Succinylation-driven structural modification of Hippophae rhamnoides L. protein enhances interfacial properties and emulsion performance

Sea buckthorn protein (SBP) is an underutilized plant protein with limited aqueous dispersibility and interfacial functionality. In this study, SBP was modified by succinylation, and the resulting changes in structural, physicochemical, and functional properties were systematically characterized. Succinylation markedly improved the dispersibility of SBP, as evidenced by an increase in solubility from 25.25% to 68.99%, a shift in zeta potential from − 33.82 to − 51.62 mV, and reduced particle aggregation. Structural analysis indicated that succinylation induced moderate conformational rearrangement, including decreased α-helix content, increased random coil content, and changes in the tertiary microenvironment. These changes enhanced the emulsifying performance of SBP, with the emulsifying activity index increasing from 25.02 to 35.71 m²/g. β-carotene-loaded emulsions stabilized by succinylated SBP showed smaller and more uniform droplets, with droplet size decreasing from 2085.47 to 700.53 nm, together with improved encapsulation efficiency and storage stability. During in vitro digestion, free fatty acid release increased from 20.92% to 26.02%, while β-carotene bioaccessibility increased from 10.17% to 27.67%. These results suggest that succinylation improves the functional performance of SBP through a charge-conformation-interface mechanism, thereby enhancing its potential as a plant-based emulsifier for β-carotene-loaded emulsion systems. Graphical