Composite emulsifying behavior of egg white protein and rhamnolipid: Properties of the constructed high internal phase emulsions

Abstract This study investigated the interaction between egg white protein particles (EWPP) and rhamnolipid (Rha) as co-emulsifiers in high internal phase emulsions (HIPEs). To reveal the effect between EWPP and Rha on the properties of HIPEs, the physicochemical properties (particle size, zeta-potential and microstructure) and emulsifying capacity were investigated. The results showed that, with the increase in Rha content, the EWPP-Rha complex could be divided into three regions according to the emulsifying capacity. The emulsion properties at different regions were analyzed by microstructure, rheology and nuclear magnetic resonance etc. The addition of Rha may compete interface with EWPP, adjusting the properties of constructed HIPEs. Generally, the replacement of EWPP by Rha from interface decreased emulsion droplets and disrupted the inter-droplet network, resulting to the formation of soft and flexible emulsions. The incorporation with Rha was beneficial for improving the emulsifying capacity of EWPP. In Rha sufficient system, more EWPP distributed in the aqueous phase of constructed HIPEs and functioned as a stabilizer to increase coalescence stability. The study was meaningful for revealing the complicated relation between protein particle and surfactant, and improving properties of high internal phase emulsions combining the advantages of each emulsifier.