Ultrasound-assisted tannic acid crosslinking of myofibrillar protein-stabilized high internal phase emulsions: Enhanced stability, mechanical properties, and 3D printability

The study investigated the synergistic effects of high ultrasound (HS) treatment and tannic acid (TA) conjugation on the structural and interfacial properties of myofibrillar protein (MP), and their roles in stabilizing high internal phase emulsions (HIPEs). Spectroscopic and interfacial analyses showed that HS promoted TA-induced covalent conjugation via exposure of reactive groups, driving conformational rearrangements and formation of more compact aggregates. At moderate TA concentrations, smaller particle size and enhanced interfacial performance were observed for MP-TA conjugates, as evidenced by accelerated adsorption kinetics and elevated dilatational moduli of interfacial films. In HIPEs, these changes yielded smaller and more uniform droplets, higher viscosity, larger linear viscoelastic regions, and greater yield stress. These improvements resulted in greater resistance to coalescence and oiling-off under storage, heating, and centrifugal stress. MP-based HIPEs with 10μM g^-1 TA and 240 W HS exhibited the most favorable balance of droplet architecture, rheology and stability. In addition, the optimized HIPEs displayed good printability in a preliminary 3D printing test, highlighting their potential for structuring food matrices. Overall, this work elucidates how HS-assisted TA conjugation alters MP conformation, interfacial assembly and emulsion rheology, providing a mechanistic basis for designing robust MP-stabilized HIPEs.