The stability of natural anthocyanin toward alkaline environment and visible light irradiation was greatly enhanced by intercalation into montmorillonite.
The enhancement of the stability was brought about both by the electrostatic interaction between the intercalated dye and the montmorillonite surface and by the protection of the intercalated dye from atmospheric oxygen.
The intercalated and stabilized anthocyanin can be a candidate of an environmentally friendly coloring material.