Physicochemical properties and interfacial dilatational rheological behavior at air-water interface of high intensity ultrasound modified ovalbumin: Effect of ionic strength

Abstract

High intensity ultrasound (HIUS), as an efficient modification method, generally improves the interfacial properties of globular proteins. Herein, to better understand the intrinsic relationship between the foaming property and the interface behavior of HIUS-treated ovalbumin (OVA). The main purpose of this work was to investigate the correlation between the physicochemical properties of high intensity ultrasound (HIUS)-treated ovalbumin (OVA) and interfacial dilatational rheological behavior at air-water interface with different salt ionic strength. The results showed that HIUS treatment resulted in aggregation of OVA dominated by hydrophobic interaction. The size of HIUS-treated OVA gradually increased due to the charge shielding effect caused by the increase of salt ionic strength, while the surface net potential and free sulfhydryl content of the OVA particle were progressively reduced. As a result, the HIUS treated-OVA exhibited the highest diffusion rate and the amount of protein adsorbed at the air-water interface with salt ionic concentrations of 50 mM and 100 mM, respectively. On the other hand, the modified-OVA contact with the air-water interface led to an exposure of aromatic residues, the content of α–helix, β-helix, and β-turn decreased by 6.3%, increased by 10.3%, and decreased by 5.5%, respectively, and there was no salt ion strength dependence. Moreover, the conformational changes resulted in a thiol-disulfide interchange reaction between the OVA molecules at the interface, which was the main contribution to the viscoelastic properties of OVA absorbed layer. These findings provide better insights for an in-depth understanding of the foaming mechanism of ultrasound treated OVA.