Adsorption and rheological properties of biopolymers at the air‐water interface

Abstract Dynamics of adsorption and viscoelasticity of biopolymers (β‐lactoglobulin (β‐lg) + polysaccharides (PS)) at 20 °C and pH 7 have been studied. Protein concentration in the bulk phase was 0.1 wt %, and the concentration of polysaccharides (xanthan gum, λ‐carrageenan, and propylenglicol alginate with different degrees of esterification and viscosity) was varied from 0.1% to 0.5 wt %. The results reveal a significant effect of surface‐active and non surface‐active polysaccharides on the dynamics of the formation and viscoelasticity of adsorbed films at the air‐water interface. The rate of diffusion of the biopolymers increased in the mixed systems, but the effect was more significant at the highest concentration of polysaccharide (0.5 wt %). The rate of rearrangement of the adsorbed films decreased in the presence of polysaccharides as compared to the protein film. Competitive adsorption, complexation and limited thermodynamic incompatibility between β‐lactoglobulin and polysaccharide would explain the observed effects. © 2006 American Institute of Chemical Engineers AIChE J, 2006