Fabrication and Characterisation of Lime Essential Oil Nanoemulsion Using the Emulsion Inversion Point ( <scp>EIP</scp> ) Method

ABSTRACT Lime essential oil (EO), which possesses a fresh and cheerful aroma, strong antioxidants and antibacterial activities, is widely used in the food, cosmetic and pharmaceutical industries. However, it is insoluble in water and sensitive to environmental factors. Therefore, the objective of this study was to fabricate a lime essential oil nanoemulsion using the emulsion inversion point (EIP) method and to evaluate its particle characteristics, antioxidant capacity and stability under various storage conditions. The EO, extracted from Citrus limonia Osbeck peel, comprised 57 volatile compounds, of which 29 compounds had concentrations exceeding 0.05%. The nanoemulsion was prepared using lime EO and coconut oil (6:4) at a 10% oil‐phase concentration, with a 1:1 surfactant‐to‐oil ratio and a Tween 80:lecithin ratio of 8:2 under 1200 rpm mixing. The resulting formulation exhibited a mean particle size of 76.79 ± 1.25 nm, a PDI of 0.316 ± 0.003, and a zeta potential of −50.8 ± 1.75 mV. The antioxidant activity of lime EO was preserved after nanoemulsion encapsulation, with IC 50 values of 33.5 and 29.0 mg/mL for DPPH and ABTS assays, respectively. During a 28‐day storage period, particle sizes of the nanoemulsion slightly increased, whereas its PDIs decreased, and its zeta potential remained unchanged. Over 28 days, the encapsulation efficiency of the lime essential oil nanoemulsion ranged from 77.79% to 78.31%, with a total of 47 volatile compounds retained. As a result, the lime essential oil nanoemulsion, which preserves key volatile compounds and maintains antioxidant capacity, is a promising material for developing food, cosmetic and pharmaceutical products.