Synergistic effect of egg white protein particle and rhamnolipid on improving bioavailability of curcumin carried in high internal phase emulsions

Summary High internal phase emulsions (HIPEs) are potential carrier of fat-soluble nutrients due to their high loading capacity. This study, egg white protein particle (EWPP) and rhamnolipid (Rha) were used to co-emulsify oil/water HIPEs to carry curcumin (Cur). The results showed that, the Cur loading efficiency, microstructure, protein composition, molecular distribution of protein hydrolysates, protein interfacial adsorption rate and Cur bioavailability were measured. The results showed that, incorporation with Rha was unhelpful for improving loading efficiency of Cur, which decreased from 80.8% to 73.7% at pH 3.8 after incorporation with Rha, due to the decreased viscosity and destroyed continuous interface membrane, while beneficial for restricting coalescence of oil droplets. As studied, Rha could effectively reduce droplet size to slow down the speed of coalescence and form EWPP-Rha complex to inhibit proteolysis. Finally, Cur bioavailability in EWPP-Rha co-emulsified HIPE was the highest (40.3%), indicating the synergistic effect of EWPP and Rha promoting the effective adsorption of Cur, related to the increased coalescence stability during digestion and participation of Rha in the micellization reaction. In comparison, fibrous (pH 3.8) and granular (pH 7.0) EWPP stabilized HIPEs, showed no obvious difference in Cur bioavailability, due to the balance between interfacial adsorption ability and digestion resistance of EWPP with various morphology. This study has important significance for the construction of lipid soluble nutrient “carriers” with high load and high bioavailability.