**2. Essential oils**

Essential oils are defined by ISO as '*Product obtained from vegetable raw material either by distillation with water or steam or from the epicarp of Citrus fruits by a mechanical process, or-by dry distillation*' [14]. Buchbauer and his collaborators [15] also define them as *'more or less volatile substances with more or less odorous impact, produced either by steam distillation or dry distillation or by means of a mechanical treatment from one single species'.* Essential oils are famous for their rich composition, mainly aromatic and volatile compounds. Indeed, EOs are composed of 85–99% volatile and 1–15% nonvolatile compounds. Volatile compounds are mainly terpenoids, aldehydes, ketones, esters, methoxy derivatives, acids, alcohols, phenols (eugenol), and methylenedioxy compounds (myristicin). These compounds confer to EOs many biological activities and make them an integral part of everyday life [15, 16]. EOs composition depends on many factors including plant species age, genetic factors, time of harvest, season, and extraction method [11, 17]. EOs are utilized for perfume and cosmetic product formulation. Moreover, they are used in the formulation of deodorizers, air fresheners as well as in the formulation of several pharmaceutical products. In agriculture, EOs are used as biocides. Furthermore, EOs are mainly used in the food industry for their flavors and their antioxidant and antimicrobial properties [18]. Synthetic preservatives are used in the food industry but can induce allergic reactions, intoxications, and even cancer. Therefore, industries are looking for other alternatives such as plant extracts and EOs characterized by their potential antimicrobial and antioxidant activities. Recently**,** there is a growing interest in the use of EOs in food packaging and in food due to their Generally Regarded as Safe (GRAS) and their significant antioxidant and antimicrobial activities [18].
