Optimization and Physicochemical Characterization of a Self-nanoemulsifying Drug Delivery System (SNEDDS) for Citronella Essential Oil (Cymbopogon nardus)

Indonesia produces abundant citronella essential oil, which contains diverse bioactive compounds with promising potential as natural feed additives, yet scientific evidence supporting its application in poultry nutrition remains limited. This study aimed to select the optimal and safest material composition for a self-nanoemulsifying drug delivery system (SNEDDS) of citronella essential oil using Design Expert Ver. 13.0.1.0, a D-optimal mixture, and to characterize the resulting formulation as a prospective poultry feed additive. Component selection, composition ratios, and oil phase proportions were determined using an exploratory approach: homogenization at 250 rpm for 15 minutes, followed by ultrasonication. The prepared SNEDDS formulations were evaluated through comprehensive physicochemical characterization, including organoleptic properties, percentage transmittance, emulsification time, dynamic light scattering (DLS) analysis, stability testing, and morphological observation. The composition ingredients of citronella SNEDDS consisted of virgin coconut oil (VCO) as the carrier oil, Tween 80 as the surfactant, and PEG 400 as the cosurfactant. The optimum formula consisted of 17.86% oil phase (citronella essential oil and VCO with a ratio of 50:50 [%]), 62.791% surfactant, and 19.169% cosurfactant. It demonstrated high transmittance (99.338% ± 0.366%), rapid emulsification (32.107 ± 0.454 s), small particle size (14.4 ± 0.141 nm), low polydispersity index (PDI) (0.088 ± 0.025), moderate zeta potential (–17.00 ± 2.980 mV), and appropriate viscosity (376.00 ± 3.637 mPa•s).