Table 2 Extraction methods [31]
From: Rosmarinus officinalis L. (rosemary) as therapeutic and prophylactic agent
Method | Description |
|---|---|
Maceration | Powdered or crushed materials are left in solvents for at least three days at room temperature under agitation. Them, the solution is filtered. Phytocompounds are released by breaking the cell wall of plant cells. |
Infusion | The same maceration process is used, but the period is shorter, and the sample is boiled in specific volumes of water. |
Decoction | The same maceration and infusion processes are used, but the extractions of thermostable compounds and substances from hard parts of the plant such as roots and bark are possible. |
Percolation | The same maceration and infusion processes are used. The sample is placed in contact with boiling water, and the extraction is performed for about two hours. In the end, a concentrated extract is obtained. |
Soxhlet extraction | The extraction process is performed in the Soxhlet extractor. Sample and solvent are placed in the apparatus. Upon heating the solvent, the solid particles from the substance are extracted. The generated liquid is absorbed and filtered. A more concentrated sample is obtained, and the heating of the solvent does not harm the compound. |
Microwave assisted extraction | Use of microwaves to reach the molecules in a sample inside the solvent. The heating generated on the surface of the sample promotes changes in the structures of the chemical elements and favors the entry of the solvent into the material and consequently the extraction of the compounds. |
Ultrasound-assisted extraction | Ultrasound (20 to 2000 kHz) is used for the extraction of the compounds. In this process, there is an increase in solvent contact with the sample, due to increased permeability of the plant cell wall. Sound waves impair the molecular integrity of the cell wall and thus favor the release of phytochemical agents. |
Accelerated solvent extraction | In an automated way, compounds are extracted from solid and semi-solid samples, using small volumes of solvents, at high temperatures and pressures. |
Supercritical fluid extraction | This extraction is performed using supercritical fluids as solvents, both in solid and liquid samples. Carbon dioxide (CO2) is the most commonly used fluid. This method can also be used for analytical purposes and the removal of unwanted substances or separation of a particular phytocompound in a sample. Temperature and pressure should be considered (~ 31 °C and 74 bar). |