Particle coating is one of the oldest pharmaceutical processes that is still in existence. It is the process of applying a thin polymer-based film to a particle or granule containing the active pharmaceutical ingredient. The widely used methods for particle coating are sugar coating, film coating, and enteric coating and the techniques are pan coating, fluidized bed coating, and compression coating. Sugar coating was the earlier coating method, and it was gradually replaced by film coating because it required skilled manipulation. With the technology developing, enteric coating draws more attention. Pan coating is the most classic coating technique, which is applied to sugar coating, film coating and enteric coating. Fluid bed coating is used for a mixture of multiple materials and medicines and keeps the bioavailability high. Compression coating can avoid the harmful effects of moisture and high temperature, while it requires highly accurate machinery.

Titania is a white pigment used widely in papermaking, paints and cosmetic industries. Dispersion and stabilization of high concentration titania in water-based system remains a great bottleneck in industry nowadays, because aggregation of titania nanoparticles results in severe adverse effects to gloss, opacity, tint strength, color distribution and storage stability of end products. Because kappa-carrageenan (κ-CG) has excellent rheological properties such as emulsification, gelation, stability and so on, it has the ability to form gel and increase the viscosity of aqueous solution. In this work, Octenyl succinic anhydride (OSA) starch was utilized as wall material to encapsulate titania pigments using electrostatic spray drying processing. Transmission electron microscopy (TEM) showed that titania pigments were coated by OSA starch, with a final form of nanoparticle. Accelerating stability test found that around 60% OSA starch–titania particles were stably dispersed in κ-CG-based solution. All materials used in this work were natural ingredient, which would be preferred by cosmetic industry and consumers. The technique used in the present study could potentially be extended to other pigments for similar purpose.