2.6 Volatile Oils (or Essential Oils)
Volatile oils are the odorous and volatile products of various plant and animal species. As they have a tendency to undergo evaporation on being exposed to the air even at an ambient temperature, they are invariably termed as volatile oils, essential oil or ethereal oils. They mostly contribute to the odorferous constituents or ‘essences’ of the aromatic plants that are used abundantly in enhancing the aroma by seasoning of eatables.
The nature has so meticulously provided specialized secretary structures within the plants which
are primarily responsible for the generation of volatile constitutents, as shown in the following Table 5.2.
Table 5.2 Specialized Secretary Structures Vs Plant Sources
These volatile oils are usually formed by two modes namely; first, by hydrolysis of some glycosides; and secondly, by the protoplasm directly. It has been observed that the volatile oils are present in different parts of a plant as given in Table 5.3.
Table 5.3 Plant Organs Containing Volatile Oils
Volatile oils differ from the fixed oils in many respects which may be enumerated below:
In general, it has been observed that a single volatile oil invariably comprises even more than 200 different chemical components, and mostly the trace constituents are solely responsible for attributing its characteristic flavour and odour.
