Development of Optimized Origanum vulgare L. Essential Oil-Loaded Chitosan/Gum Arabic Nanocapsules by Complex Coacervation

Abstract

Oregano essential oil (OEO), rich in carvacrol and thymol, has bioactive properties but is prone to degradation due to its volatile nature. Nanoencapsulation by complex coacervation, using chitosan (CHI) and gum arabic acid (GA), emerges as an alternative to increase its stability in food matrices. This study investigated the influence of the CHI/GA mass ratio on the formation of OEO-containing nanocapsules and quantified the encapsulated carvacrol using validated GC–MS. A Box–Behnken experimental design optimized the OEO concentration, CHI/GA ratio, and amount of Tween 80. Physicochemical properties such as the diameter, PdI, and zeta potential were evaluated. Morphology was analyzed by SEM and AFM, and thermal stability by TGA and DSC. Stability was monitored for 120 days at 4 °C, 25 °C, and 40 °C. The optimized formulation (470 mg of OEO, 659 mg of CHI/GA 1:5, and 13 mg of Tween) resulted in nanocapsules with a diameter of 323 ± 22 nm, a PdI of 0.20 ± 0.02, and a zeta potential of +15.8 ± 0.8 mV. FTIR analysis confirmed electrostatic interactions between CHI and GA. GC–MS identified 24 constituents in the OEO, with carvacrol as the main compound (78.8%). The validated method showed an R2of 0.9976, proving to be specific, precise, and accurate. The encapsulation efficiency was 95% ± 0.7, indicating that the technique preserved the oil’s composition and concentration. The nanocapsules maintained stability under different temperatures with confirmed structural integrity. It is concluded that nanoencapsulation via complex coacervation, combined with experimental design, allows for the production of stable and effective nanocapsules for the delivery of lipophilic bioactive compounds. The validated analytical method reinforces the system’s applicability in future research and the development of functional products.