2.2.6. Characterization of nanoemulsion

Particle size, polydispersity index (PDI), and zeta potential of nanoemulsions were evaluated by dynamic light scattering technology using Zetasizer (S90) instrument at 25°C. The nanoemulsion was diluted 20‐fold in deionized water to escape multiple scattering effects (Razavi et al., ²⁰²⁰). The encapsulation efficiency (EE) of BSE was calculated by measuring the amount of total phenolic compounds (TPC) of the extract before and after encapsulation. The ratio of unencapsulated TPC on TPC before encapsulation has been considered as EE (Rahnemoon et al., ²⁰²¹). Nanoemulsions were dried using a freeze dryer (VaCO5, Zirbus) at 0.017 mPa and −57°C for 48 h. Then, the morphology of nanoemulsions was examined using a scanning electron microscope (Mira 3 LMU, Tescan, Czech Republic). For this purpose, samples were attached to aluminum stubs and covered with a thin layer of gold. The voltage device was 15 kV, and images were taken at 1000× magnification (Razavi et al., ²⁰²⁰).