A Comparison of Sonication and Phase Inversion Temperature Methods for Formulating Lavender Essential Oil Nanoemulsions: Stability, Antioxidant Capacity, and Industrial Potential

Abstract

Lavender essential oil (LEO) nanoemulsions are gaining attention for their enhanced stability and antioxidant properties, making them suitable for applications in pharmaceuticals, cosmetics, and the food industry. Despite the widespread use of the high-energy sonication method, the phase inversion temperature (PIT) method has been underexplored in the preparation of LEO-based nanoemulsions. This study aims to address this gap by comparing the efficacy of the low-energy PIT method with the high-energy sonication method in terms of stability and antioxidant capacity. The objectives were to evaluate the physical characteristics (particle size, polydispersity index (PDI), zeta potential, and turbidity) and the antioxidant capacity of nanoemulsions prepared by both methods. The results showed that PIT-prepared nanoemulsions, with slightly larger but more uniform droplet sizes (47.53 ± 0.306 nm, PDI: 0.408 ± 0.005), exhibited superior zeta potential (–14.60 ± 0.436 mV) and enhanced stability compared to those prepared by sonication (47.23 ± 0.252 nm, PDI: 0.466 ± 0.004). Furthermore, PIT-prepared nanoemulsions retained higher antioxidant capacity over a 30-day period. The techno-economic analysis revealed that while sonication is more energy-intensive, the PIT method offers better scalability and lower production costs. These findings suggest that the PIT method holds significant potential for large-scale industrial applications, offering a more cost-effective and sustainable approach for enhancing the stability and antioxidant capacity of LEO nanoemulsions.