This review paper focused on the effect of typical phosphorlipid (or lecithin) and enzyme modification on electrokinetic parameters of oil/water emulsion. Physicochemical properties of the systems were investigated taking into account the effective diameter of the droplets as well as the zeta potentials using the dynamic light scattering technique. The effect of phospholipid and phospholipase modification on interfacial properties of o/w emulsion was examined as a function of temperature, pH and ionic strength (effect of Na+ or Ca2+ ions which occur in the physiological fluids). The particular role of Ca2+ ions in the dispersions with zwitterionic phospholipids (the main components of biological membrane) was confirmed.
The phospholipids dipalmitoylphosphatidylcholine, DPPC or dioleoylphosphatidylcholine, DOPC having the same headgroup bound to the apolar tail composed of two saturated or unsaturated chains were used as stabilizing agents. The effective diameters do not always correlate with the zeta potentials. A possible reason for such behaviour might a mechanism different from the electrostatic stabilization. Phospholipids and their mixtures (e.g. lecithin) may undergo spontaneous aggregation in aqueous solution and organize into liposomes, which possess different sizes and surface affinities. These unique behaviours of phospholipid dispersion can be controlled using the investigated parameters. These findings are expected to increase in importance as phospholipid systems see more use in self-assembly applications.
The other aim of the paper was the comparison of the enzyme phospholipase influence on lipid hydrolysis in the o/w emulsion environment. The work is the study which presents the twofold effect of ethanol dipoles on phosholipid hydrolysis. It is believed that the enzyme effect on the phospholipid aggregation behaviour at the oil-water interface will be helpful for understanding different biological phenomena.