5.1. Extraction of flavour components

From the extraction methods used in industry we will study:

Hydrodistillation
Extraction with organic solvents
Extraction with dense CO₂

The range of components which can be extracted from vegetable matter by the above methods is shown in the following table.

Fractions extracted by different methods (adapted from Richard and Loo, 1989).
Composition			Extraction Method
	Hydrodistillation	Organic Solvents	CO₂ (8 MPa)*	CO₂ (10 MPa)*	CO₂ (30 MPa)*
Essential oils
Esters and heavy terpenes
Fatty acids
Triglycerides
Waxes
Resins
Pigments
* - Extraction temperature = 40º C - Total amount of the extraction; - partial extraction; - no extraction

It is seen from this table that hydrodistillation is the most selective way of extracting essential oils, though extraction with CO₂ at 80 bar pressure is very nearly as good. The other extraction methods shown extract, in addition to the essential oils, substantial amount of the waxy material which is normally present in herbs.