Ultrasound-induced structural remodeling of plant proteins for high-internal-phase Pickering emulsion stabilization: A review

High-intensity ultrasound has been used in the preparation of plant-protein-based high-internal-phase Pickering emulsions (HIPPEs) by improving protein dispersion, modifying particle properties, and facilitating droplet breakup and interfacial adsorption. However, its effects depend on when ultrasound is applied during emulsion preparation. Ultrasound may be used as protein pre-sonication before oil addition, applied during emulsification, or introduced after emulsification to reorganize an already formed droplet network. These routes can produce distinct structural and functional outcomes. Ultrasound effects are also influenced by acoustic power, treatment time, protein concentration, oil fraction, sample volume, and temperature control. In this review, ultrasound-assisted HIPPE studies are compared according to these three treatment stages. Additionally, the combined use of ultrasound and other protein modification methods is discussed. Changes in protein structure and droplet characteristics are linked to interfacial adsorption, droplet crowding, and continuous-phase structuring. Protein-to-oil ratio, oil fraction, process scale-up, and validation in food applications are also discussed.