Weakly basic electrolysed water combined with ultrasound for enhancing the binding and functional properties of Antarctic krill protein-gallic acid complexes.

Ultrasonic treatment is an effective strategy for modifying protein structure. However, the accompanying generation of reactive oxygen species (ROS) inevitably induces protein oxidation and polyphenol degradation, compromising the functional performance of protein-polyphenol complexes. This study combined weakly basic electrolysed water (WBEW) with ultrasonic treatment to investigate its protective effects on the complexation between Antarctic krill protein and gallic acid (GA), as well as the structural and functional properties of the resulting complexes. WBEW effectively quenched ultrasound-generated •OH, reducing •OH levels from 4.36 to 3.02 μmol/L after 40 min of ultrasonication. Consequently, WBEW significantly suppressed protein carbonylation and sulphydryl loss and notably enhanced GA retention. A maximum binding efficiency of 34.8% was achieved at 20 min of ultrasonication in WBEW, corresponding to optimal particle size reduction (202.3 nm), improved solubility, and superior surface hydrophobicity. Fourier-transform infrared and fluorescence spectroscopy revealed that WBEW alleviated ultrasound-induced secondary and tertiary structural perturbations, maintaining more ordered conformations. The WBEW-20 complex exhibited significantly increased emulsifying activity (40.3 m2/g) and emulsifying stability indices, enabling the formation of high-internal-phase emulsions with uniform droplet size and thick interfacial layers. Moreover, emulsions stabilised by the WBEW-20 complex demonstrated remarkably lower peroxide (20.1 mmol/kg) and malondialdehyde (4.34 mmol/kg) values after 11 days of storage than the controls, along with superior thermal and ultraviolet oxidation resistance. These findings establish WBEW-assisted ultrasound treatment as a promising modification strategy for upgrading marine protein-polyphenol complexes with enhanced emulsifying and antioxidant functionalities for application in oxidation-sensitive food systems.