Highly transparent antioxidant high internal phase emulsion gels stabilized solely by C-phycocyanin: Facilitated formation through subunit dissociation and refractive index matching

Abstract

In the work, we report a kind of novel highly transparent oil-in-water (O/W) HIPE gels stabilized solely by c -phycocyanin (CPC; an important biliprotein pigment), with a great potential to act as outstanding containers for heat or UV labile lipophilic bioactives. The CPC was solubilized in 6 M urea solution containing 40 wt% glycerol, in order to achieve the improved emulsification performance of the protein, as well as the transparency of the resultant HIPE gels through the refractive index (RI) matching between the aqueous and dispersed oil (dodacane) phases. Using 6 M urea containing 40 wt% glycerol as the aqueous phase, the transparent HIPE gels could be formed at the CPC concentration ( c ) as low as 0.1 wt%, and oil fractions in the range 0.6–0.86. In the protein-poor regime, e.g., c < 0.5 wt%, increasing the c led to a progressive decrease in emulsion size, as well as strengthening of gel network, while in the protein-rich regime ( c = 0.5–1.0 wt%), the emulsion droplet and gel stiffness were independent of the c . The as-fabricated transparent HIPEs (gels) exhibited an outstanding oxidative protection to encapsulated β -carotene against degradation upon extensive heating or UV irradiation. • A kind of novel transparent antioxidant HIPE gels stabilized by c -phycocyanin was reported. • The transparency of HIPE gels was achieved by a RI matching technique with urea and glycerol. • The emulsification performance of c -phycocyanin was remarkably improved by the presence of 6 M urea. • The chemical stability and antioxidant capacities of c-phycocyanin were unaffected by the usage of urea and glycerol. • The as-fabricated transparent HIPE gels exhibit a great potential in cosmetic and other formulations.