Simple pH treatment as an effective tool to improve the functional properties of ovomucin

Ovomucin has been considered to contribute a lot to the excellent functional properties of egg white. This work focused on investigating the effects of pH and protein concentration on foaming and emulsifying properties of ovomucin to evaluate the proper use of this egg protein as a functional food ingredient, and to clarify its contribution to the functional properties of egg white under different pH conditions. Protein solubility and surface hydrophobicity were measured through the pH ranged from 2.3 to 11.0. Alkali treatment gave ovomucin improved emulsification properties, which were correlated well with the surface hydrophobicity (r ≥ 0.89, P < 0.01). Although ovomucin showed lower foaming capacity in acid and neutral solution, enhanced foaming stability was observed with weak acid-treated ovomucin (pH 5 to 6) compared to native ovomucin. These results demonstrated that acid and alkali treatment, which leads to partial unfolding of ovomucin can improve functional properties of ovomucin, with the greatest improvement for emulsification properties being from the alkali treatment and for foaming stability being from weak acid treatment. These results are helpful to produce unfolding ovomucin suitable for wide range of applications in food industry, and to provide useful information on the proper use of egg white in different food systems.

Ovomucin plays a critical functional role in egg white products. However, it is typically insoluble in distilled water or common salt solutions, which has thus limited its commercial applications. Alkaline treatment resulted in gradual increase in solubility, which markedly enhanced the emulsifying properties, on the other hand foaming stability of ovomucin can be promoted by weak acid treatment. The results of this work help to produce unfolding ovomucin suitable for wide range of applications in food industry, and to provide useful information on the proper use of egg white in different food systems.