Freeze-thaw stability and rheological properties of high internal phase emulsions stabilized by phosphorylated perilla protein isolate: Effect of tea saponin concentration

This study investigated the interfacial behavior of phosphorylated perilla protein isolate (LZPI) and tea saponin (TS) as co-stabilizers in high internal phase emulsions (HIPEs), and its relationship with rheological properties and freeze-thaw stability of HIPEs was further explored. The results demonstrated that the interfacial adsorption process of LZPI-TS complexes could be divided into two stages. At low concentration (0.2–1.0%, w/v), TS had synergistic effects with LZPI, and the oil-water interface was dominated by LZPI co-adsorbing TS molecules. The combination of interfacial interaction and the improvement of interfacial film strength endowed the prepared HIPEs with enhanced performance, such as decreased droplet size, strengthened inter-droplet network structure, better viscoelasticity and structure-recovery property. However, at high TS concentration (1.5–2.0%, w/v), the interfacial film was mainly dominated by TS, and some LZPI would be replaced by TS from the interface into the aqueous phase, resulting in the reduction of interfacial film strength, further reducing the droplet size and viscoelasticity of HIPEs, but effectively improving the freeze-thaw stability of the system owing to the increased viscosity of the continuous phase and the decreased amount of ice crystals formed during the freezing process. These findings confirmed that the interfacial behavior of LZPI-TS complexes was regulated by TS concentration, which was closely related to the performance and stability of HIPEs. This study had important guiding significance for revealing the interaction between protein and small molecular emulsifier, and providing technical reference for developing mayonnaise-like emulsions with good performance and excellent freeze-thaw stability.