Green Fabrication of Lactoferrin–Dendrobium Polysaccharide–EGCG Ternary Nanoparticles for Enhanced Lutein Delivery

Lutein’s application in functional foods is limited by its poor solubility, instability, and low bioavailability. To address these challenges, ternary nanoparticles (LF-DOP-EGCG) were constructed using lactoferrin (LF), Dendrobium officinale polysaccharide (DOP), and epigallocatechin gallate (EGCG) via a surfactant-free, organic-solvent-free aqueous process. Optimized preparation conditions (0.5% LF, pH 3, LF/DOP-EGCG mass ratio 3:1) produced uniformly sized and well-dispersed nanoparticles. Spectroscopic analyses confirmed that DOP-EGCG interactions altered the secondary structure of LF. Compared with non-covalent complexes, covalently modified nanoparticles (LF-COV) exhibited improved thermal stability and antioxidant capacity. Lutein-loaded nanoparticles showed efficient encapsulation and loading, and spectral shifts verified successful incorporation. Covalently modified lutein-loaded nanoparticles (LF-COV-LUT) demonstrated markedly enhanced stability under heat, light exposure, and 40-day storage relative to free lutein. In vitro digestion further revealed that LF-COV-LUT slowed gastric degradation and facilitated intestinal release, resulting in significantly higher bioaccessibility (54.6 ± 8.7%) compared with free lutein (6.13 ± 0.83%). These findings indicate that this natural multicomponent nanoparticle system provides a green and effective approach for improving the stability and digestive availability of carotenoids in functional food applications.