Formation of oil-in-water emulsions from natural emulsifiers using spontaneous emulsification: sunflower phospholipids.

This study examined the possibility of producing oil-in-water emulsions using a natural surfactant (sunflower phospholipids) and a low-energy method (spontaneous emulsification). Spontaneous emulsification was carried out by titrating an organic phase (oil and phospholipid) into an aqueous phase with continuous stirring. The influence of phospholipid composition, surfactant-to-oil ratio (SOR), initial phospholipids location, storage time, phospholipid type, and preparation method was tested. The initial droplet size depended on the nature of the phospholipid used, which was attributed to differences in phospholipid composition. Droplet size decreased with increasing SOR and was smallest when the phospholipid was fully dissolved in the organic phase rather than the aqueous phase. The droplets formed using spontaneous emulsification were relatively large (d > 10 μm), and so the emulsions were unstable to gravitational separation. At low SORs (0.1 and 0.5), emulsions produced with phospholipids had a smaller particle diameter than those produced with a synthetic surfactant (Tween 80), but at a higher SOR (1.0), this trend was reversed. High-energy methods (microfluidization and sonication) formed significantly smaller droplets (d < 10 μm) than spontaneous emulsification. The results from this study show that low-energy methods could be utilized with natural surfactants for applications for which fine droplets are not essential.