Essential Oils: An Overview on Origins, Chemistry, Properties and Uses

Plant essential oils are lipid-soluble mixtures of volatile components obtained form the distillation or extraction of flowers, leaves, seeds or other plant organs and collect in concentrated form the typical scent of the plant itself. Although their chemical composition might be quite complex and differ from plant to plant, and even for each botanical species, according to climatic and environmental conditions, usually their components belong to well defined structural types, particularly terpeneoids and phenylpropanoids components, formed as plant secondary metabolites in the mevalonic acid pathway and in the shikimato pathway, respectively. Notable exceptions are the sulphur-containing volatiles from Alliaceae and Brassicaceae families. Essential oils have been used for thousands of years for religious, ornamental (cosmetic), dietary (spices and aromas) or medicinal purposes and possess a wealth of biological properties, among which the antimicrobial is certainly the more general and best documented by modern scientific literature. This chapter introduces their use as natural food additives by providing a brief overview on their history, composition, preparation, analysis, properties and safety for human use.