*Article* **Preparation, Characterization, and Antioxidant Activity of Nanoemulsions Incorporating Lemon Essential Oil**

**Ting Liu 1,2, Zhipeng Gao 3, Weiming Zhong 3, Fuhua Fu 1,2, Gaoyang Li 1,2, Jiajing Guo 1,2,\* and Yang Shan 1,2,\***


**Abstract:** Lemon essential oil (LEO) is a kind of citrus essential oil with antioxidant, anti-inflammatory, and antimicrobial activities, but low water solubility and biological instability hinder its industrial application. In this study, LEO was nanoemulsified to solve these problems. The preparation procedure of lemon essential oil nanoemulsions (LEO-NEs) was optimized, and the physicochemical characterization and antioxidant activities were explored. Single-factor experiments (SFEs) and response surface methodology (RSM) were conducted for the effects on the mean droplet size of LEO-NEs. Five factors of SFE which may influence the droplet size were identified: HLB value, concentration of essential oil, concentration of surfactant, ultrasonic power, and ultrasonic time. On the basis of the SFE, the RSM approach was used to optimize the preparation procedure to obtain LEO-NEs with the smallest droplet size. LEO-NEs exhibited good antioxidant activity when the HLB value was 13, content of surfactant was 0.157 g/mL, ultrasonic time was 23.50 min, and ultrasonic power was 761.65 W. In conclusion, these results can provide a good theoretical basis for the industrial application of lemon essential oil.

**Keywords:** lemon essential oil; nanoemulsions; ultrasonication; response surface methodology; antioxidant activities
