ADSORBED FILMS OF BETA-LACTOGLOBULIN + LECITHIN AT THE HYDROCARBON WATER AND TRIGLYCERIDE WATER INTERFACES

The influence of lecithin (egg yolk phosphatidylcholine) on the properties of adsorbed films of beta-lactoglobulin at the surface of emulsion droplets and at macroscopic oil-water interfaces is investigated at pH 7. The amount of protein adsorbed during formation of oil-in-water emulsions (20% wt oil, 0.4% wt protein) is substantially lower with soya oil as the dispersed phase than with n-tetradecane. Limited protein displacement from the emulsion droplet surface occurs at high values of the lecithin:protein molar ratio. Time dependent surface shear viscosities of adsorbed films of beta-lactoglobulin are lower at the triglyceride-water interface than at the hydrocarbon-water interface. The presence of lecithin at a molar ratio of 100 leads to a reduction in measured surface viscosity of the aged film by about an order of magnitude.