Consequences of phosphorylation on the structural and foaming properties of ovalbumin under wet-heating conditions.

Abstract In this study, ovalbumin (OVA) was phosphorylated under wet-heating in the presence of sodium tripolyphosphate at pH 6.0 and 60 °C for 1, 2, 3, 4 and 5 h, and the structural and physical properties of phosphorylated OVA (P-OVA) were investigated. The FT-IR spectrum confirmed the covalent attachment of the phosphate group to OVA. New possible phosphate sites (Ser-221, Ser-269, Tyr-281 and Ser-324) were detected by using liquid chromatography in tandem with mass spectrometry. Circular dichroism (CD) spectra demonstrated that P-OVA molecular became more flexible and disordered. The decreased fluorescence intensity indicated that the chromophore microenvironment became more exposed and polar because of conformational changes. The surface hydrophobicity (H 0) and the absolute value of zeta potential of P-OVA obtained at 5 h was 1.8 and 1.5 times higher than that of N-OVA. Foaming ability (FA) and foaming stability (FS) were enhanced by 1.7 and 4.4 times after wet-heating phosphorylation for 4 h, which were up to 87.0% and 28.5%, respectively. Furthermore, the correlation analysis suggested that FA was significantly correlated to random structure (P < 0.01) and H 0 (P < 0.01), and zeta potential was related with FS (P < 0.05). Graphical abstract Image 102 Highlights • Ovalbumin was phosphorylated by sodium tripolyphosphate under wet-heating. • Possible phosphate sites were detected by LC-MS/MS. • Structural changes were confirmed by fluorescence and CD spectrum. • H 0 and the absolute value of zeta potential increased after the phosphorylation. • Foaming ability and stability were promoted by phosphorylation. [ABSTRACT FROM AUTHOR]