*2.3.1.1.3 Solvent extraction*

Also known as liquid–liquid partitioning, its principle is based on the solubility in an organic solvent non-mixable to water. This technique is used on delicate plants to produce higher amounts of EOs at a lower cost. The method is limited by the compound solubility in the specific solvent used, long extraction time, relatively high solvent consumption and often unsatisfactory reproducibility and purity (**Figure 3**) [33].

*Diagrammatic illustration of steam distillation method [32].*

**79**

**Figure 4.**

*Soxhlet equipment [35].*

*Terpenoids as Important Bioactive Constituents of Essential Oils DOI: http://dx.doi.org/10.5772/10.5772/intechopen.91426*

to increase the extraction kinetic of the system.

the sample is diluted in a large volume of solvent.

Typically, it is a solid–liquid extraction used when the desired compound has a limited solubility in a solvent and the impurity is insoluble in that solvent. There are

several advantages of using this technique. These advantages include:

• Low solvent consumption for a larger amount of raw material,

• Repeatedly brought into contact with fresh portions of the solvent, this prevents the possibility of the solvent to become saturated with extractable material and enhances the removal of analyte from the matrix. Moreover, the temperature of the system is close to the boiling point of the solvent. This helps

As disadvantages, it requires several hours or days to be performed; moreover,

Due to heating, the thermal degradation and volatilization of components have been observed, and hydrolysis of esters to yield alcohols and carboxylic acids can

Also kwon as scarification method, this is one of the best methods to extract EOs. The term cool pressed theoretically means that the oil is expeller-pressed at low temperature and pressure. This process insures that the resulting oil is 100% pure and retains all the properties of the plant. Here the heat is reduced and minimized throughout the batching of the raw material. EOs are then separated from the

Since economy, competitiveness, eco-friendly, sustainability, operation costs, high efficiency, and good quality become keywords of the modern industrial production, the development of EO extraction techniques has never been interrupted. The most relevant disadvantage of conventional techniques are time and solvent consumption and also related to the thermolability of EOs components which undergo chemical alteration (hydrolyze, isomerization, oxidation) due to the high

*2.3.1.1.4 Soxhlet extraction*

occur (**Figure 4**) [34].

*2.3.1.1.5 Cool pressing method*

material by centrifugation [36].

**Figure 3.** *Illustration of liquid–liquid extraction method.*
