Ultrasonic-boosted succinylation of walnut protein isolate: Unlocking enhanced functionalities and structural insights

This study aims to improve the functional properties of walnut protein isolate (WPI), particularly its solubility and interfacial activity, through ultrasound-assisted succinylation. WPI was treated with succinic anhydride at concentrations of 5 %, 10 %, and 15 % (<i>w</i>/w), with or without ultrasound assistance (300 W, 20 min). The effects on WPI's structure and functionality were systematically evaluated. Succinylation improved protein functionality, and ultrasound further enhanced this by promoting unfolding and increasing modification efficiency. FTIR, fluorescence spectroscopy, and SDS-PAGE analyses revealed notable changes in secondary and tertiary structures. Microscopic observations showed that succinylation transformed WPI into a more dispersed flake-like structure. These structural changes contributed to a 2.85-fold improvement in solubility. Molecular dynamics simulations revealed the mechanism by which ultrasound promotes the succinylation reaction. Pearson correlation confirmed strong links between succinylation degree, solubility, and functional performance. This study provides an effective way to improve plant protein function.