Effect of benzoic acid-based and cinnamic acid-based polyphenols on foaming properties of ovalbumin at acidic, neutral and alkaline pH conditions

Abstract

To broaden the application of ovalbumin (OVA) in food formulations, it is meaningful to improve its foaming characteristics. This study aimed to investigate the effect of benzoic acid-based (3,4-dihydroxybenzoic acid, DA) and cinnamic acid-based polyphenols ( trans -2-hydroxycinnamic acid, T2A) on the foaming properties of OVA at acidic (pH 3.0), neutral (pH 7.4) and alkaline (pH 9.0) pH conditions. Both the addition of polyphenols and acid treatment enhanced the foaming properties of OVA. Surface hydrophobicity , circular dichroism , free sulfhydryl groups , and Fourier transform infrared spectroscopy results indicated that after acidic workup, the presence of stronger hydrophobic interactions in OVA-polyphenol aggregates induced more disordered protein conformation and conversion or breakage of disulfide bonds . Particle size and zeta potential indicated that acidic treatment neutralized protein surface charges, further inducing self-aggregation and swelling of OVA, ultimately enhancing foaming properties. Comparatively, T2A exhibited better foam-inducing capacity due to its stronger interaction with OVA, leading to the unfolding of the OVA structure and the exposure of more hydrophobic groups. The intrinsic and 3-D fluorescence spectra experiments also confirmed that OVA-T2A aggregates at pH 3.0 had greater altered non-covalent interaction forces and protein secondary and tertiary structures compared to other complexes. This study provides a theoretical basis for designing protein formulations with excellent foaming properties. • The combined treatment of pH and polyphenols (PP) improved foaming of ovalbumin (OVA). • OVA structure unfolding was associated with excellent foaming properties. • Weak electrostatic repulsion and enhanced intermolecular force at pH 3.0 promoted OVA aggregation and conformational changes. • pH 9.0 induced strong electrostatic repulsion between aggregates, negatively affecting protein unfolding. • Cinnamic acid-based PP had higher affinity with OVA, thus facilitating greater structural unfolding and foaming of OVA.