Edible Amorphous Structural Color

Due to the scarcity of blue color in the natural food palette, synthetic blue edible colorants are commonly used in daily life. With growing awareness of environmental hazards and potential side‐effect impacts of synthetic food colorants on customers’ health, synthetic blue edible colorants are no longer a good choice. Here, a strategy of mixing two edible sub‐microspheres, mesoporous hollow TiO2 sub‐microspheres or SiO2 sub‐microspheres and cuttlefish ink particles, is reported to produce mass amorphous photonic structures (APSs) with structural color. The hues can be tuned by controlling the size of mesoporous hollow TiO2 sub‐microspheres, and the saturation is strongly related to the proportion of cuttlefish ink particles. Cytotoxicity assays and evaluation of bioaccessibility in the simulated human digestive system further prove the safety of the blue structural colorants. The blue structural colorants exhibit high color visibility, thermostability, and reliable food safety, which are promising properties for food, drugs, and cosmetics. An edible structural blue colorant (applied on a cream cake in the image) is proposed and demonstrated by mixing cuttlefish ink nanoparticles and hollow TiO2 sub‐microspheres or SiO2 sub‐microspheres. The schematic diagram shows the coherent scattering of light in the amorphous photonic structure.