A comprehensive study of physical, antimicrobial and emulsifying properties of self-assembled chitosan/lecithin complexes produced in aqueous media

Demand for products containing natural compounds has grown in recent decades and synthetic emulsifiers probably will be replaced. Lecithin is a natural emulsifier, but it has low emulsifying capacity for stabilizing oil-in water emulsions and does not show antimicrobial property. Thus, we proposed the development of surfactant-polyelectrolyte complexes (SPECs) based on lecithin (Lip) and chitosan (Chi) in order to provide antimicrobial properties and to enhance the emulsifying properties of lecithin. The physicochemical properties of SPECs were depending on the mass ratios between compounds. SPECs showed sizes ranging from 1.5 to 5.5 microns and Zeta potential values ranging from −49.5 mV to +38.5 mV. All SPECs showed surfactant properties reducing superficial tension and interfacial tension with sunflower oil. SPECs with positive Zeta potentials values and at concentration of 2.5 mg/mL were able to inhibit the Escherichia coli growth. Through droplet size measurements, may be observed that emulsions prepared with SPECs showed coalescence decreasing when compared with those prepared only with lecithin or chitosan. These results showed that SPECs can be modulated in their physicochemical properties to be potential emulsifiers with antimicrobial properties.