Effect of simultaneous ultrasonic and microwave assisted hydrodistillation on the yield, composition, antibacterial and antibiofilm activity of essential oils from Citrus medica L. var. sarcodactylis

Simultaneous ultrasonic/microwave assisted hydrodistillation extraction (UMHE) was first employed to extract essential oil. Meanwhile, the effects of UMHE, hydrodistillation extraction (HE), microwave assisted hydrodistillation extraction (MHE) and solvent extraction (SE) on the yield, chemical composition, antibacterial and antibiofilm activity of essential oil were evaluated. The optimized conditions determined by response surface methodology were as follows: solvent to solid ratio was 5.2:1 (ml/g), extraction time was 15.5 min, and microwave power was 816 W. Moreover, 15 min was sufficient for UMHE to obtain higher yield than that by HE for 1.5 h, indicating a significant reduction of extraction time and an improvement of efficiency. Forty five compounds were identified in the essential oil through GC-MS analysis. The composition of essential oils obtained by UMHE, MHE and HE was similar, and the major compounds were D-Limonene, γ-Terpinene and α-Pinene. Moreover, the results indicated that the antibacterial activity of the essential oils was similar. All the essential oils exhibited inhibitive effect on biofilm formation. The inhibitive effect of essential oils of HE and UMHE was significantly higher than that of the essential oil obtained by SE. This study suggests that UMHE is a rapid and efficient alternative for the extraction of essential oils, with a nice potential for application. Also, UMHE provides a possible approach to improve the antibacterial and antibiofilm activity of essential oils.