A Review on Volatile (Essential) Oils: Chemistry, Extraction Methods, and Industrial Applications

Abstract

Volatile oils, also known as essential oils, are naturally occurring secondary metabolites produced by aromatic and medicinal plants. Although they constitute less than 5% of total plant composition, they possess significant biological and commercial value due to their characteristic aroma and diverse pharmacological activities. These oils are composed mainly of terpenes, terpenoids, and aromatic compounds and are distributed in various plant parts such as flowers, leaves, bark, seeds, fruits, and wood. Volatile oils exhibit distinct physical, chemical, and organoleptic properties, including high volatility, strong odor, optical activity, and solubility in organic solvents. They demonstrate a wide range of biological activities such as antimicrobial, antioxidant, anti-inflammatory, antiviral, and insecticidal effects, making them important in pharmaceutical, cosmetic, food, and aromatherapy industries. Various extraction techniques, including steam distillation, hydrodistillation, expression, solvent extraction, enfleurage, and supercritical CO₂ extraction, are employed based on the nature of plant material and desired oil quality. Each method influences the yield, purity, and stability of the extracted oil.