Effect of pH, ionic strength, chitosan deacetylation on the stability and rheological properties of O/W emulsions formulated with chitosan/casein complexes

Abstract

Emulsions stabilized by polysaccharide/protein complexes have attracted great interest. However, their emulsion properties and interfacial viscoelastic behavior need to be further investigated. Here, emulsion stabilized by chitosan/casein complexes was used as a model system and the effects of chitosan concentration, pH, ionic strength, and chitosan deacetylation degree on the rheological properties and stability of emulsion were studied. The presence of chitosan could effectively improve the emulsification activity of casein and the stability of the obtained emulsion. The emulsion stabilized by chitosan/casein complexes showed broad emulsification pH range from 3.5 to 6.5. The rheological properties of the chitosan/casein complexes were proved to be primarily affected by chitosan, showing great shear resistance, fast adsorption interface capability, and predominantly viscous characteristics. The loss modulus (G″) was much larger than the storage modulus (G′) in all the rheological tests, suggesting that the stability of the complexes stabilized emulsion mostly depended on the viscosity effects, rapid adsorption characteristics and spatial effects of biopolymer structures. These findings might help developing stable, controllable polysaccharide/protein emulsification systems.