Extraction forms the first basic step in medicinal plant research because the preparation of crude extracts from plants is the starting point for the isolation and purification of chemical constituents present in plants. Extraction techniques have been widely investigated to obtain such valuable natural compounds from plants. The traditional technique requires longer Extraction time and higher solvent consumption. Therefore, there is an increasing demand for new Extraction techniques with shortened Extraction time, reduced organic solvent consumption, and increased pollution prevention. Novel Extraction methods including ultrasound-assisted Extraction, Microwave-assisted Extraction and accelerated solvent Extraction are fast and efficient for extracting chemicals from solid plant matrixes. Extraction method could be extracted maximum nutraceuticals with high pure from solid plant materials if it selected correctly. Also, the yield and quality of nutraceuticals should be considered when an Extraction method is selected.

Determining the best Extraction method to obtain high yield of essential oils from medicinal plants has been identified as one of the challenges in scientific research. The sequential ultrasound-Microwave method is a new Extraction method that in this research has been applied to Extraction of essential oil from basil. In order to investigate the effect of this approach on enhancing Extraction yield, the Microwave method was examined as a base method. To optimize the Extraction conditions of the sequential method, ultrasonic power, Microwave power, and Extraction time were determined as independent variables and essential oil yield as response. Experiments were modeled by central composite design (CCD) of response surface methodology (RSM). The highest yield (2.3% w/w) was obtained at 300 W of ultrasonic power, 600 W of Microwave power, and 40 min of Extraction time. While the base method yield was 0.74% w/w. The chemical composition analysis of the active compounds showed that the number of compounds in the sequential approach is higher than those in the Microwave method. Furthermore, by comparing the antioxidant properties obtained by DPPH and FRAP methods, the sequential method was better in preserving the antioxidant properties of basil essential oil. Scanning electron microscopy images also showed more damage to the glands containing the active ingredients by the sequential process than the base method. Generally, the sequential ultrasound-Microwave method can be introduced as an efficient method for the Extraction of essential oils from Ocimum basilicum.

In this study, Microwave Assisted Solvent Extraction (MASE) was used to recover oil residues from pomace olive using acidic hexane. Results obtained demonstrated that oil Extraction yield increased with time, amount of acetic acid in hexane and power radiation. For both radiation powers used (170 and 510W), the optimal Extraction time and most interesting content of acetic acid in hexane are 1.5 minutes and 5.0% respectively. Oil yield obtained at power 510 W was slightly higher than those corresponding to 170 W. Compared to results obtained with pure hexane, the yield increases were 8.4 % at 170 W and 6.0% at 510 W. However, the oil extracted from pomace olive was found to be of poor quality; indeed only phenolic compounds concentration increased significantly with acetic acid content.