Classical Methods for Obtaining Essential Oils

An extraction technique is a separation process, used to separate bioactive components from different parts of plant. Mainly, plant extracts are of two types, volatile and non-volatile hydrocarbons. Volatile hydrocarbon that might be saturated or unsaturated, are commonly known as essential oil which bear specific odor. Their extraction from plant sources commonly conducted with classical methods and rarely using modern techniques on large scale. Classical methods own to its simplicity and handling, and cost-effectiveness mostly preferred in all sectors of extracting essential oils (laboratories to industrial scales). These include mechanical treatment, hydro-distillation (water distillation, and steam distillation), cold pressing, solvent extraction, and soxhlet extraction. Choice of the method depends upon the nature of essential oil, solvent used and sensitivity of the process. However, none of the process is ideal; the researcher or industrialist has to compromise one or other parameter such as yield, time, or quality. The aim of this book chapter is to describe different classic methods of extracting essential oil and their efficiency.