Interfacial properties and structure of Pickering emulsions co-stabilized by different charge emulsifiers and zein nanoparticles

The stability of Pickering emulsions can be improved by the synergistic action of colloidal particles and small molecule emulsifiers. In addition, the interaction between particles and different charge emulsifiers at the interface may result in different interfacial film structures, thus affecting the stability of Pickering emulsions. However, little is currently known about the impact of emulsifier charge on the fabrication and characteristics of these co-stabilized Pickering emulsions. Herein, we investigated the influence of Pickering emulsions co-stabilized by zein nanoparticles and anionic (quillaja saponin, QS), non-ionic (Tween 80), or cationic (lauroyl arginate ethyl hydrochloride) emulsifiers on the interfacial properties. The adsorption kinetics and rheological behavior of the molecular emulsifiers at oil/water interfaces were studied. Changes in interfacial structure and adsorption behavior were studied by confocal laser scanning microscopy (CLSM), and quartz crystal microbalance-dissipation (QCM-D) analysis. The dynamic interface characteristics showed that QS has good emulsification performance. The CLSM images indicated that the emulsifier charge impacted the interfacial structure of the Pickering emulsions. The combination of QS and zein nanoparticles formed a coating at the oil/water interface that was denser than for the other two emulsifiers, which improved the stability of the Pickering emulsions. QCM-D revealed that the interfacial film formed by anionic emulsifiers and zein nanoparticles was the thickest (about 6.6 nm). Moreover, anionic emulsifiers and zein nanoparticles stabilized Pickering emulsions provided the best protection against curcumin. These results may be important for optimizing the performance of Pickering emulsions in the food and pharmaceutical industries.