In the current research, the effects of different ohmic assisted hydrodistillation (OAHD) parameters including voltages gradient (5, 15 and 25 v/cm), extraction time (30, 75 and 120 min) and NaCl concentrations (0.5, 1 and 1.5%) on the extraction yield, energy consumption and total phenol content (TPC) of Salix aegyptiaca L.essential oil were investigated, and then compared with conventional hydrodistillation (HD). Finally, artificial neural network (ANN) modeling is utilized to predict kinetics of essential oil extraction. Result revealed that extraction time and voltage gradient had significant effect on extraction yield, energy consumption and TPC (p<0.05). Extraction yields of essential oil obtained by OAHD and HD were 0.119 ± 0.012 and 0.081 ± 0.01, respectively. There was no significant difference (p>0.05) between specific gravity, refractive index and TPC of essential oil of OAHD and HD methods, however IC₅₀ of essential oil extracted by OAHD was significantly higher than essential oil obtained with HD method (p<0.05). To design the ANN model, voltages gradient, extraction time and salt concentrations and their interactions were considered as input vectors while the extraction yield of essential oil was considered as the model output. The results showed that the best prediction performance belonged to 3-9-8-1 ANN architecture (RMSE=0.036 and R²=0.99). Therefore, it can be concluded that the OAHD method is applicable for S. aegyptiaca L. essential oil extraction and ANN model is an efficient quantitative tool to predict the kinetics of essential oil extraction.

The aim of the present research was modeling and optimizing the ultrasound-assisted hydrodistillation (USHD) of essential oil extraction process and comparing the effects of hydrodistillation (HD) and USHD techniques on the musk willow (Salix aegyptiaca L.) essential oil. Sonication time (15-45 min), ultrasound power level (100-500 W) and water to plant ratio (3-10 (v/w)) were varied in order to maximize S. aegyptiaca L.essential oil yield, total phenolic content (TPC) and IC₅₀. The effect of sonication time and sound power levels on the essential oil yield, TPC and IC₅₀ was significant at the 5% level. Although increasing water to plant ratio parameter significantly resulted in a higher yield (p<0.05), however, this parameter no significant effect the TPC and IC₅₀ (p>0.05). The optimum parameters were sonication time of 39 min, sound power levels of 189 w, and water to plant ratio of 6.8 V/W. Under optimum conditions, both USHD and HD methods were used for essential oil extraction. USHD showed a significantly higher amount of extraction yield (0.108±0.009% (v/w)) compared to the HD (0.081±0.01% (v/w)) (p<0.05). Compared to the HD extraction, the USHD resulted in a shorter extraction time, less energy consumption, higher antioxidant properties and a higher extraction yield. Physical properties of OAHD and HD essential oils were not significantly different (p>0.05). Among the four kinetics models, the sigmoid model was shown to be the best one. This model can be used for modeling the kinetics of essential oil extraction by both HD and USHD.