Impact of evironment conditions on physicochemical characteristics of ovalbumin heat-induced nanoparticles and on their ability to bind PUFAs

Abstract

In this work, OVA heat-induced aggregates were obtained by controlled heat treatment varying temperature (60, 70 and 80ºC), heating time (3, 5 and10 min), aqueous medium pH (5.5, 6.0 and 6.5) and protein concentration (5, 10 and 14.2 g/L). Particle size distribution and surface characteristics derived from fluorescence spectroscopy (both intrinsic and extrinsic) were determined. Evaluation of these physicochemical properties allowed knowing experimental conditions under which nanometric OVA aggregates (OVAn), with suitable surface hydrophobicity, could be produced. OVAn ability to bind polyunsaturated fatty acid (PUFA) was carried out by turbidity measurement. In these experiments, linoleic acid (LA) was used as a PUFA model. In general, OVA aggregate sizes increased with temperature, time and protein concentration, furthermore at higher pH value, OVA aggregate sizes were lower. OVA aggregates surface hydrophobicity increased with rising heating temperature and the pH value indicating, on one hand, larger protein unfolding and on the other hand lower aggregation via hydrophobic interaction at higher pH value, respectively. However, surface hydrophobicity decreased with concentration suggesting greater aggregation. OVAn obtained at 70°C, 10 g/L, pH 6-6.5 and 70°C, 5 g/L, pH 6 were assayed by LA binding ability. This property was 1.4-2.0 folds greater than for native OVA. Information derived from this work could be of practical interest for the development of innovative PUFAs carrier systems.