Structural and interfacial characteristics of ultrasonicated lipophilic-protein-stabilized high internal phase Pickering emulsions

Soybean lipophilic protein (LP) can stabilize high internal phase Pickering emulsions (HIPPE) under acidic conditions (pH 2.0); thus, it is vital for the targeted release of functional nutrients. However, the high fat content and low solubility of LP under acidic conditions hinder the functional properties of HIPPEs. We explored the effect of ultrasonic compound acid treatment on the structure and functional properties of LP. The effects of varying ultrasonication power (0, 150, 250, 350, and 450 W) for 10 min on the freeze–thaw stability and interfacial characteristics of the modified LP-stabilized HIPPE were evaluated using particle size, rheological, and differential scanning calorimetry. The results showed that LP sonicated at 350 W exhibited a small particle size (minimum 250 nm), high absolute zeta potential (maximum 28 mV), and the maximum solubility. Following ultrasonication, LP covered the oil–water interface more uniformly, and the adsorbed protein percentage increased significantly (p < 0.05) to 53%. LP-stabilized HIPPE possessed a stronger gel-like network and exhibited significantly increased freeze–thaw stability (p < 0.05). Our results indicate that ultrasonication can change the structural and functional properties of LP, providing a theoretical reference for further applications of acid emulsions in the food industry.