Lecithin-sodium caseinate self-assembled complexes as emulsifying agents in oil-in-water emulsion: Acidic medium approach

Surfactant-polyelectrolyte complexes (SPECs) based on lecithin and sodium caseinate were produced and the effects of such binding on the physical, chemical and emulsifying properties were evaluated and compared with the two ingredients in isolation. Negative, neutral, and positive charged SPECs were obtained. Zeta potential values and size distributions of the SPECs were dependent on the mass ratio between compounds. Electrostatic association decreased the polydispersity index in comparison with pure compounds solutions. Analysis of interfacial properties showed that solutions containing SPECs promoted a greater reduction of surface tension and interfacial tension with sunflower oil when compared with pure compounds solutions. Emulsions produced with SPECs in 10:1 lecithin:sodium caseinate ratio proved to be more stable than emulsions prepared with pure compounds. Thus, the complexation improved the emulsifying properties of lecithin and sodium caseinate establishing SPECs as potential natural emulsifiers.