Encapsulation of different spice essential oils in quinoa protein isolate-gum Arabic coacervates for improved stability

A fully plant-based wall material, quinoa protein isolate-gum Arabic (QPI-GA) complex coacervate, was developed for stability improvement of different spice essential oils (EOs): Sichuan pepper EO (SPEO), ginger EO (GEO), and star anise EO (SAEO). The optimum pH and QPI-to-GA ratio to form QPI-GA coacervates were experimentally confirmed to be 3.6 and 4:1. IF, FTIR, and XRD analyses (shown in supplementary information) indicated that complex coacervation generated electrostatic interactions between QPI and GA molecules and caused a more ordered structure of QPI-GA coacervates. The QPI-GA coacervates exhibited high encapsulation efficiency for SPEO (82.53 ± 1.59 %), GEO (88.19 ± 2.37 %), and SAEO (84.68 ± 1.51 %). The encapsulated EOs showed substantially higher stability in comparison to free EOs, while some differences in each type of stability among encapsulated EOs were observed. Additionally, the QPI-GA coacervate wall materials made EOs stable in oral and gastric stages and sustainably release in intestinal stage, which contributed to the excellent absorption of EOs in simulated digestion.