Structure and Dynamics of Veiled Virgin Olive Oil: Influence of Production Conditions and Relation to its Antioxidant Capacity

Abstract

Structure and dynamics of the colloidal dispersions in veiled virgin olive oil (VVOO), the fresh olive juice, were for the first time investigated with different scattering techniques and related to the extraction conditions applied by the olive oil producers. VVOO samples were produced with either the three-phase extraction procedure (oil/externally added water) at different malaxation times, or by the dual-phase extraction procedure (no externally added water). Static light scattering (Small angle light scattering apparatus SALSA), dynamic light scattering, based on a 3D cross-correlation system, a flat cell and a red HeNe-Laser with 632,8 nm wavelength (3D-DLS), classical dynamic light scattering using a goniometer with cylindrical cells and a green laser with 532 nm wavelength, (Green-DLS), and small angle X-ray scattering (SAXS), are the scattering techniques that were used for the analysis of the samples. In addition, samples of VVOO were analyzed with a confocal microscope. SAXS technique gave almost the same results for all the samples of VVOO indicating comparable nano-structure due to the triglyceride backbone. When 3D-DLS and Green DLS were applied to the VVOO samples, quite different results were obtained. In addition, from the microscopic study of the VVOO samples discrete droplets but no anisotropic crystals could be observed. Finally, radical scavenging activity measurements applying Electron Paramagnetic Resonance spectroscopy showed that the antioxidant capacity of the veiled VVO was higher than the one of the filtered oils. Between the two oil extraction systems the dual phase one seems to be more appropriate for the production of stable and rich in minor constituents olive oils.