Extending the stability of red and blue colors of malvidin-3-glucoside-lipophilic derivatives in the presence of SDS micelles

Abstract

Anthocyanins lipophilization recently emerged as an efficient tool to deliver oil-soluble dyes aiming to expand their applications in lipophilic matrices such as cosmetics formulations. Sodium dodecyl sulfate (SDS) micelles were used to solubilize malvidin-3-glucoside derivatives bearing an ester chain derived from dodecanoic and hexanoic fatty acids. Detailed investigations on the kinetic and thermodynamic behavior of the pigments towards pH variations was carried out by means of UV-Vis spectroscopy. It was found that the pH domain of the red flavylium cation is extended in ca 0.3–0.4 pH units. The mole fraction of the quinoidal base at neutral conditions increased by 40% when compared with malvidin-3-glucoside in the same micellar media, which provides a great blue color stabilization. The results presented herein report for the first time the blue color stabilization of these lipophilic anthocyanin bioactives, opening new application fields as novel colorants for lipid-based foods and cosmetics.