Protection of anthocyanin-rich extract from pH-induced color changes using water-in-oil-in-water emulsions

Abstract

The food, cosmetics, and personal care industries are increasingly interested in replacing synthetic colorants with natural alternatives. Anthocyanin is a renewable and sustainable source of plant-derived pigment. However, their application in commercial products is often limited because of their susceptibility to chemical degradation, which leads to color fading and/or a change in hue. In this study, we examined the possibility of protecting anthocyanin from degradation by encapsulating them within the inner water phase of a water-in-oil-in-water (W/O/W) emulsion. Polyglycerol polyricinoleate (PGPR) was used as a hydrophobic emulsifier, while quillaja saponin was used as a hydrophilic emulsifier. First, W/O emulsions containing 20% aqueous phase and 80% oil phase (PGPR in corn oil) were prepared using a microfluidizer. Second, W/O/W emulsions were prepared by blending 20% W/O emulsion with 80% aqueous phase (saponin in water) using a high-shear mixer. Changes in color, particle size, charge, and anthocyanin leakage of the emulsions were measured when the external aqueous phase was changed from pH 7 to 3. Anthocyanin encapsulation significantly slowed down pH-induced color changes, possibly because the internal aqueous phase had a different pH to the external one. Anthocyanin transfer between aqueous phases depended on pH, temperature, and initial location. Our results suggest that multiple emulsions may be useful for encapsulation and protection of natural colors.