Impact of hydrodistillation and steam distillation on the yield and chemical composition of essential oils and their comparison with modern isolation techniques

The choice of methods of isolation of essential oils depends mainly on the yield and chemical composition. However, other factors such as cost and use of the essential oil may influence the choice of isolation method. Hydrodistillation and steam distillation are conventional methods used for the isolation of essential oils. These methods are cheap. However, they have limitations such as low yield of the essential oil, loss of volatile components, long isolation time and degradation of some constituents. Recent literature shows that these two methods are the primary methods of choice when it comes to the isolation of essential oils despite their limitations. This paper aims at reviewing these two methods to establish why they are still used, though there are new and improved methods of isolation for volatile oils. It gives an overview on the importance of SD and HD, their effect on the yield and quality of essential oils as well as how these methods compare to the contemporary isolation techniques.