Influence of charged polysaccharides and zein nanoparticles on the interfacial and emulsification properties of Pickering emulsions

Abstract

The stability of Pickering emulsions can be significantly improved through the synergistic interactions between colloidal particles and zein nanoparticles (ZNP). Moreover, the engagement of various charged polysaccharides (PS) with these particles at the interface can lead to the formation of distinct interfacial film structures, potentially affecting emulsion stability. Nonetheless, the current understanding of how the charge of polysaccharides influences the development and characteristics of these co-stabilized Pickering emulsions remains limited. This study explores the impact of ZNP in combination with different polysaccharides—cationic (chitosan), non-ionic (locust bean gum), and anionic (pectin)—on the interfacial and overall stability of Pickering emulsions. Initially, complexes of PS/ZNP were synthesized, and their crystalline structures and morphologies were analyzed. Subsequently, Pickering emulsions stabilized by these PS/ZNP complexes were prepared, and their emulsification characteristics, internal structures, and behavior at oil/water interfaces were examined. Variations in interfacial structure and wettability were assessed using confocal laser scanning microscopy (CLSM), along with contact angle and surface tension measurements. The cationic PS ZNP exhibited notable synergistic effects by substantially decreasing both interfacial and surface tension—key parameters for emulsion formation and stabilization. CLSM imaging indicated that the charge of the emulsifier influenced the interfacial structure of Pickering emulsions. In the absence of ZNP, Pickering emulsions stabilized only with PS showed large, unevenly distributed droplets. The inclusion of ZNP improved the contact angle values, enhancing the adsorption of PS at the oil-water interface and proving to be an effective stabilizer for Pickering emulsions. C-ZNP emerged as the most efficient surfactant, achieving the lowest surface tension of 37.02 mN/m. These findings could have important implications for optimizing the functionality of Pickering emulsions.