Encapsulation of Lutein Within Ultrasonicated Peach Gum-Sodium Caseinate Complex Nanoparticles Via Electrostatic Complexation: Physiochemical Properties, Structural Interaction Mechanisms, and In Vitro Release Analyses

This study involved the fabrication of sonicated complex nanoparticles designed to encapsulate and deliver lutein (LU) via the electrostatic complexation of peach gum (PG) and sodium caseinate (SC), thereby improving its physicochemical stability and bioaccessibility. The sonicated LU-loaded PG-SC complex nanoparticles (LU-PS/CNPs) were studied in terms of their physicochemical properties (mean droplet size (MDS), polydispersity index (PDI), zeta potential (ZP), encapsulation efficiency (EE), loading capacity (LC), and physical stability), structural analysis, and morphological observation. The study found that 2.0% LU in the F4 formulation (LU-PS/CNPs) had the highest EE of 85.07% and LC of 20.05%, compared to 2.5% LU in the F5 formulation (LU-PS/CNPs) with 84.96% EE and 19.89% LC, respectively. We investigated the formation mechanism of sonicated LU-PS/CNPs through FT-IR and molecular docking, which encompassed hydrophobic interactions, electrostatic attractions, and hydrogen bonding. FT-IR and XRD analyses confirmed the successful encapsulation of LU by the sonicated LU-PS/CNPs. Furthermore, the changes in crystalline structure and thermal stability of LU within sonicated LU-PS/CNPs were examined through XRD and TGA analysis, respectively. Moreover, the F4 formulation retained more LU than the non-encapsulated LU and the F5 formulation at -20, 4, 25, and 45 °C. Additionally, the F4 formulation showed a stronger antioxidant effect along with a better, more gradual, and longer release of encapsulated LU during in vitro digestion than the F5 formulation. The CLSM images further validated the structural changes before and after the in vitro digestion of LU-PS/CNPs. The thorough examination of the encapsulation and delivery of LU within complex nanoparticles yields significant insights into the advancement of functional foods.