Zein–Lecithin Complex Nanoparticles as Bio-Nanocarriers for Encapsulation and Sustained Release of Eucalyptus Oil

The growing demand for natural, biocompatible, and consumer-friendly ingredient-based delivery systems for encapsulation of bioactives has driven significant advancement in developing innovative formulations to enhance the stability, bioavailability, and slow & sustained release. This study focuses on fabricating zein/lecithin nanoparticles (ZLNPs) for the encapsulation and controlled release of eucalyptus oil (EuO), a hydrophobic essential oil (EO) with potential applications in food preservation. Zein and lecithin are food-grade and GRAS (Generally Recognized as Safe) certified. Different mass ratios of zein to lecithin were utilized to determine the optimal ratio for stable complex formation, with hydrophobic and electrostatic interactions playing key roles in the stability of ZLNPs. EuO was successfully encapsulated in the hydrophobic core of zein, which was surrounded by lecithin molecules. NPs with zein-to-lecithin mass ratios of 1:1 and 1:2 exhibited the smallest sizes, with 72.48 and 38.34 nm radii and ζ-potentials of −22.1 and −23.2 mV, respectively. The ZLNPs exhibited excellent stability under varying pH conditions (pH 2–8), salt concentrations (0–400 mM NaCl), and storage over 30 days. Furthermore, ZLNPs demonstrated a controlled and sustained release of EuO from the zein/lecithin complex matrix. These findings highlight the potential of ZLNP-based bionanocarrier systems for encapsulating and delivering bioactive compounds. The sustained release and enhanced stability of EuO suggest that this system is a promising candidate for food preservation applications.