Investigation of Operating Parameters on Ultrasound-Assisted Extraction of Anethole in Fennel Essential Oil

In this paper, the operational impact of three parameters, including the power of ultrasonic apparatus, size of fennel seeds, and experiment time on the extraction yield of anethole, the major component in fennel essential oil and its concentration, have been studied through ultrasound-assisted extraction (UAE). The ultrasonic extraction from fennel seeds using a solution of 70% water-ethanol was studied at different particle sizes, different ultrasonic powers and three different levels of time. The most effective parameter was particle size, while the experiment time had the least impact on both the efficiency and anethole concentration as well. As a result, compared to the Soxhlet method, the ultrasonic-assisted extraction was more efficient. In this experiment, eighteen constituents were identified for fennel seeds using GC–MS. The major components were anethole (78.12%), fenchone (8.81%), limonene (4.39%), and estragole (4.52%). Furthermore, the analysis of two quadratic models using the box-Behnken design (BBD) indicated that the quadratic polynomial model could be applied for estimating the anethole extraction yield as well as anethole concentration.