Natural betalains supported on γ-alumina: A wide family of stable pigments

• Gamma-alumina matrices with different textural and structural properties were prepared.
• The adsorption of betalains onto alumina surfaces leads to obtain of hybrid pigments.
• Stability and colours of pigments depends greatly of interactions alumina-chromophore.
• Purple stable pigments are obtained when chromophore stabilises inside alumina pores.

Natural betalain chromophores, extracted from bougainvillea flowers, were stabilised on different surfaces of γ-alumina matrices. This strategy was used to produce a family of hybrid pigments including one yellow and several purple hues. Both textural and structural parameters of γ-alumina were identified as important factors to stabilise the chromophores. Particularly, a high amount of coordinative unsaturated sites of aluminium, high surface specific areas and pore diameters as high as 15 nm are suitable to stabilise the purple chromophores.

Extracting colour as dyes from flowers and transfer it onto alumina to obtain stable pigments.Figure optionsDownload as PowerPoint slide