Improvement of Physicochemical and Antibacterial Properties of Nanoemulsified Origanum vulgare Essential Oil Through Optimization of Ultrasound Processing Variables.

Water solubility and increased specific surface area are some advantages that essential oil nanoemulsions have over pure oils. Numerous mechanisms to form nanoemulsions are reported in the literature, and even so, there are gaps in the correlations of processing variables and expected specific properties. This study applied a rotating core composite design (CCRD) to describe ultrasound processing variables on the physicochemical and antibacterial properties of Origanum vulgare essential oil nanoemulsion. Droplet size ranged from 41.67 to 231.83 nm with polydispersion between 0.21 and 0.46. All minimum inhibitory concentrations (MIC) observed in nanoemulsions (0.15–1.83 mg/mL) for E. coli and S. aureus were lower than in pure oil (2.36 mg/mL). Droplet size (41 nm), PDI (0.21), zeta potential (−10.13 mV), and MIC (≤ 0.23 mg/mL) properties could be obtained with optimized conditions of 2.9% Tween 80, 157 W, and 4.7 min sonication or 81.4 kJ/mL acoustic energy density. Optimized nanoemulsions stored at 4 °C showed stability over 30 days (< 150 nm), with growth kinetics of 2.54 nm/day. The effects observed in this study may solve some limitations of applying natural antimicrobials. [ABSTRACT FROM AUTHOR]