Ultrasonication time dependent structuring of heat-treated legume proteins: interfacial adsorption and stabilization of faba bean and pea protein isolates in high internal phase Pickering emulsions
Hyo Gyeong Lee, Jiseon Lee, Yeon‐Ji Jo, Mi‐Jung Choi
Abstract
This study investigated ultrasonication time dependent restructuring of heat-treated legume proteins, focusing on how sequential heat and ultrasound (HU) treatments influence the interfacial adsorption and stabilization of faba bean protein isolates (FBPIs) and pea protein isolates (PPIs) in high internal phase Pickering emulsions (HIPPEs). Proteins were first modified by heat treatment (90 °C, 2 h) and subsequently subjected to ultrasonication (20 kHz, 120 W, 5-20 min). The resulting samples were characterized in terms of particle size, solubility, turbidity, surface charge, and secondary structure. HU treatment significantly reduced protein aggregation and particle size from 16.44 μm (FCON) to 191.20 nm (FHU20) for FBPI, and from 48.25 μm (PCON) to 279.27 nm (PHU20) for PPI, while solubility increased from 59.29 % to 89.42 % in FBPIs and 38.16 % to 79.85 % in PPIs. Moderate sonication durations (5-10 min) yielded the smallest particles, highest solubility, and most flexible secondary structures, enabling cohesive and elastic interfacial films. By contrast, prolonged sonication (20 min) led to partial reaggregation, weakening interfacial efficiency. HIPPEs stabilized by untreated proteins exhibited larger, heterogeneous droplets, whereas those stabilized by HU-treated proteins exhibited smaller, uniform droplet distributions. Despite the reduced adsorbed protein at interface (AP) and interfacial protein concentration (Γ), CLSM and TEM images confirmed continuous and uniform interfacial layers by the HU-treated proteins, contributing to improved emulsion stability. Rheological analysis further demonstrated the enhanced gel-like structure and viscoelasticity. Overall, the study highlights ultrasonication duration as a critical variable in HU treatment, dictating colloidal restructuring and interfacial adsorption behavior, and underscoring the suitability of legume proteins as clean-label stabilizers for high-oil emulsion systems.