Extraction process optimization of essential oil from Mellissa officinalis L. using a new ultrasound-microwave hybrid-assisted Clevenger hydrodistillation

The limited efficiency of traditional hydrodistillation extraction methods has hindered the development of essential oils (EOs). This study introduces an innovative method for enhancing the production of EOs from Mellissa officinalis L. The method involves ultrasonic and microwave-coupled Clevenger hydrodistillation, which utilizes a proprietary distillation device (PDD) extraction process. Yield optimisation was determined systematically by response surface methodology following single-factor experiments. The maximum extraction yield (0.21 ± 0.0019%) was achieved when the liquid-to-solid ratio, microwave extraction power, and microwave extraction time were set to 9.74 mL/g, 559.60 W, and 75 mins, respectively. The new process produced 74.79% and 73.55% more EOs than the electric furnace heating-assisted PDD and the microwave-assisted traditional Clevenger hydrodistillation. The combination of microwave and a modified PDD showed better results for EOs extraction, and it has great potential to improve the production efficiency of M. officinalis EOs.