THE ROLE OF DIGLYCERIDES, MONOGLYCERIDES AND FREE FATTY-ACIDS IN OLIVE OIL MINOR SURFACE-ACTIVE LIPID INTERACTION WITH PROTEINS AT OIL-WATER INTERFACES

Adsorbed film viscoelasticity experiments were conducted in order to study the contribution of diglycerides, monoglycerides and free fatty acids to the interaction between the surface-active fraction of olive oil with bovine serum albumin and sodium caseinate at olive oil-protein solution interfaces. Removal of the surface-active components of natural olive oil by column chromatography, followed by addition of diolein, monoolein or oleic acid to the resulting purified olive oil, brought about a marked decrease in the viscoelasticity parameters of adsorbed bovine serum albumin films. in all the three cases. Furthermore, adsorbed sodium caseinate films remained purely viscous. High viscoelasticity of adsorbed bovine serum albumin and sodium caseinate films at the natural olive oil-protein solution interfaces is attributed to the mixed nature of the films and to the various types of interactions occuring between the adsorbed high and low-molecular weight constituents of the films.