to other food surfaces to bring color to a broader range of edible products.