The aim of the present work was to study the effect of fatty acids on the properties of protein molecules adsorbed at water/oil interfaces. The systems were studied using dynamic interfacial tension measurements by the pendant drop / axisymmetric drop shape analysis method and Electron Paramagnetic Resonance (EPR) Spectroscopy. The proteins examined were β-lactoglobulin and κ-casein. Biocompatible oils (Miglyol 810, 812, 818 and isopropyl palmitate) were used as the oil phase. The concentrations and conditions in the examined systems were selected within the range found in food systems. The EPR study was performed employing the paramagnetic amphiphilic spin probe 5-doxylstearic acid (5-DSA) and provided information on fatty acid molecular mobility. Oleic acid at increasing concentrations was solubilized in the oil phase. When water was introduced in the system, fatty acid molecules were adsorbed at interface and transferred to the aqueous phase thus affecting the spectral characteristics of the spin probe. The same experimental procedure was followed with the addition of proteins in the aqueous phase. The measurement of dynamic interfacial tension of the same systems provided the adsorption characteristics of each molecule as well as the dynamics of combined adsorption at the interface. The combination of results by both methods provides new insight on the adsorption/transfer/molecular mobility characteristics of the examined systems.
elekalo@food.teithe.gr
