Formulation and characterization of oil/water emulsions stabilized by biopolymer complexes

Abstract

   

Emulsions are thermodynamically unstable colloidal systems consisting of two immiscible liquids. To overcome the use of potentially irritating synthetic surfactants, this study evaluates the stabilization of simple oil/water emulsions using natural biopolymers, specifically proteins and polysaccharides. Emulsions were formulated using olive oil and mixtures of chitosan, starch, and mycological peptone. The influence of pH (2, 3, and 4) on the formation of biopolymer complexes was investigated. Macroscopic and microscopic characterizations revealed that the emulsion stabilized by the chitosan/protein complex at pH 4 exhibited the best physical stability. This stability was manifested by the absence of phase separation, sedimentation, and coalescence. UV-Visible spectrophotometry analyses showed a maximum absorbance at this pH, indicating maximal interaction between the macromolecules. Finally, infrared spectroscopy confirmed the formation of physical interactions between the protein and the polysaccharide, leading to a perfectly homogeneous phase. The chitosan/protein emulsion at pH 4 demonstrated superior stability, maintaining a homogeneous structure without phase separation, unlike the unstable chitosan/starch emulsions. FTIR analysis revealed strong interactions between chitosan and protein, evidenced by changes in the O–H, C–H, and C=O bands, whereas the unstable emulsions showed no significant spectral changes, indicating a lack of intermolecular interactions.