**2.5 Composition of essentials oils**

EOs are generally very complex mixture (60–300) of nonpolar and semipolar lipophilic constituents of low molecular weight, at different concentrations with two or three appearing to be major ones [116, 117]:


The variation in odor and taste of EO depends on the plants variety, the harvesting seasons, the geographical location, the drying methods, and the extraction

techniques [102, 118–120]. The major volatile constituents may be classified into two main categories: terpenoids and polypropanoids [121–123]. We will focus our investigation on terpenoids.
