Linoleic acid binding properties of ovalbumin nanoparticles

In the present work, ovalbumin (OVA) solutions (10 g/L, 50 mM NaCl, pH 7.5) were heat-treated at 75, 80 and 85 degrees C (namely, OVA-75, OVA-80 and OVA-85, respectively), from 0 to 25 min. OVA nanopartides (OVA(n)) around 100nm were obtained. For 3 min of heat treatment, OVA(n) sizes increased with temperature, but for a heating time longer than 10min, OVA-75 showed the highest size values. OVA(n) surface hydrophobicity increased 6-8 folds in comparison with native OVA and wavelength blue shifts of 25-30 nm in maximum fluorescence intensity were registered. These results suggest that buried hydrophobic residues were exposed to the aqueous medium. Binding experiments with linoleic acid (LA) as polyunsaturated fatty acid (PUFA) model were carried out. Firstly, binding ability of OVA(n) was determined from LA titration curves of intrinsic fluorescence measurements. OVA-85 at 5 min presented the highest binding ability and it was used for further binding properties studies (turbidity, particle size distribution - PSD - analysis and zeta-potential measurements). Turbidity measurement and PSD analysis showed that OVA(n)-LA nanocomplexes were formed, avoiding LA supramolecular self-assembly formation. The union of LA to OVA(n) surface confers them significant lower zeta-potential and larger size. Hence, fluorescence and zeta-potential results showed that LA would bind to OVA(n) by mean Of hydrophobic interactions. Information derived from this work could be important to potentially use OVA(n) as PUFA vehiculization with applications in several industrial sectors (food, pharmaceutical, cosmetics, etc.). (c) 2015 Elsevier B.V. All rights reserved.