Effect of chitosan structure modification and complexation to whey protein isolate on oil/water interface stabilization

Polyelectrolyte complexes (PECs) of biopolymers have been used for many applications, including emulsion stabilization and improvements in the properties of biopolymers, such as interfacial tension. The enhance of interfacial activity of biocompatible compounds is essential to the development of new natural stabilizers. Thus, the aim of this study was to understand how modifications on chitosan structure affect the interfacial tension of PECs. Positive, neutral and negative PECs were formed by varying chitosan or chitosan oligomers: whey protein isolate (WPI) mass ratios. Hydrolysis reduced chitosan size and increased zeta potential. FT-IR, 1H NMR analyses and crystallinity index confirmed structure modification. Chitosan oligomers showed lower crystallinity index and higher deacetylation degree than native chitosan. Positive chitosan PEC showed the lowest interfacial tension, suggesting a strong adsorption at interface oil–water and better interfacial stabilization than other PECs. Therefore, changes on chitosan structures enhance PECs interfacial properties and its use as emulsion stabilizer.